2010

SERVICE MANUAL

YP125R/YP250R

37P-F8197-E0
EAS20060

YP125R/YP250R 2010
SERVICE MANUAL
©2009 by Yamaha Motor España, S.A.
First edition, November 2009
All rights reserved.
Any reproduction or unauthorized use
without the written permission of
Yamaha Motor España, S.A.
is expressly prohibited.
EAS20071

IMPORTANT
This manual was produced by Yamaha Motor España, S.A. primarily for use by Yamaha and MBK deal-
ers and their qualified mechanics. It is not possible to include all the knowledge of a mechanic in one
manual. Therefore, anyone who uses this book to perform maintenance and repairs on Yamaha and
MBK vehicles should have a basic understanding of mechanics and the techniques to repair these
types of vehicles. Repair and maintenance work attempted by anyone without this knowledge is likely
to render the vehicle unsafe and unfit for use.
Yamaha Motor España, S.A. is continually striving to improve all of its models. Modifications and sig-
nificant changes in specifications or procedures will be forwarded to all authorized Yamaha and MBK
dealers and will appear in future editions of this manual where applicable.
TIP
Designs and specifications are subject to change without notice.

EAS20081

IMPORTANT MANUAL INFORMATION

Particularly important information is distinguished in this manual by the following notations.
This is the safety alert symbol. It is used to alert you to potential person-
al injury hazards. Obey all safety messages that follow this symbol to
avoid possible injury or death.

A WARNING indicates a hazardous situation which, if not avoided, could

WARNING result in death or serious injury.

A NOTICE indicates special precautions that must be taken to avoid

NOTICE damage to the vehicle or other property.

TIP A TIP provides key information to make procedures easier or clearer.

EAS20090

HOW TO USE THIS MANUAL

This manual is intended as a handy, easy-to-read reference book for the mechanic. Comprehensive
explanations of all installation, removal, disassembly, assembly, repair and check procedures are laid
out with the individual steps in sequential order.
• The manual is divided into chapters and each chapter is divided into sections. The current section title
“1” is shown at the top of each page.
• Sub-section titles “2” appear in smaller print than the section title.
• To help identify parts and clarify procedure steps, there are exploded diagrams “3” at the start of each
removal and disassembly section.
• Numbers “4” are given in the order of the jobs in the exploded diagram. A number indicates a disas-
sembly step.
• Symbols “5” indicate parts to be lubricated or replaced.
Refer to “SYMBOLS”.
• A job instruction chart “6” accompanies the exploded diagram, providing the order of jobs, names of
parts, notes in jobs, etc.
• Jobs “7” requiring more information (such as special tools and technical data) are described sequen-
tially.

3 7
4

5 2

6
EAS20101

SYMBOLS
The following symbols are used in this manual for easier understanding.
TIP
The following symbols are not relevant to every vehicle.

SYMBOL DEFINITION SYMBOL DEFINITION

Serviceable with engine mounted Gear oil

reparable con motor puesto G aceite de engranajes

Filling fluid Molybdenum disulfide oil

liquido de relleno M aceite de disolfuro

Lubricant Brake fluid

lubricante BF liquido de frenos

Special tool B Wheel bearing grease

herramienta expecial

Tightening torque LS Lithium-soap-based grease

grasa de jabón de litio
T.

par de apriete
R.

Wear limit, clearance M Molybdenum disulfide grease

juego limite desgaste grasa de sulfuro de molibdeno

Engine speed S Silicone grease

velocidad de motor grasa de silicona

Electrical data Apply locking agent (LOCTITE®).

LT
datos electricos aplicar loctite

Engine oil New Replace the part with a new one.

E aceite de motor remplazar pieza
EAS20110

TABLE OF CONTENTS
GENERAL INFORMATION 1
SPECIFICATIONS 2
PERIODIC CHECKS AND
ADJUSTMENTS 3
CHASSIS 4
ENGINE 5
COOLING SYSTEM 6
FUEL SYSTEM 7
ELECTRICAL SYSTEM 8
TROUBLESHOOTING 9
 GENERAL INFORMATION

IDENTIFICATION ............................................................................................ 1-1

VEHICLE IDENTIFICATION NUMBER ..................................................... 1-1
MODEL LABEL.......................................................................................... 1-1

FEATURES...................................................................................................... 1-2
1
OUTLINE OF THE FI SYSTEM................................................................. 1-2
FI SYSTEM................................................................................................ 1-3

INSTRUMENT FUNCTIONS............................................................................ 1-4

IMPORTANT INFORMATION ......................................................................... 1-8

PREPARATION FOR REMOVAL AND DISASSEMBLY........................... 1-8
REPLACEMENT PARTS........................................................................... 1-8
GASKETS, OIL SEALS AND O-RINGS .................................................... 1-8
LOCK WASHERS/PLATES AND COTTER PINS ..................................... 1-8
BEARINGS AND OIL SEALS .................................................................... 1-9
CIRCLIPS .................................................................................................. 1-9

CHECKING THE CONNECTIONS ................................................................ 1-10

SPECIAL TOOLS .......................................................................................... 1-11

 IDENTIFICATION

EAS20130

IDENTIFICATION
EAS20140

VEHICLE IDENTIFICATION NUMBER

The vehicle identification number “1” is stamped
into the frame.

EAS20150

MODEL LABEL
The model label “1” is affixed to the location
shown. This information will be needed to order
spare parts.

1-1
 FEATURES

EAS20170

FEATURES
EAS37P1140

OUTLINE OF THE FI SYSTEM

The main function of a fuel supply system is to provide fuel to the combustion chamber at the optimum
air-fuel ratio in accordance with the engine operating conditions and the atmospheric temperature. In
the conventional carburetor system, the air-fuel ratio of the mixture that is supplied to the combustion
chamber is created by the volume of the intake air and the fuel that is metered by the jet used in the
respective carburetor.
Despite the same volume of intake air, the fuel volume requirement varies with the engine operating
conditions, such as acceleration, deceleration, or operating under a heavy load. Carburetors that meter
the fuel through the use of jets have been provided with various auxiliary devices, so that an optimum
air-fuel ratio can be achieved to accommodate the constant changes in the operating conditions of the
engine.
As the requirements for the engine to deliver more performance and cleaner exhaust gases increase,
it becomes necessary to control the air-fuel ratio in a more precise and finely tuned manner. To accom-
modate this need, this model has adopted an electronically controlled fuel injection (FI) system, in place
of the conventional carburetor system. This system can achieve an optimum air-fuel ratio required by
the engine at all times by using a microprocessor that regulates the fuel injection volume according to
the engine operating conditions detected by various sensors.
The adoption of the FI system has resulted in a highly precise fuel supply, improved engine response,
better fuel economy, and reduced exhaust emissions.

234

5 6 7,8,9 10 11
1

16 15 14 13 12

1. Lean angle sensor 13. Coolant temperature sensor

2. Air temperature sensor 14. Spark plug
13.Sensor de temperatura del refrigerante
3. ECU (engine control unit) 15. Fuel pump
14 bujía
4. Engine trouble warning light 16. Speed sensor 15.Bomba de combustible
5. Ignition coil 1. Sensor de ángulo de inclinación 16. Sensor de velocidad
6. Fuel injector 2. Sensor de temperatura del aire
7. Intake air pressure sensor 3. ECU (unidad de control del motor)
8. Throttle position sensor 4. Luz de advertencia de problemas del motor
5. Bobina de encendido
9. ISC (idle speed control) unit
6. Inyector de combustible
10. Intake air temperature sensor 7. Sensor de presión de aire de admisión
11. Crankshaft position sensor 8. Sensor de posición del acelerador
12. O2 sensor 9. Unidad ISC (control de velocidad de ralentí)
10.Sensor de temperatura del aire de admisión
11. Sensor de posición del cigüeñal
12.Sensor de O21-2
 FEATURES

EAS37P1141

FI SYSTEM
The fuel pump delivers fuel to the fuel injector via the fuel filter. The pressure regulator maintains the
fuel pressure that is applied to the fuel injector at only 250 kPa (2.50 kgf/cm², 36.3 psi). Accordingly,
when the energizing signal from the ECU energizes the fuel injector, the fuel passage opens, causing
the fuel to be injected into the intake manifold only during the time the passage remains open. There-
fore, the longer the length of time the fuel injector is energized (injection duration), the greater the vol-
ume of fuel that is supplied. Conversely, the shorter the length of time the fuel injector is energized
(injection duration), the lesser the volume of fuel that is supplied.
The injection duration and the injection timing are controlled by the ECU. Signals that are input from the
throttle position sensor, coolant temperature sensor, lean angle sensor, crankshaft position sensor, in-
take air pressure sensor, intake air temperature sensor, speed sensor and O2 sensor enable the ECU
to determine the injection duration. The injection timing is determined through the signals from the
crankshaft position sensor. As a result, the volume of fuel that is required by the engine can be supplied
at all times in accordance with the driving conditions.

7
8
2 C
6 9
3 10
A 5
4
1 11

17 12
B

16
15

14

13

1. Fuel pump 1. Bomba de combustible 14. Intake air pressure sensor sensor admisión de aire
2. Pressure regulator 2. Regulador de presión 15. Throttle body cuerpo acelerador
3. Fuel injector 3. Inyector de combustible 16. Intake air temperature sensor temperatura admision
4. Ignition coil 4. Bobina de encendido 17. Air filter case filtro del aire
5. Coolant temperature sensor 5. Sensor del refrigerante
A. Fuel system Sistema de combustible
6. ECU (engine control unit) 6. (unidad de control )
B. Air system Sistema de aire
7. ISC (idle speed control) unit velocidad relenti
C. Control system Sistema de control
8. Throttle position sensor sensor acelerador
9. Lean angle sensor sensor ángulo de inclinación
10. Speed sensor sensor de velocidad
11. O2 sensor sensor de co2
12. Catalytic converter convertidor catalitico
13. Crankshaft position sensor sensor posición cigueñal

1-3
 INSTRUMENT FUNCTIONS

EAS37P1080
• a fuel reserve tripmeter (which shows the dis-
INSTRUMENT FUNCTIONS tance traveled since the bottom segment of the
fuel meter and fuel level warning indicator
Multi-function display started flashing)
EWA37P1016
• a self-diagnosis device
WARNING
• a clock
Be sure to stop the vehicle before making • an ambient temperature display
any setting changes to the multi-function • an oil change indicator
display. Changing settings while riding can • a V-belt replacement indicator
distract the operator and increase the risk of
TIP
an accident.
• Be sure to turn the key to “ON” before using the
“SELECT” and “RESET” buttons.
1 • When the key is turned to “ON”, all of the dis-
2 play segments of the multi-function display will
3 appear and then disappear, in order to test the
electrical circuit.
4

5 Odometer and tripmeter modes

6 Pushing the “SELECT” button switches the dis-
play between the odometer mode “Odo” and the
tripmeter modes “Trip” in the following order:
1. Clock/ambient temperature display
Odo/Trip (top) → Trip (bottom)/Trip (top) →
2. Coolant temperature meter
Odo/Trip (top)
3. Fuel meter
4. Odometer/fuel reserve tripmeter
5. “SELECT” button
6. “RESET” button

1 2 3 4

When approximately 1.7 L (0.45 US gal, 0.37

Imp.gal) of fuel remains in the fuel tank, the bot-
tom segment of the fuel meter and fuel level
warning indicator will start flashing, and the dis-
1. V-belt replacement indicator “V-BELT” play will automatically change to the fuel reserve
2. Fuel level warning indicator “ ”
tripmeter mode “Trip F” and start counting the
distance traveled from that point. In that case,
3. Coolant temperature warning indicator “ ”
pushing the “SELECT” button switches the dis-
4. Oil change indicator “OIL”
play between the various tripmeter and odome-
The multi-function display is equipped with the ter modes in the following order:
following: Trip F/Trip (top) → Trip (bottom)/Trip (top) →
• a fuel meter Odo/Trip (top) → Trip F/Trip (top)
• a coolant temperature meter
• an odometer
• two tripmeters (which show the distance trav-
eled since they were last set to zero)

1-4
 INSTRUMENT FUNCTIONS

top segment and coolant temperature warning

indicator flash, stop the vehicle and let the en-
gine cool.

1. Fuel reserve tripmeter

ECA37P1034

NOTICE
Do not continue to operate the engine if it is
overheating.

Oil change indicator “OIL”

This indicator flashes at the initial 1000 km (600
mi), then at 6000 km (3500 mi) and every 6000
km (3500 mi) thereafter for YP125R, or at 4000
To reset a tripmeter, select it by pushing the “SE- km (2500 mi) and every 3000 km (1800 mi)
LECT” button until “Trip” or “Trip F” begins flash- thereafter for YP250R to indicate that the engine
ing (“Trip” or “Trip F” will only flash for five oil should be changed. After changing the en-
seconds). While “Trip” or “Trip F” is flashing, gine oil, reset the oil change indicator.
push the “RESET” button for at least one sec- If the engine oil is changed before the oil change
ond. If you do not reset the fuel reserve tripmeter indicator comes on (i.e. before the periodic oil
manually, it will reset itself automatically and the change interval has been reached), the indicator
display will return to the prior mode after refuel- must be reset after the oil change for the next
ing and traveling 5 km (3 mi). periodic oil change to be indicated at the correct
TIP time. To reset the oil change indicator before the
The display cannot be changed back to “Trip F” periodic oil change interval has been reached,
after pushing the “RESET” button. follow the above procedure, but note that the in-
dicator will come on for 1.4 seconds after releas-
ing the “OIL CHANGE” button, otherwise repeat
Fuel meter
the procedure.
With the key in the “ON” position, the fuel meter
To reset the oil change indicator
indicates the amount of fuel in the fuel tank. The
1. Turn the key to “ON”.
display segments of the fuel meter disappear to-
2. Hold the “OIL CHANGE” button pushed for
wards “E” (Empty) as the fuel level decreases.
15 to 20 seconds.
When the fuel level reaches the bottom segment
near “E”, the fuel level warning indicator and the
bottom segment will flash. Refuel as soon as
possible.

Coolant temperature meter

With the key in the “ON” position, the coolant
temperature meter indicates the temperature of
the coolant. The coolant temperature varies with 1
changes in the weather and engine load. If the

1. “OIL CHANGE” button

1-5
 INSTRUMENT FUNCTIONS

indicator must be reset after the V-belt replace-

ment for the next periodic V-belt replacement to
be indicated at the correct time.

Self-diagnosis device
This model is equipped with a self-diagnosis de-
vice for various electrical circuits.
If a problem is detected in any of those circuits,
1 the multi-function display will indicate a fault
code.
1. “OIL CHANGE” button If the multi-function display indicates such a fault
3. Release the “OIL CHANGE” button, and the code, note the code number, and then check the
oil change indicator will go off. vehicle.
The electrical circuit of the indicator can be Refer to “FUEL INJECTION SYSTEM” on page
checked according to the following procedure. 8-31.
ECA37P1035
1. Turn the key to “ON”. NOTICE
2. Check that the indicator comes on for a few
If the multi-function display indicates a fault
seconds and then goes off.
code, the vehicle should be checked as soon
3. If the indicator does not come on, check the
as possible in order to avoid engine damage.
electrical circuit.
Refer to “SIGNALING SYSTEM” on page The self-diagnosis device also detects problems
8-19. in the immobilizer system circuits.
If a problem is detected in the immobilizer sys-
V-belt replacement indicator “V-BELT” tem circuits, the immobilizer system indicator
This indicator flashes every 18000 km (10500 light will flash and the multi-function display will
mi) for the YP125R, or every 20000 km (12500 indicate a fault code when the key is turned to
mi) for the YP250R, when the V-belt needs to be “ON”.
replaced. TIP
The electrical circuit of the indicator can be If the multi-function display indicates fault code
checked according to the following procedure. 52, this could be caused by transponder interfer-
1. Turn the key to “ON”. ence. If this fault appears, try the following.
2. Check that the indicator comes on for a few
seconds and then goes off.
3. If the indicator does not come on, check the
electrical circuit.
Refer to “SIGNALING SYSTEM” on page
8-19.

To reset the V-belt replacement indicator

1. Turn the key to “ON”. 1
2. Disconnect the V-belt replacement reset cou-
pler “1” for two to ten seconds.
3. And then, connect the V-belt replacement re- 1. Fault code display
set coupler, the V-belt replacement indicator 1. Use the code re-registering key to start the
will come on for 1.4 seconds. engine.
And the V-belt replacement indicator will go
TIP
off.
Make sure there are no other immobilizer keys
TIP
close to the main switch, and do not keep more
If the V-belt is replaced before the V-belt re- than one immobilizer key on the same key ring!
placement indicator comes on (i.e. before the V-
belt replacement interval has been reached), the

1-6
 INSTRUMENT FUNCTIONS

Immobilizer system keys may cause signal inter- “SELECT” button for at least two seconds
ference, which may prevent the engine from switches the ambient temperature display to the
starting. clock display.
2. If the engine starts, turn it off, and try starting TIP
the engine with the standard keys. • If the ambient temperature falls below -10 °C,
3. If one or both of the standard keys do not start a lower temperature than -10 °C will not be dis-
the engine, re-register the standard keys. played.
If the multi-function display indicates any fault • If the ambient temperature climbs above 50 °C,
codes, note the code number, and then check a higher temperature than 50 °C will not be dis-
the vehicle. played.
Refer to “IMMOBILIZER SYSTEM” on page • The accuracy of the temperature reading may
8-61. be affected when riding slowly (approximately
under 20 km/h (12.5 mi/h)) or when stopped at
Clock mode traffic signals, railroad crossings, etc.
To set the clock:
1. Push the “SELECT” button and “RESET” but-
ton together for at least two seconds.
2. When the hour digits start flashing, push the
“RESET” button to set the hours.

3. Push the “SELECT” button, and the minute

digits will start flashing.

4. Push the “RESET” button to set the minutes.

5. Push the “SELECT” button and then release
it to start the clock.

Ambient temperature display

Pushing the “SELECT” button for at least two
seconds switches the clock display to the ambi-
ent temperature display. This display shows the
ambient temperature from -10 °C to 50 °C in 1
°C increments. The temperature displayed may
vary from the ambient temperature. Pushing the

1-7
 IMPORTANT INFORMATION

EAS20180

IMPORTANT INFORMATION
EAS20190

PREPARATION FOR REMOVAL AND

DISASSEMBLY
1. Before removal and disassembly, remove all
dirt, mud, dust and foreign material.

EAS20210

GASKETS, OIL SEALS AND O-RINGS

1. When overhauling the engine, replace all
gaskets, seals and O-rings. All gasket surfac-
es, oil seal lips and O-rings must be cleaned.
2. During reassembly, properly oil all mating
parts and bearings and lubricate the oil seal
2. Use only the proper tools and cleaning equip- lips with grease.
ment.
Refer to “SPECIAL TOOLS” on page 1-11.
3. When disassembling, always keep mated
parts together. This includes gears, cylinders,
pistons and other parts that have been “mat-
ed” through normal wear. Mated parts must
always be reused or replaced as an assem-
bly.

1. Oil
2. Lip
3. Spring
4. Grease
EAS20220

LOCK WASHERS/PLATES AND COTTER

PINS
After removal, replace all lock washers/plates
4. During disassembly, clean all of the parts and “1” and cotter pins. After the bolt or nut has been
place them in trays in the order of disassem- tightened to specification, bend the lock tabs
bly. This will speed up assembly and allow for along a flat of the bolt or nut.
the correct installation of all parts.
5. Keep all parts away from any source of fire.
EAS20200

REPLACEMENT PARTS
Use only genuine Yamaha parts for all replace-
ments. Use oil and grease recommended by
Yamaha for all lubrication jobs. Other brands
may be similar in function and appearance, but
inferior in quality.

1-8
 IMPORTANT INFORMATION

EAS20230

BEARINGS AND OIL SEALS EAS20230

COJINETES Y SELLOS DE ACEITE
Install bearings “1” and oil seals “2” so that the
manufacturer’s marks or numbers are visible.Instale los cojinetes 1 y los sellos de aceite 2 de manera que
las marcas o los números del fabricante son visibles.
When installing oil seals, lubricate the oil seal
Al instalar sellos de aceite, lubrique el sello de aceite
lips with a light coat of lithium-soap-basedlabios con una ligera capa de jabón a base de litio
grease. Oil bearings liberally when installing, if
grasa. Lubricar abundantemente los cojinetes al instalarlos, si
appropriate. adecuado.
ECA13300 AVISO
NOTICE ECA13300
Do not spin the bearing with compressed air No haga girar el cojinete con aire comprimido.
because this will damage the bearing surfac-
porque esto dañará la superficie del cojinete.
es. es.

EAS20240

CIRCLIPS
Before reassembly, check all circlips carefullyCIRCUITOS
Antes de volver a montar, compruebe todos los circlips.
and replace damaged or distorted circlips. Al-y reemplace los circlips dañados o distorsionados. Alabama-
ways replace piston pin clips after one use. formas de reemplazar los clips del pasador del pistón después de un uso.
When installing a circlip “1”, make sure the Al instalar un circlip 1, asegúrese de que
sharp-edged corner “2” is positioned oppositela esquina afilada 2 se coloca enfrente
the thrust “3” that the circlip receives. el empuje 3 que recibe el circlip.

1-9
 CHECKING THE CONNECTIONS

EAS20250

CHECKING THE CONNECTIONS Pocket tester

Check the leads, couplers, and connectors for 90890-03112
stains, rust, moisture, etc. Analog pocket tester
1. Disconnect: YU-03112-C
• Lead
• Coupler TIP
• Connector • If there is no continuity, clean the terminals.
2. Check: • When checking the wire harness, perform
• Lead steps (1) to (3).
• Coupler • As a quick remedy, use a contact revitalizer
• Connector available at most part stores.
Moisture → Dry with an air blower.
Rust/stains → Connect and disconnect sev-
eral times.

3. Check:
• All connections
Loose connection → Connect properly.
TIP
If the pin “1” on the terminal is flattened, bend it
up.

4. Connect:
• Lead
• Coupler
• Connector
TIP
Make sure all connections are tight.
5. Check:
• Continuity
(with the pocket tester)

1-10
 SPECIAL TOOLS

EAS20260

SPECIAL TOOLS
The following special tools are necessary for complete and accurate tune-up and assembly. Use only
the appropriate special tools as this will help prevent damage caused by the use of inappropriate tools
or improvised techniques. Special tools, part numbers or both may differ depending on the country.
When placing an order, refer to the list provided below to avoid any mistakes.
TIP
• For U.S.A. and Canada, use part numbers starting with “YM-”, “YU-”, or “ACC-”.
• For others, use part numbers starting with “90890-”.

Reference
Tool name/Tool No. Illustration
pages
Pocket tester 1-10, 8-75,
90890-03112 8-76, 8-77,
Analog pocket tester 8-80, 8-81,
YU-03112-C 8-82, 8-83,
Probador de bolsillo 8-84, 8-85,
90890-03112 8-86, 8-87,
Comprobador de bolsillo analógico 8-89, 8-90,
YU-03112-C 8-91
Tappet adjusting tool 3-7, 3-22
90890-01311
Six piece tappet set
YM-A5970
Herramienta de ajuste de taqués
90890-01311
Juego de taqués de seis piezas
YM-A5970
YM-A5970

ø8 ø9 ø10

ø3 ø4
FI diagnostic tool 3-8, 3-23, 8-34
90890-03182
Herramienta de diagnóstico FI
90890-03182

Timing light luz sincronizacion 3-10, 3-25

90890-03141
Inductive clamp timing light
YU-03141
luz sincronización abrazadera inductiva

Compression gauge 3-11, 3-26

90890-03081
Engine compression tester
YU-33223
probador compresión motor

1-11
 SPECIAL TOOLS

Reference
Tool name/Tool No. Illustration
pages
Steering nut wrench llave tuercas direccion 3-38, 4-59
90890-01403
Exhaust flange nut wrench
YU-A9472
llave tuerca brida escape

Damper rod holder 4-52, 4-54

90890-01294
Damping rod holder set
YM-01300
Soporte de barra amortiguadora
90890-01294
Juego de soportes para barra de amortiguación
YM-01300 YM-01300

T-handle mango T 4-52, 4-54

90890-01326
T-handle 3/8" drive 60 cm long
YM-01326

Fork seal driver weight 4-54

90890-01367
Replacement hammer
YM-A9409-7
Peso del impulsor del sello de la horquilla
90890-01367
Martillo de repuesto
YM-A9409-7/YM-A5142-4
YM-A9409-7

Fork seal driver attachment (ø38) 4-54

90890-01372
Replacement 38 mm
YM-A5142-1
accesorio impulsor sello horquilla

Yamaha bond No. 1215 5-12, 5-43,

90890-85505 5-59, 5-103,
(Three Bond No.1215®) 5-120, 6-15
bono yamaha

1-12
 SPECIAL TOOLS

Reference
Tool name/Tool No. Illustration
pages
Valve spring compressor 5-19, 5-24,
90890-04019 5-78, 5-83
YM-04019
Compresor de resorte de válvula

Valve spring compressor attachment 5-19, 5-24,

90890-04108 5-78, 5-83
Valve spring compressor adapter 22 mm
YM-04108
Accesorio de compresor de resorte de válvula
Adaptador de compresor de resorte de válvula 22 mm
Valve guide remover (ø4.5) 5-20
90890-04116
Valve guide remover (4.5 mm)
YM-04116
Extractor de guía de válvula (ø4.5)
Extractor de guía de válvula (4,5 mm)
Valve guide installer (ø4.5) 5-20
90890-04117
Valve guide installer (4.5 mm)
YM-04117
Instalador de guías de válvulas (ø4.5)
Instalador de guía de válvula (4,5 mm)
Valve guide reamer (ø4.5) 5-20
90890-04118
Valve guide reamer (4.5 mm)
YM-04118
Escariador de guía de válvula (ø4.5)
Escariador de guía de válvula (4,5 mm)
Piston pin puller set 5-26, 5-85
90890-01304
Piston pin puller
YU-01304
Juego de extractores de bulón de pistón
Extractor de bulón de pistón
YU-01304

Rotor holding tool 5-33, 5-38,

90890-01235 5-93, 5-98
Universal magneto & rotor holder
YU-01235
Herramienta de sujeción del rotor
Soporte universal para magneto y rotor
Sheave holder 5-33, 5-37,
90890-01701 5-41, 5-42,
Primary clutch holder 5-43, 5-93,
YS-01880-A 5-97, 5-101,
soporte de polea 5-102
Soporte de embrague primario

1-13
 SPECIAL TOOLS

Reference
Tool name/Tool No. Illustration
pages
Locknut wrench 5-33, 5-37,
90890-01348 5-93, 5-97
YM-01348
llave de contratuerca

Clutch spring holder 5-34, 5-37,

90890-01337 5-94, 5-97
Soporte de resorte de embrague

Clutch spring holder arm 5-34, 5-37,

90890-01464 5-94, 5-97
Brazo porta resorte de embrague

Oil seal guide (ø41) 5-36, 5-96

90890-01396
Guía del sello de aceite (ø41)

Flywheel puller 5-41, 5-101

90890-01362
Heavy duty puller
YU-33270-B
Extractor de volante
extractor de servicio pesado
Digital circuit tester 5-46, 5-106,
90890-03174 8-88
Model 88 Multimeter with tachometer
YU-A1927
Probador de circuitos digitales
Multímetro modelo 88 con tacómetro

1-14
 SPECIAL TOOLS

Reference
Tool name/Tool No. Illustration
pages
Crankcase separating tool 5-56, 5-117
90890-01135
Crankcase separator
YU-01135-B
Herramienta para separar el cárter
Separador de cárter

Crankshaft installer pot 5-58, 5-59,

90890-01274 5-119, 5-120
Installing pot
YU-90058
Olla de instalación del cigüeñal
Instalación de olla
YU-90058/YU-90059

Crankshaft installer bolt 5-58, 5-59,

90890-01275 5-119, 5-120
Bolt
YU-90060
Perno de instalación del cigüeñal
Tornillo
Adapter (M14) 5-58, 5-59,
90890-01478 5-119
Adapter #6
YM-90066
Adaptador (M14)
Adaptador #6
Fork seal driver attachment 5-58
90890-01186
Replacement 27 mm
YM-A9409-1
Accesorio del impulsor del sello de la horquilla
Reemplazo 27mm
Slide hammer bolt 5-74
90890-01083
Slide hammer bolt 6 mm
YU-01083-1
Perno de martillo deslizante
Perno de martillo deslizante 6 mm

1-15
 SPECIAL TOOLS

Reference
Tool name/Tool No. Illustration
pages
Weight 5-74
90890-01084
YU-01083-3
Peso

YU-01083-3

Valve guide remover (ø6) 5-79

90890-04064
Valve guide remover (6.0 mm)
YM-04064-A
Extractor de guía de válvula (ø6)
Extractor de guía de válvula (6,0 mm)
Valve guide installer (ø6) 5-79
90890-04065
Valve guide installer (6.0 mm)
YM-04065-A
Extractor de guía de válvula (ø6)
Extractor de guía de válvula (6,0 mm)
Valve guide reamer (ø6) 5-79
90890-04066
Valve guide reamer (6.0 mm)
YM-04066
Instalador de guías de válvulas (ø6)
Instalador de guía de válvula (6,0 mm)
Yamaha grease G 5-91
90793-40016
grasa yamaha

Spacer (crankshaft installer) 5-119

90890-04081
Pot spacer
YM-91044
Espaciador (instalador de cigüeñal)
Espaciador de ollas
YM-91044

1-16
 SPECIAL TOOLS

Reference
Tool name/Tool No. Illustration
pages
Adapter (M16) Adaptador (M16) 5-120
90890-01280 Adaptador #7
Adapter #7
YM-90067

Spacer 5-120
90890-01288
espaciador

Mechanical seal installer 6-6

90890-04145 ø30
instalador sellos mecanicos

ø10

Middle driven shaft bearing driver 6-6, 6-15

90890-04058
Bearing driver 40 mm
YM-04058
Impulsor del cojinete del eje conducido medio
Impulsor de rodamientos 40 mm
Mechanical seal installer 6-15
90890-04132
Water pump seal installer
YM-33221-A
Instalador de sellos mecanicos
Instalador de sellos de bomba de agua
Fuel sender wrench 7-3, 7-4
90890-11098
Llave de emisor de combustible

Pressure gauge 7-4

90890-03153
YU-03153
Manómetro

Fuel pressure adapter 7-4

90890-03181
Adaptador de presión de combustible

Ignition checker 8-83

90890-06754
Oppama pet-4000 spark checker
YM-34487
Comprobador de encendido
Comprobador de chispa Oppama pet-4000

1-17
 SPECIAL TOOLS

Reference
Tool name/Tool No. Illustration
pages
Test harness-lean angle sensor (6P) 8-84
90890-03209
Sensor de ángulo de inclinación
del arnés de prueba (6P)

Test harness 8-89

90890-03204
Arnés de prueba

1-18
 SPECIAL TOOLS

1-19
 SPECIFICATIONS

GENERAL SPECIFICATIONS (YP125R)........................................................ 2-1

ENGINE SPECIFICATIONS (YP125R) ........................................................... 2-2

CHASSIS SPECIFICATIONS (YP125R) ......................................................... 2-9

ELECTRICAL SPECIFICATIONS (YP125R) ................................................ 2-12

TIGHTENING TORQUES (YP125R) ............................................................. 2-15

2
GENERAL TIGHTENING TORQUE SPECIFICATIONS......................... 2-15
ENGINE TIGHTENING TORQUES......................................................... 2-16
CHASSIS TIGHTENING TORQUES....................................................... 2-18

LUBRICATION POINTS AND LUBRICANT TYPES (YP125R).................... 2-21

ENGINE................................................................................................... 2-21
CHASSIS................................................................................................. 2-23

LUBRICATION SYSTEM DIAGRAMS (YP125R) ......................................... 2-25

COOLING SYSTEM DIAGRAMS (YP125R) ................................................. 2-27

CABLE ROUTING (YP125R) ........................................................................ 2-29

GENERAL SPECIFICATIONS (YP250R)...................................................... 2-47

ENGINE SPECIFICATIONS (YP250R) ......................................................... 2-48

CHASSIS SPECIFICATIONS (YP250R) ....................................................... 2-56

ELECTRICAL SPECIFICATIONS (YP250R) ................................................ 2-59

TIGHTENING TORQUES (YP250R) ............................................................. 2-62

GENERAL TIGHTENING TORQUE SPECIFICATIONS......................... 2-62
ENGINE TIGHTENING TORQUES......................................................... 2-63
CHASSIS TIGHTENING TORQUES....................................................... 2-66

LUBRICATION POINTS AND LUBRICANT TYPES (YP250R).................... 2-69

ENGINE................................................................................................... 2-69
CHASSIS................................................................................................. 2-71
COOLING SYSTEM DIAGRAMS (YP250R) ................................................. 2-73

CABLE ROUTING (YP250R) ........................................................................ 2-75

 GENERAL SPECIFICATIONS (YP125R)

EAS37P1117

GENERAL SPECIFICATIONS (YP125R)

Model
Model 39D1 (YAMAHA)
39D3 (MBK)

Dimensions
Overall length Longitud total 2201 mm (86.7 in)
Overall width Ancho promedio 776 mm (30.6 in)
Overall height Altura total 1337 mm (52.6 in)
Seat height Altura del asiento 792 mm (31.2 in)
Wheelbase distancia entre ejes 1545 mm (60.8 in)
Ground clearance Claridad del piso 134 mm (5.30 in)
Minimum turning radius Radio de giro mínimo 1805 mm (71.1 in)

Weight Peso
With oil and fuel Con aceite y combustible 171.6 kg (378 lb)
Maximum load Carga máxima 186 kg (410 lb)

2-1
 ENGINE SPECIFICATIONS (YP125R)

EAS37P1118

ENGINE SPECIFICATIONS (YP125R)

Engine
Engine type Liquid cooled 4-stroke, SOHC
Displacement 124 cm³
Cylinder arrangement Forward-inclined single cylinder
Bore × stroke 52.0 × 58.6 mm (2.05 × 2.31 in)
Compression ratio 11.20 :1
Standard compression pressure (at sea level) 550 kPa/680 r/min (5.5 kgf/cm²/680 r/min, 78.2
psi/680 r/min)
Minimum–maximum 480–620 kPa (4.8–6.2 kgf/cm², 68.3–88.2 psi)
Starting system Electric starter

Fuel Solo gasolina normal sin plomo

Recommended fuel Combustible Regular unleaded gasoline only
Combustible recomendado
Fuel tank capacity Capacidad del tanque de combustible11.8 L (3.12 US gal, 2.60 Imp.gal)
Fuel reserve amount de reserva de combustible 1.7 L (0.45 US gal, 0.37 Imp.gal)

Engine oil
Lubrication system Wet sump
Type SAE 10W-30, SAE 10W-40, SAE 15W-40, SAE
20W-40 or SAE 20W-50
Recommended engine oil grade API service SG type or higher, JASO standard
MA
Engine oil quantity
Total amount 1.60 L (1.69 US qt, 1.41 Imp.qt)
Without oil filter element replacement 1.40 L (1.48 US qt, 1.23 Imp.qt)
With oil filter element replacement 1.50 L (1.59 US qt, 1.32 Imp.qt)

Final transmission oil

Type SAE 10W-30 type SE motor oil
Quantity 0.21 L (0.22 US qt, 0.18 Imp.qt)
Quantity (disassembled) 0.23 L (0.24 US qt, 0.20 Imp·qt)

Oil filter
Oil filter type Paper

Oil pump
Oil pump type Trochoid
Inner-rotor-to-outer-rotor-tip clearance Less than 0.15 mm (0.0059 in)
Limit 0.23 mm (0.0091 in)
Outer-rotor-to-oil-pump-housing clearance 0.013–0.018 mm (0.0005–0.0007 in)
Limit 0.25 mm (0.0098 in)
Oil-pump-housing-to-inner-and-outer-rotor
clearance 0.06–0.11 mm (0.0024–0.0043 in)
Limit 0.18 mm (0.0071 in)

Cooling system
Radiator capacity (including all routes) 1.00 L (1.06 US qt, 0.88 Imp.qt)
Coolant reservoir capacity (up to the maximum level
mark) 0.25 L (0.26 US qt, 0.22 Imp.qt)

2-2
 ENGINE SPECIFICATIONS (YP125R)

Radiator cap opening pressure 100.0–120.0 kPa (1.00–1.20 kgf/cm², 14.5–17.4

psi)
Thermostat Termostato
Valve opening temperature 70.5–73.5 °C (158.9–164.3 °F) Temperatura de apertura de la válvula
Valve full open temperature 85.0 °C (185.0 °F) Temperatura de apertura total de la válvula
Valve lift (full open) Elevación de válvula (totalmente abierta)3.0 mm (0.12 in)
Radiator core Núcleo del radiador
Width Ancho 244.0 mm (9.61 in)
Height Altura 128.9 mm (5.07 in)
Depth Profundidad 22.0 mm (0.87 in)
Water pump Bomba de agua Bomba centrífuga de aspiración simple
Water pump type Tipo de bomba de agua Single suction centrifugal pump
Reduction ratio Relación de reducción 16/38 (0.42)
Impeller shaft tilt limit 0.15 mm (0.0059 in)
Límite de inclinación del eje del impulsor
Spark plug (s)
Manufacturer/model NGK/CPR9EA-9
Spark plug gap 0.8–0.9 mm (0.031–0.035 in)

Cylinder head
Volume 9.90–10.50 cm³ (0.60–0.64 cu.in)
Warpage limit 0.05 mm (0.0020 in)

Camshaft
Drive system Sistema de manejo Chain drive (left)
Camshaft lobe dimensions Dimensiones del lóbulo del árbol de levas
Intake A Admisión A 30.225–30.325 mm (1.1900–1.1939 in)
Limit Límite 30.125 mm (1.1860 in)
Intake B Admisión B 25.064–25.164 mm (0.9868–0.9907 in)
Limit Límite 24.964 mm (0.9828 in)
Exhaust A Escape A 30.261–30.361 mm (1.1914–1.1953 in)
Limit Límite 30.161 mm (1.1874 in)
Exhaust B Escape B 25.121–25.221 mm (0.9890–0.9930 in)
Limit 25.021 mm (0.9851 in)
Límite

2-3
 ENGINE SPECIFICATIONS (YP125R)

Camshaft runout limit 0.030 mm (0.0012 in)

Timing chain
Tensioning system Automatic

Rocker arm/rocker arm shaft

Rocker arm inside diameter 9.985–10.000 mm (0.3931–0.3937 in)
Limit 10.015 mm (0.3943 in)
Rocker arm shaft outside diameter 9.966–9.976 mm (0.3924–0.3928 in)
Limit 9.940 mm (0.3913 in)
Rocker-arm-to-rocker-arm-shaft clearance 0.009–0.034 mm (0.0004–0.0013 in)
Limit 0.075 mm (0.0030 in)

Valve, valve seat, valve guide

Valve clearance (cold) Juego de válvulas (frío)
Intake Consumo 0.10–0.14 mm (0.0039–0.0055 in)
Exhaust Escape 0.22–0.26 mm (0.0087–0.0102 in)
Valve dimensions Dimensiones de la válvula
Valve head diameter A (intake) A (admisión) 19.40–19.60 mm (0.7638–0.7717 in)
Valve head diameter A (exhaust) A (escape) 16.90–17.10 mm (0.6654–0.6732 in)

Valve face width B (intake) 1.680–2.120 mm (0.0661–0.0835 in)

Valve face width B (exhaust) 1.480–2.190 mm (0.0583–0.0862 in)
Ancho de cara de válvula B (admisión)
Ancho de cara de válvula B (escape)
B

Valve seat width C (intake) 0.90–1.10 mm (0.0354–0.0433 in)

Limit 1.6 mm (0.06 in)
Valve seat width C (exhaust) 0.90–1.10 mm (0.0354–0.0433 in)
Limit 1.6 mm (0.06 in)
Ancho del asiento de la válvula C (admisión) )
Límite
C Ancho del asiento de la válvula C
Límite

Valve margin thickness D (intake) 0.85–1.15 mm (0.0335–0.0453 in)

Limit 0.5 mm (0.02 in)
Valve margin thickness D (exhaust) 0.85–1.15 mm (0.0335–0.0453 in)
Grosor del margen de la válvula D (admisión)
Límite
Grosor del margen de la válvula D (escape)

2-4
 ENGINE SPECIFICATIONS (YP125R)

Limit 0.5 mm (0.02 in)

Valve stem diameter (intake) 4.475–4.490 mm (0.1762–0.1768 in)

Limit 4.445 mm (0.1750 in)
Valve stem diameter (exhaust) 4.460–4.475 mm (0.1756–0.1762 in)
Limit 4.430 mm (0.1744 in)
Valve guide inside diameter (intake) 4.500–4.512 mm (0.1772–0.1776 in)
Limit 4.550 mm (0.1791 in)
Valve guide inside diameter (exhaust) 4.500–4.512 mm (0.1772–0.1776 in)
Limit 4.550 mm (0.1791 in)
Valve-stem-to-valve-guide clearance (intake) 0.010–0.037 mm (0.0004–0.0015 in)
Limit 0.080 mm (0.0031 in)
Valve-stem-to-valve-guide clearance (exhaust) 0.025–0.052 mm (0.0010–0.0020 in)
Limit 0.100 mm (0.0039 in)
Valve stem runout 0.010 mm (0.0004 in)

Cylinder head valve seat width (intake) 0.90–1.10 mm (0.0354–0.0433 in)

Limit 1.6 mm (0.06 in)
Cylinder head valve seat width (exhaust) 0.90–1.10 mm (0.0354–0.0433 in)
Limit 1.6 mm (0.06 in)

Valve spring
Free length (intake) 41.71 mm (1.64 in)
Limit 39.62 mm (1.56 in)
Free length (exhaust) 41.71 mm (1.64 in)
Limit 39.62 mm (1.56 in)
Installed length (intake) 35.30 mm (1.39 in)
Installed length (exhaust) 35.30 mm (1.39 in)
Spring rate K1 (intake) 23.54 N/mm (2.40 kgf/mm, 134.41 lb/in)
Spring rate K2 (intake) 36.58 N/mm (3.73 kgf/mm, 208.87 lb/in)
Spring rate K1 (exhaust) 23.54 N/mm (2.40 kgf/mm, 134.41 lb/in)
Spring rate K2 (exhaust) 36.58 N/mm (3.73 kgf/mm, 208.87 lb/in)
Installed compression spring force (intake) 140–162 N (14.28–16.52 kgf, 31.47–36.42 lbf)
Installed compression spring force (exhaust) 140–162 N (14.28–16.52 kgf, 31.47–36.42 lbf)
Spring tilt (intake) 2.5°/1.8 mm
Spring tilt (exhaust) 2.5°/1.8 mm

2-5
 ENGINE SPECIFICATIONS (YP125R)

Winding direction (intake) Clockwise

Winding direction (exhaust) Clockwise

Cylinder
Bore 52.000–52.010 mm (2.0472–2.0476 in)
Wear limit 52.110 mm (2.0516 in)
Taper limit 0.050 mm (0.0020 in)
Out of round limit 0.005 mm (0.0002 in)
Warp limit 0.05 mm (0.0020 in)

Piston
Piston-to-cylinder clearance 0.015–0.048 mm (0.0006–0.0019 in)
Limit 0.15 mm (0.0059 in)
Diameter D 51.962–51.985 mm (2.0457–2.0466 in)
Height H 5.0 mm (0.20 in)

H
D

Offset 0.50 mm (0.0197 in)

Offset direction Intake side
Piston pin bore inside diameter 14.002–14.013 mm (0.5513–0.5517 in)
Limit 14.043 mm (0.5529 in)
Piston pin outside diameter 13.995–14.000 mm (0.5510–0.5512 in)
Limit 13.975 mm (0.5502 in)
Piston-pin-to-piston-pin-bore clearance 0.002–0.018 mm (0.0001–0.0007 in)
Limit 0.068 mm (0.0027 in)

Piston ring
Top ring
Ring type Barrel
Dimensions (B × T) 0.80 × 1.90 mm (0.03 × 0.07 in)

B
T

End gap (installed) 0.10–0.25 mm (0.0039–0.0098 in)

Limit 0.50 mm (0.0197 in)
Ring side clearance 0.040–0.080 mm (0.0016–0.0031 in)
Limit 0.120 mm (0.0047 in)
2nd ring
Ring type Taper
Dimensions (B × T) 0.80 × 2.10 mm (0.03 × 0.08 in)

B
T

End gap (installed) 0.10–0.25 mm (0.0039–0.0098 in)

2-6
 ENGINE SPECIFICATIONS (YP125R)

Limit 0.60 mm (0.0236 in)

Ring side clearance 0.030–0.070 mm (0.0012–0.0028 in)
Limit 0.120 mm (0.0047 in)
Oil ring
Dimensions (B × T) 1.50 × 1.95 mm (0.06 × 0.08 in)

B
T

End gap (installed) 0.20–0.70 mm (0.0079–0.0276 in)

Ring side clearance 0.060–0.150 mm (0.0024–0.0059 in)

Crankshaft
Width A 45.95–46.00 mm (1.809–1.811 in)
Runout limit C 0.030 mm (0.0012 in)
Big end side clearance D 0.150–0.450 mm (0.0059–0.0177 in)
Big end radial clearance E 0.004–0.014 mm (0.0002–0.0006 in)

Cigüeñal
C C Límite de descentramiento
Espacio libre lateral de la cabeza de biela
Juego radial de cabeza de biela E
E
D

Clutch
Clutch type Dry, centrifugal automatic

Automatic centrifugal clutch

Clutch shoe thickness 2.0 mm (0.08 in)
Limit 1.0 mm (0.04 in)
Clutch shoe spring free length 33.0 mm (1.30 in)
Clutch housing inside diameter 135.0 mm (5.31 in)
Limit 135.5 mm (5.33 in)
Compression spring free length 112.0 mm (4.41 in)
Limit 106.4 mm (4.19 in)
Weight outside diameter 20.0 mm (0.79 in)
Limit 19.5 mm (0.77 in)
Clutch-in revolution 3500–4100 r/min
Clutch-stall revolution 5300–6300 r/min

V-belt
V-belt width 22.0 mm (0.87 in)
Limit 19.8 mm (0.78 in)

Transmission
Transmission type V-belt automatic
Primary reduction system Helical gear
Primary reduction ratio 41/14 (2.929)
Secondary reduction system Helical gear

2-7
 ENGINE SPECIFICATIONS (YP125R)

Secondary reduction ratio 44/13 (3.385)

Operation Centrifugal automatic type
Gear ratio 2.645–0.824 :1

Decompression device
Device type Auto decomp

Air filter
Air filter element Oil-coated paper element

Fuel pump
Pump type Electrical
Output pressure 250.0 kPa (2.50 kgf/cm², 36.3 psi)

Fuel injector
Model/quantity 1P51/1

Throttle body
Type/quantity EFI 1B91/1
ID mark 1B91 00

Throttle position sensor

Input voltage (at idle) 5V
Output voltage (at idle) 0.40–0.90 V

Fuel injection sensor

Crankshaft position sensor resistance 248–372 Ω at 20 °C (68 °F)
Intake air pressure sensor output voltage 3.57–3.71 V
Intake air temperature sensor resistance 2.21–2.69 kΩ at 20 °C (68 °F)
Coolant temperature sensor resistance 2.32–2.59 kΩ at 20 °C (68 °F)
310–326 Ω at 80 °C (176 °F)

Idling condition
Engine idling speed 1600–1800 r/min
CO% (muffler tailpipe) 0.5%
Intake vacuum 67.0–73.0 kPa (503–548 mmHg, 19.8–21.6
inHg)
Water temperature 80.0–90.0 °C (176.00–194.00 °F)
Oil temperature 75.0–85.0 °C (167.00–185.00 °F)
Throttle cable free play 3.0–5.0 mm (0.12–0.20 in)

2-8
 CHASSIS SPECIFICATIONS (YP125R)

EAS37P1119

CHASSIS SPECIFICATIONS (YP125R)

Chassis
Frame type Steel tube underbone
Caster angle 28.00°
Trail 100.0 mm (3.94 in)

Front wheel
Wheel type Cast wheel
Rim size 15 × MT3.5
Rim material Aluminum
Wheel travel 110.0 mm (4.33 in)
Radial wheel runout limit 1.0 mm (0.04 in)
Lateral wheel runout limit 0.5 mm (0.02 in)
Wheel axle bending limit 0.25 mm (0.01 in)

Rear wheel
Wheel type Cast wheel
Rim size 14 × MT3.75
Rim material Aluminum
Wheel travel 95.0 mm (3.74 in)
Radial wheel runout limit 1.0 mm (0.04 in)
Lateral wheel runout limit 0.5 mm (0.02 in)
Wheel axle bending limit 0.25 mm (0.01 in)

Front tire
Type Tubeless
Size 120/70–15 M/C 56P (PIRELLI)
120/70–15 M/C 56S (MICHELIN)
Manufacturer/model MICHELIN/GOLD STANDARD
PIRELLI/GTS23
Wear limit (front) 1.6 mm (0.06 in)

Rear tire
Type Tubeless
Size 140/70–14 M/C 68P (PIRELLI)
140/70–14 M/C 68S (MICHELIN)
Manufacturer/model MICHELIN/GOLD STANDARD
PIRELLI/GTS24
Wear limit (rear) 1.6 mm (0.06 in)

Tire air pressure (measured on cold tires)

Loading condition 0–90 kg (0–198 lb)
Front 190 kPa (1.90 kgf/cm², 28 psi)
Rear 220 kPa (2.20 kgf/cm², 32 psi)
Loading condition 90 kg–maximum load
Front 210 kPa (2.10 kgf/cm², 30 psi)
Rear 250 kPa (2.50 kgf/cm², 36 psi)

Front brake
Type Single disc brake
Operation Right hand operation

2-9
 CHASSIS SPECIFICATIONS (YP125R)

Front disc brake

Disc outside diameter × thickness 267.0 × 5.0 mm (10.51 × 0.20 in)
Brake disc thickness limit 4.5 mm (0.18 in)
Brake disc deflection limit 0.15 mm (0.0059 in)
Brake pad lining thickness (inner) 5.0 mm (0.20 in)
Limit 1.5 mm (0.06 in)
Brake pad lining thickness (outer) 5.0 mm (0.20 in)
Limit 1.5 mm (0.06 in)
Master cylinder inside diameter 12.70 mm (0.50 in)
Caliper cylinder inside diameter 27.00 mm × 2 (1.06 in × 2)
Recommended fluid DOT 4

Rear brake
Type Single disc brake
Operation Left hand operation
Rear disc brake
Disc outside diameter × thickness 240.0 × 5.0 mm (9.45 × 0.20 in)
Brake disc thickness limit 4.5 mm (0.18 in)
Brake disc deflection limit 0.25 mm (0.0098 in)
Brake pad lining thickness (inner) 7.3 mm (0.29 in)
Limit 0.8 mm (0.03 in)
Brake pad lining thickness (outer) 7.3 mm (0.29 in)
Limit 0.8 mm (0.03 in)
Master cylinder inside diameter 11.0 mm (0.43 in)
Caliper cylinder inside diameter 32.00 mm × 2 (1.26 in × 2)
Recommended fluid DOT 4

Steering
Steering bearing type Ball and angular bearings
Center to lock angle (left) 57.0°
Center to lock angle (right) 57.0°
No./size of steel balls
(Upper) 14 pcs
(Lower) 18 pcs

Front suspension
Type Telescopic fork
Spring/shock absorber type Coil spring/oil damper
Front fork travel 110.0 mm (4.33 in)
Fork spring free length 340.0 mm (13.39 in)
Limit 333.0 mm (13.11 in)
Installed length 285.1 mm (11.22 in)
Spring rate K1 12.00 N/mm (1.22 kgf/mm, 68.52 lb/in)
Spring rate K2 16.60 N/mm (1.69 kgf/mm, 94.79 lb/in)
Spring stroke K1 0–77.0 mm (0–3.03 in)
Spring stroke K2 77.0–110.0 mm (3.03–4.33 in)
Inner tube outer diameter 35.0 mm (1.38 in)
Inner tube bending limit 0.2 mm (0.01 in)
Optional spring available No
Recommended oil Fork oil 10W or equivalent
Quantity 128.0 cm³ (4.33 US oz, 4.51 Imp.oz)
Level 109.0 mm (4.29 in)

2-10
 CHASSIS SPECIFICATIONS (YP125R)

Rear suspension
Type Unit swing
Spring/shock absorber type Coil spring/oil damper
Rear shock absorber assembly travel 95.0 mm (3.74 in)
Spring free length 274.0 mm (10.79 in)
Installed length 241.3 mm (9.50 in)
Spring rate K1 8.00 N/mm (0.82 kgf/mm, 45.68 lb/in)
Spring rate K2 17.30 N/mm (1.76 kgf/mm, 98.78 lb/in)
Spring stroke K1 0–47.5 mm (0–1.87 in)
Spring stroke K2 47.5–95.0 mm (1.87–3.74 in)
Optional spring available No
Spring preload adjusting positions
Minimum 1
Standard 2
Maximum 4

Swingarm
Swingarm end free play limit (radial) 1.0 mm (0.04 in)
Swingarm end free play limit (axial) 1.0 mm (0.04 in)

2-11
 ELECTRICAL SPECIFICATIONS (YP125R)

EAS37P1120

ELECTRICAL SPECIFICATIONS (YP125R)

Voltage
System voltage 12 V

Ignition system
Ignition system TCI (digital)
Advancer type Digital
Ignition timing (B.T.D.C.) 8.0°/1700 r/min

Engine control unit

Model/manufacturer 39D0/YAMAHA

Ignition coil
Minimum ignition spark gap 6.0 mm (0.24 in)
Primary coil resistance 2.16–2.64 Ω at 20 °C (68 °F)
Secondary coil resistance 8.64–12.96 kΩ at 20 °C (68 °F)

Spark plug cap

Material Resin
Resistance 10.0 kΩ

AC magneto
Standard output 14.0 V, 245 W 5000 r/min
Stator coil resistance 0.28–0.42 Ω at 20 °C (68 °F)

Rectifier/regulator
Regulator type Semi conductor-short circuit
Regulated voltage (DC) 14.1–14.9 V
Rectifier capacity 25.0 A
Rectifier capacity (DC) 18.0 A
Withstand voltage 200.0 V

Battery
Model GTX9-BS
Voltage, capacity 12 V, 8.0 Ah
Manufacturer GS

Headlight
Bulb type Halogen bulb

Bulb voltage, wattage × quantity

Low beam headlight 12 V, 55.0 W × 1
High beam headlight 12 V, 55.0 W × 1
Auxiliary light 12 V, 5.0 W × 2
Tail/brake light 12 V, 5.0 W/21.0 W × 2
Front turn signal light 12 V, 10.0 W × 2
Rear turn signal light 12 V, 10.0 W × 2
License plate light 12 V, 5.0 W × 1
Meter lighting 12 V, 2.0 W × 3

2-12
 ELECTRICAL SPECIFICATIONS (YP125R)

Indicator lights
Turn signal indicator light 12 V, 1.4 W × 2
High beam indicator light 12 V, 1.4 W × 1
Engine trouble warning light 12 V, 1.4 W × 1
Immobilizer system indicator light LED

Electric starting system

System type Constant mesh

Starter motor
Power output 0.25 kW
Armature coil resistance 0.0378–0.0462 Ω
Brush overall length 7.0 mm (0.28 in)
Limit 3.50 mm (0.14 in)
Brush spring force 3.92–5.88 N (400–600 gf, 14.11–21.17 oz)
Commutator diameter 17.6 mm (0.69 in)
Limit 16.6 mm (0.65 in)
Mica undercut (depth) 1.35 mm (0.05 in)

Starter relay
Amperage 180.0 A

Horn
Horn type Plane
Quantity 1 pc
Maximum amperage 3.0 A
Coil resistance 1.4 Ω at 20 °C (68 °F)
Performance 105–118 dB/2m

Turn signal relay

Relay type Full transistor
Built-in, self-canceling device No
Turn signal flashing frequency 75–95 cycles/min
Wattage 21 W × 2.0 + 3.4 W

Fuel sender unit

Sender unit resistance (full) 20.0 Ω
Sender unit resistance (empty) 140.0 Ω

Starting circuit cut-off relay

Diode Yes

Fuses
Main fuse 30.0 A
Headlight fuse 15.0 A
Signaling system fuse 10.0 A
Ignition fuse 10.0 A
Radiator fan fuse 7.5 A
Turn signal/hazard fuse 10.0 A
ECU fuse 5.0 A
Backup fuse 5.0 A
Spare fuse 30.0 A

2-13
 ELECTRICAL SPECIFICATIONS (YP125R)

Spare fuse 15.0 A

Spare fuse 10.0 A
Spare fuse 5.0 A
Spare fuse 7.5 A

2-14
 TIGHTENING TORQUES (YP125R)

EAS37P1121

TIGHTENING TORQUES (YP125R)

EAS37P1123

GENERAL TIGHTENING TORQUE PAR DE APRIETE GENERAL

SPECIFICATIONS ESPECIFICACIONES
This chart specifies tightening torques for stan- Esta tabla especifica los pares de apriete para
dard fasteners with a standard ISO thread pitch. sujetadores dard con un paso de rosca ISO estándar.
Tightening torque specifications for special com- Especificaciones de par de apriete para componentes especiales
Se proporcionan componentes o ensamblajes para cada
ponents or assemblies are provided for each capítulo de este manual. Para evitar deformaciones, apriete
chapter of this manual. To avoid warpage, tight- en ensambles de múltiples sujetadores en un patrón entrecruzado
en multi-fastener assemblies in a crisscross pat- tern y etapas progresivas hasta el especificado
tern and progressive stages until the specified se alcanza el par de apriete. A menos que de otro modo
tightening torque is reached. Unless otherwise especificado, las especificaciones de par de apriete re-
specified, tightening torque specifications re- quire hilos limpios y secos. Los componentes deben ser
a temperatura ambiente.
quire clean, dry threads. Components should be
at room temperature.

A. Distance between flats

B. Outside thread diameter

General tightening
A (nut) B (bolt) torques
tuerca tornillo Nm m·kgf ft·lbf
10 mm 6 mm 6 0.6 4.3
12 mm 8 mm 15 1.5 11
14 mm 10 mm 30 3.0 22
17 mm 12 mm 55 5.5 40
19 mm 14 mm 85 8.5 61
22 mm 16 mm 130 13.0 94

2-15
 TIGHTENING TORQUES (YP125R)

EAS37P1122

ENGINE TIGHTENING TORQUES

Thread
Item articulo Q’ty Tightening torque Remarks
size par de apriete
cant
Exhaust pipe nut tuerca tubo escape M8 2 20 Nm (2.0 m·kgf, 14 ft·lbf)
Muffler bolt perno silenciador M10 3 53 Nm (5.3 m·kgf, 38 ft·lbf)
Muffler joint bolt unión silenciador M8 1 14 Nm (1.4 m·kgf, 10 ft·lbf)
O2 sensor sensor co2 M18 1 45 Nm (4.5 m·kgf, 32 ft·lbf)
Oil check bolt control de aceite M6 1 7 Nm (0.7 m·kgf, 5.1 ft·lbf)
Cylinder head cover bolt P.tapa.culata M6 5 10 Nm (1.0 m·kgf, 7.2 ft·lbf)
Cylinder head nut tuerca culata M8 4 22 Nm (2.2 m·kgf, 16 ft·lbf) E

Cylinder head bolt perno culata M6 2 10 Nm (1.0 m·kgf, 7.2 ft·lbf)

Cylinder head stud bolt tornillo culata M8 4 13 Nm (1.3 m·kgf, 9.4 ft·lbf)
Exhaust pipe stud bolt T..tubo escape M8 2 15 Nm (1.5 m·kgf, 11 ft·lbf)
Yamaha
Timing chain tensioner bolt M6 2 10 Nm (1.0 m·kgf, 7.2 ft·lbf) bond No.
Perno del tensor de la cadena de distribución 1215®
Spark plug Bujia M10 1 13 Nm (1.3 m·kgf, 9.4 ft·lbf)
sensor
refrigerante
Coolant temperature sensor M12 1 18 Nm (1.8 m·kgf, 13 ft·lbf)
Camshaft sprocket bolt perno Piñón M8 1 30 Nm (3.0 m·kgf, 22 ft·lbf)
arboll de levas
Camshaft retainer bolt perno retención M6 2 7 Nm (0.7 m·kgf, 5.1 ft·lbf) LT
árbol de levas
Valve clearance adjusting screw
M5 4 7 Nm (0.7 m·kgf, 5.1 ft·lbf)
locknut tuerca tornillo ajuste valvulas
perno drenaje Coolant drain bolt (cylinder) M6 1 7 Nm (0.7 m·kgf, 5.1 ft·lbf)
refrigerante
perno tapa
V-belt case cover bolt caja correa
M6 2 7 Nm (0.7 m·kgf, 5.1 ft·lbf)
V-belt case bolt perno caja correa M6 8 10 Nm (1.0 m·kgf, 7.2 ft·lbf)
V-belt case air duct bolt perno conducto
aire caja correa
M6 3 7 Nm (0.7 m·kgf, 5.1 ft·lbf)
Primary sheave nut tuerca polea M12 1 55 Nm (5.5 m·kgf, 40 ft·lbf)
primaria
Secondary sheave nut tuerca polea M14 1 60 Nm (6.0 m·kgf, 43 ft·lbf)
secundaria
Clutch carrier nut tuerca porte embrague M36 1 90 Nm (9.0 m·kgf, 65 ft·lbf)
enchufe marca Timing mark accessing plug M16 1 8 Nm (0.8 m·kgf, 5.8 ft·lbf)
sincronizacion
Generator cover bolt perno tapa M6 9 10 Nm (1.0 m·kgf, 7.2 ft·lbf)
generador
Stator coil bolt perno bobina generador M6 3 10 Nm (1.0 m·kgf, 7.2 ft·lbf) LT

perno sensor Crankshaft position sensor bolt M6 2 10 Nm (1.0 m·kgf, 7.2 ft·lbf) LT
cigueñal
Generator rotor nut tuerca rotor M14 1 80 Nm (8.0 m·kgf, 58 ft·lbf)
generador
perno montaje Starter clutch assembly bolt M6 3 13 Nm (1.3 m·kgf, 9.4 ft·lbf) LT
embrague
Starter motor bolt perno motor M6 2 7 Nm (0.7 m·kgf, 5.1 ft·lbf)
de arranque
perno placa
Oil pump plate bolt bomba aceite
M6 2 12 Nm (1.2 m·kgf, 8.7 ft·lbf) LT

Oil pump assembly screw tornillo

bomba aceite
M5 2 4 Nm (0.4 m·kgf, 2.9 ft·lbf)
perno tapa
caja transmision
Transmission case cover bolt M8 6 16 Nm (1.6 m·kgf, 11 ft·lbf)
perno tapa Oil filter element cover bolt M6 3 10 Nm (1.0 m·kgf, 7.2 ft·lbf)
filtro aceite
Oil strainer cover tapa filtro aceite M35 1 32 Nm (3.2 m·kgf, 23 ft·lbf)

2-16
 TIGHTENING TORQUES (YP125R)

Thread
Item Q’ty Tightening torque Remarks
size
Engine oil drain bolt perno drenaje M12 1 20 Nm (2.0 m·kgf, 14 ft·lbf)
aceite motor
perno drenaje Final transmission oil drain bolt M8 1 20 Nm (2.0 m·kgf, 14 ft·lbf)
aceite trans
Crankcase bolt perno del carter M6 10 10 Nm (1.0 m·kgf, 7.2 ft·lbf)
Timing chain guide bolt (intake
M6 1 7 Nm (0.7 m·kgf, 5.1 ft·lbf)
side) perno guía cadena distribucion
perno purga
de aire
Air bleed bolt (thermostat cover) M6 1 10 Nm (1.0 m·kgf, 7.2 ft·lbf)
perno tapa
Thermostat cover bolt termostato
M6 2 10 Nm (1.0 m·kgf, 7.2 ft·lbf)
Water pump housing bolt perno carcasa
bomba agua
M6 2 10 Nm (1.0 m·kgf, 7.2 ft·lbf)
perno cubierta Water pump housing cover bolt M6 5 10 Nm (1.0 m·kgf, 7.2 ft·lbf)
bomba agua
Water pump housing plate 1 bolt M6 2 10 Nm (1.0 m·kgf, 7.2 ft·lbf) LT

perno inyector
combustible
Fuel injector assembly bolt M6 1 12 Nm (1.2 m·kgf, 8.7 ft·lbf)
Fuel injector assembly holder
M6 1 10 Nm (1.0 m·kgf, 7.2 ft·lbf)
bolt tornillo soporte inyector combustible
perno presión
aire admisión
Intake air pressure sensor bolt M6 2 8 Nm (0.8 m·kgf, 5.8 ft·lbf)
Intake air pressure sensor brack-
M6 1 10 Nm (1.0 m·kgf, 7.2 ft·lbf)
et bolt soporte sensor aire admisión y cerrojo
Intake manifold bolt perno colector M6 2 10 Nm (1.0 m·kgf, 7.2 ft·lbf)
admision
T. abrazadera Throttle body clamp screw M4 1 3 Nm (0.3 m·kgf, 2.2 ft·lbf)
acelerador
perno caja Air filter case mounting bolt M6 2 9 Nm (0.9 m·kgf, 6.5 ft·lbf) LT
filtro aire
Cylinder head tightening sequence:
Secuencia de apriete de la culata:
3
1 5

4 6
2

Muffler tightening sequence:

Secuencia de apriete del silenciador: 1

2
3

2-17
 TIGHTENING TORQUES (YP125R)

EAS37P1124

CHASSIS TIGHTENING TORQUES

Thread
Item Q’ty Tightening torque Remarks
size
Engine bracket nut M12 2 59 Nm (5.9 m·kgf, 43 ft·lbf)
Engine bracket rod nut M10 2 64 Nm (6.4 m·kgf, 46 ft·lbf)
Engine mounting nut M10 1 43 Nm (4.3 m·kgf, 31 ft·lbf)
Radiator bolt M6 2 10 Nm (1.0 m·kgf, 7.2 ft·lbf)
Filler neck bolt M6 1 7 Nm (0.7 m·kgf, 5.1 ft·lbf)
Coolant reservoir bolt M6 2 7 Nm (0.7 m·kgf, 5.1 ft·lbf)
Radiator bracket nut M6 4 10 Nm (1.0 m·kgf, 7.2 ft·lbf)
Fuel tank bolt M6 3 14 Nm (1.4 m·kgf, 10 ft·lbf)
Fuel tank bracket bolt M6 4 13 Nm (1.3 m·kgf, 9.4 ft·lbf) LT

Seat nut M6 4 10 Nm (1.0 m·kgf, 7.2 ft·lbf)

Seat hinge and storage box nut M6 1 7 Nm (0.7 m·kgf, 5.1 ft·lbf)
Seat hinge spring guide bolt M6 2 10 Nm (1.0 m·kgf, 7.2 ft·lbf)
Storage box bolt M6 2 11 Nm (1.1 m·kgf, 8.0 ft·lbf)
Grab bar bolt M8 4 23 Nm (2.3 m·kgf, 17 ft·lbf) LT

Center panel bolt M6 6 10 Nm (1.0 m·kgf, 7.2 ft·lbf)

Rear panel bolt M6 2 10 Nm (1.0 m·kgf, 7.2 ft·lbf)
Mudguard bolt M6 3 11 Nm (1.1 m·kgf, 8.0 ft·lbf) LT

Rear fender bolt M6 1 7 Nm (0.7 m·kgf, 5.1 ft·lbf)

Front cowling assembly bolt M6 1 7 Nm (0.7 m·kgf, 5.1 ft·lbf)
Battery box bolt M6 1 11 Nm (1.1 m·kgf, 8.0 ft·lbf)
Battery holder bolt M6 1 7 Nm (0.7 m·kgf, 5.1 ft·lbf)
Battery bracket bolt M8 4 30 Nm (3.0 m·kgf, 22 ft·lbf)
Windshield bracket bolt M6 2 7 Nm (0.7 m·kgf, 5.1 ft·lbf)
Windshield bracket bolt M6 2 10 Nm (1.0 m·kgf, 7.2 ft·lbf) LT

Bottom cover bolt M6 2 11 Nm (1.1 m·kgf, 8.0 ft·lbf)

Storage compartment bolt M6 1 10 Nm (1.0 m·kgf, 7.2 ft·lbf)
Footrest board bolt M6 6 7 Nm (0.7 m·kgf, 5.1 ft·lbf)
Sidestand nut M10 1 56 Nm (5.6 m·kgf, 40 ft·lbf)
Sidestand switch nut M5 2 8 Nm (0.8 m·kgf, 5.8 ft·lbf)
Front fender bolt M6 4 7 Nm (0.7 m·kgf, 5.1 ft·lbf) LT

Front wheel axle M14 1 70 Nm (7.0 m·kgf, 50 ft·lbf)

Front wheel axle pinch bolt M8 1 23 Nm (2.3 m·kgf, 17 ft·lbf)
Front brake disc bolt M6 5 12 Nm (1.2 m·kgf, 8.7 ft·lbf) LT

Rear wheel axle nut M14 1 135 Nm (13.5 m·kgf, 98 ft·lbf)

Rear brake disc bolt M8 4 23 Nm (2.3 m·kgf, 17 ft·lbf) LT

Front brake caliper bolt M8 2 40 Nm (4.0 m·kgf, 29 ft·lbf)

Front brake hose union bolt M10 2 23 Nm (2.3 m·kgf, 17 ft·lbf)

2-18
 TIGHTENING TORQUES (YP125R)

Thread
Item Q’ty Tightening torque Remarks
size
Front brake hose holder bolt M6 1 7 Nm (0.7 m·kgf, 5.1 ft·lbf)
Front brake caliper bleed screw M7 1 6 Nm (0.6 m·kgf, 4.3 ft·lbf)
Front brake pad pin cap M8 1 3 Nm (0.3 m·kgf, 2.2 ft·lbf)
Front brake pad pin M8 1 18 Nm (1.8 m·kgf, 13 ft·lbf)
Front brake caliper retaining pin M8 1 23 Nm (2.3 m·kgf, 17 ft·lbf) LT

Front brake caliper retaining pin M8 1 13 Nm (1.3 m·kgf, 9.4 ft·lbf) LT

Rear brake caliper bolt M8 2 40 Nm (4.0 m·kgf, 29 ft·lbf)

Rear brake hose union bolt
M10 2 28 Nm (2.8 m·kgf, 20 ft·lbf)
(brake caliper side)
Rear brake hose union bolt
M10 2 23 Nm (2.3 m·kgf, 17 ft·lbf)
(brake master cylinder side)
Rear brake hose holder bolt M6 1 7 Nm (0.7 m·kgf, 5.1 ft·lbf)
Rear brake caliper bleed screw M10 1 14 Nm (1.4 m·kgf, 10 ft·lbf)
Upper handlebar holder bolt M8 4 23 Nm (2.3 m·kgf, 17 ft·lbf)
Front and rear brake master cyl-
M6 4 7 Nm (0.7 m·kgf, 5.1 ft·lbf)
inder holder bolt
Front and rear brake lever nut M6 2 10 Nm (1.0 m·kgf, 7.2 ft·lbf)
Grip end M16 2 26 Nm (2.6 m·kgf, 19 ft·lbf)
Steering stem nut M20 1 120 Nm (12.0 m·kgf, 85 ft·lbf)
Upper ring nut M25 1 75 Nm (7.5 m·kgf, 54 ft·lbf) See TIP.
Lower ring nut (initial tightening
M25 1 38 Nm (3.8 m·kgf, 27 ft·lbf) See TIP.
torque)
Lower ring nut (final tightening
M25 1 22 Nm (2.2 m·kgf, 16 ft·lbf) See TIP.
torque)
Speed sensor lead holder brack-
M6 1 9 Nm (0.9 m·kgf, 6.5 ft·lbf)
et bolt
Lower bracket pinch bolt M8 4 23 Nm (2.3 m·kgf, 17 ft·lbf)
Cap bolt M29 2 45 Nm (4.5 m·kgf, 32 ft·lbf)
Damper rod bolt M10 2 30 Nm (3.0 m·kgf, 22 ft·lbf) LT

Swingarm bolt M8 2 28 Nm (2.8 m·kgf, 20 ft·lbf) See TIP.

Rear shock absorber assembly
M10 2 32 Nm (3.2 m·kgf, 23 ft·lbf)
nut (upper side)
Rear shock absorber assembly
M8 2 18 Nm (1.8 m·kgf, 13 ft·lbf)
bolt (lower side)
Ignition coil bolt M6 2 10 Nm (1.0 m·kgf, 7.2 ft·lbf)
Ignition coil bracket bolt M6 2 10 Nm (1.0 m·kgf, 7.2 ft·lbf)
ECU (engine control unit) bolt M6 2 7 Nm (0.7 m·kgf, 5.1 ft·lbf)
Rectifier/regulator bolt M6 2 7 Nm (0.7 m·kgf, 5.1 ft·lbf)
Battery terminal bolt M6 2 7 Nm (0.7 m·kgf, 5.1 ft·lbf)
Horn bolt M6 1 7 Nm (0.7 m·kgf, 5.1 ft·lbf)

2-19
 TIGHTENING TORQUES (YP125R)

TIP
Lower ring nut
1. Tighten the lower ring nut 38 Nm (3.8 m·kgf, 27 ft·lbf) with a torque wrench and the steering nut
wrench, and then loosen the nut 1/4 turn.
2. Tighten the lower ring nut 22 Nm (2.2 m·kgf, 16 ft·lbf) with a torque wrench and the steering nut
wrench.
3. Install the rubber washer and the center ring nut.
4. Finger tighten the center ring nut, align the slots of both ring nuts, and then install the lock washer.
5. Hold the lower and center ring nuts, and then tighten the upper ring nut 75 Nm (7.5 m·kgf, 54 ft·lbf)
with a torque wrench and the steering nut wrench.
TIP
Swingarm mounting bolt
1. Temporarily install the rear wheel axle nut “1”.
2. Temporarily install the swingarm mounting bolt (upper side) “2”, then the swingarm mounting bolt
(lower side) “3”.
3. Tighten the rear wheel axle nut to 135 Nm (13.5 m·kgf, 98 ft·lbf).
4. Tighten the swingarm mounting bolt (upper side), then the swingarm mounting bolt (lower side) to
28 Nm (2.8 m·kgf, 20 ft·lbf).

Swingarm tightening sequence:

Secuencia de apriete del basculante:

1
3

CONSEJO
Tuerca anular inferior
1. Apriete la tuerca anular inferior a 38 Nm (3,8 m·kgf, 27 ft·lbf) con una llave dinamométrica y la tuerca de dirección
llave y luego afloje la tuerca 1/4 de vuelta.
2. Apriete la tuerca anular inferior a 22 Nm (2,2 m·kgf, 16 ft·lbf) con una llave dinamométrica y la tuerca de dirección
llave inglesa.
3. Instale la arandela de goma y la tuerca anular central.
4. Apriete con los dedos la tuerca anular central, alinee las ranuras de ambas tuercas anulares y luego instale la arandela de seguridad.
5. Sujete las tuercas anulares inferior y central y luego apriete la tuerca anular superior a 75 Nm (7,5 m·kgf, 54 ft·lbf)
con una llave dinamométrica y la llave para tuercas de dirección.

CONSEJO
Perno de montaje del basculante
1. Instale temporalmente la tuerca del eje de la rueda trasera 1.
2. Instale temporalmente el perno de montaje del basculante (lado superior) "2", luego el perno de montaje del basculante
(lado inferior) 3.
3. Apriete la tuerca del eje de la rueda trasera a 135 Nm (13,5 m·kgf, 98 ft·lbf).
4. Apriete el perno de montaje del basculante (lado superior), luego el perno de montaje del basculante (lado inferior) para
28 Nm (2,8 m·kgf, 20 pies·lbf).

2-20
 LUBRICATION POINTS AND LUBRICANT TYPES (YP125R)

EAS37P1125

LUBRICATION POINTS AND LUBRICANT TYPES (YP125R)

EAS37P1126

ENGINE
Lubrication point Lubricant
Oil seal lips Labios del sello de aceite LS

O-rings juntas tóricas LS

Bearings Aspectos E

Cylinder head nut mounting surface Superficie de montaje de la tuerca de la culata E

Crankshaft pin pasador del cigüeñal E

Connecting rod big end thrust surface Superficie de empuje de la cabeza de biela E

Oil pump drive gear inner surface Superficie interior del engranaje impulsor de la bomba de aceite E

Camshaft sprocket inner surface Superficie interior de la rueda dentada del árbol de levas E

Piston pin and connecting rod small end Pasador de pistón y pie de biela E

Piston, piston rings, and cylinder inner surface Pistón, anillos de pistón y superficie interior del cilindro E

Crankshaft end (generator rotor side) Extremo del cigüeñal (lado del rotor del generador) E

Camshaft lobes Lóbulos del árbol de levas M

Valve stems (intake and exhaust) Vástagos de válvula (admisión y escape) M

Valve stem ends (intake and exhaust) Extremos de vástago de válvula (admisión y escape) M

Rocker arm shaft and rocker arm Eje de balancines y balancines M

Decompressor cam leva del descompresor E

Oil pump driven gear shaft Eje del engranaje conducido de la bomba de aceite M

Oil pump rotors (inner and outer) Rotores de bomba de aceite (interior y exterior) E

Collar (clutch housing) Collar (carcasa de embrague) LS

Starter clutch idle gear thrust surfaceSuperficie de empuje del engranaje intermedio del embrague de arranqueE
Starter clutch idle gear shaft surface Superficie del eje del engranaje intermedio del embrague de arranque E

Starter clutch gear thrust surface Superficie de empuje del engranaje del embrague de arranque M

Starter clutch gear inner surface Superficie interior del engranaje del embrague de arranque M

Starter clutch rollers Rodillos de embrague de arranque E

Main axle thrust surface Superficie de empuje del eje principal E

Drive axle serration Dentado del eje motriz E

BEL-RAY
Oil seal and spacer (primary sheave)
assembly lube®
BEL-RAY
O-ring (clutch housing and secondary sheave)
assembly lube®
Yamaha bond
Crankcase mating surfaces
No.1215®
Yamaha bond
Crankshaft position sensor/stator assembly lead grommet
No.1215®

2-21
 LUBRICATION POINTS AND LUBRICANT TYPES (YP125R)

Lubrication point Lubricant

Yamaha bond
Timing chain tensioner bolt
No.1215®

2-22
 LUBRICATION POINTS AND LUBRICANT TYPES (YP125R)

EAS37P1127

CHASSIS
Lubrication point Lubricant
Drive axle LS

Swingarm oil seal lips LS

Steering bearings (upper and lower) LS

Seat hinge pin LS

Front wheel oil seal lip and front wheel axle LS

Speed sensor oil seal lip LS

Brake lever pivoting point and metal-to-metal moving parts S

Rear brake pad pin S

Throttle cable end LS

Throttle grip inner surface and throttle cables LS

Handlebar grip inner surface Rubber adhesive

Sidestand pivoting point and metal-to-metal moving parts LS

Sidestand spring hook metal-to-metal moving parts LS

Centerstand shaft pivoting point and metal-to-metal moving parts LS

Centerstand spring hook metal-to-metal moving parts LS

Passenger footrest pivoting point LS

2-23
LUBRICATION POINTS AND LUBRICANT TYPES (YP125R)

2-24
 LUBRICATION SYSTEM DIAGRAMS (YP125R)

EAS37P1139

LUBRICATION SYSTEM DIAGRAMS (YP125R)

4 3 5

2-25
 LUBRICATION SYSTEM DIAGRAMS (YP125R)

1. Camshaft 1. árbol de levas

2. Crankshaft 2. Cigüeñal
3. Oil pump 3. Bomba de aceite
4. Oil filter 4. Filtro de aceite
5. Oil strainer 5. Filtro de aceite

2-26
 COOLING SYSTEM DIAGRAMS (YP125R)

EAS37P1128

COOLING SYSTEM DIAGRAMS (YP125R)

3
A

2 A

3 B

6 7
2
B
4

2-27
 COOLING SYSTEM DIAGRAMS (YP125R)

1. Coolant reservoir 1. Depósito de refrigerante

2. Coolant reservoir hose 2. Manguera del depósito de refrigerante
3. Radiator cap 3. Tapa del radiador
4. Radiator filler hose 4. Manguera de llenado del radiador
5. Radiator 5. Radiador
6. Radiator inlet hose 6. Manguera de entrada del radiador
7. Radiator outlet hose 7. Manguera de salida del radiador

2-28
 CABLE ROUTING (YP125R)

EAS37P1129

CABLE ROUTING (YP125R)

Battery (front view)

15 3

A 1

2 B

3 C
15
4

14 6

7
E 13
8 D
12
9

10

11 17 2
16

13
G
9
10
11
H

2-29
 CABLE ROUTING (YP125R)

1. Positive battery lead 1. Cable positivo de la batería

2. Meter assembly lead 2. Cable de montaje del medidor
3. Self-diagnosis signal lead 3. Cable de señal de autodiagnóstico
4. Fuse box 1 4. Caja de fusibles 1
5. Air temperature sensor lead 5. Cable del sensor de temperatura del aire
6. Fuse box 2 6. Caja de fusibles 2
7. Starter relay lead 7. Cable del relé de arranque
8. Negative battery lead 8. Cable negativo de la batería
9. Headlight lead 9. Cable de faro
10. Wire harness 10. Mazo de cables
11. Lean angle sensor lead
11. Cable del sensor de ángulo de inclinación
12. Acoplador del sensor de velocidad
12. Speed sensor coupler
13. Cable del relé de señales de giro/peligro
13. Turn signal/hazard relay lead
14. Señal de giro/relé de peligro
14. Turn signal/hazard relay 15. Batería
15. Battery 16. Cable de la caja de fusibles 2
16. Fuse box 2 lead 17. Cable de la caja de fusibles 1
17. Fuse box 1 lead A. Pase el cable positivo de la batería por debajo de la batería.
A. Route the positive battery lead under the battery cubrir.
cover. B. Dirija el cable del conjunto del medidor hacia la parte delantera del
B. Route the meter assembly lead to the front of the relé de arranque.
starter relay.
C. Pase el cable de la señal de autodiagnóstico a lo largo del
C. Route the self-diagnosis signal lead along the
negative battery lead. cable negativo de la batería.
D. Dirija el cable negativo de la batería hacia la parte trasera del
D. Route the negative battery lead to the rear of the
turn signal/hazard relay lead, lean angle sensor cable del relé de señal de giro/peligro, sensor de ángulo de inclinación
lead, and headlight lead. cable y cable del faro.
E. Route the turn signal/hazard relay lead to the rear E. Dirija el cable del relé de señal de giro/peligro hacia la parte trasera
of the lean angle sensor. del sensor de ángulo de inclinación.
F. Point the end of the plastic locking tie forward, and F. Apunte el extremo de la atadura de plástico hacia adelante y
then cut off the excess end of the tie to 0–5 mm luego corte el extremo sobrante de la atadura a 05 mm
(0–0.20 in). (00,20 pulgadas).
G. Point the end of the plastic locking tie upward, and G. Apunte el extremo de la atadura de plástico hacia arriba y
then cut off the excess end of the tie to 0–5 mm luego corte el extremo sobrante de la atadura a 05 mm
(0–0.20 in).
(00,20 pulgadas).
H. Fasten the wire harness and the other leads with a H. Sujete el mazo de cables y los otros cables con un
plastic locking tie, making sure to align the tie with
the white tape on the harness. atadura de bloqueo de plástico, asegurándose de alinear la atadura con
la cinta blanca del arnés.

2-30
 CABLE ROUTING (YP125R)

Front fork (front view)

2
1
1 2

1 2
A

7
4

6
5

2-31
 CABLE ROUTING (YP125R)

1. Speed sensor lead

1. Cable del sensor de velocidad
2. Front brake hose
2. Latiguillo de freno delantero
3. Rectifier/regulator 3. Rectificador/regulador
4. Left front turn signal light coupler 4. Acoplador del intermitente delantero izquierdo
5. Wire harness 5. Mazo de cables
6. Horn 6. Cuerno
7. Right front turn signal light coupler 7. Acoplador del intermitente delantero derecho
A. Point the end of the plastic locking tie forward, and A. Apunte el extremo de la atadura de plástico hacia adelante y
then cut off the excess end of the tie to 0–5 mm luego corte el extremo sobrante de la atadura a 05 mm
(0–0.20 in). (00,20 pulgadas).

2-32
 CABLE ROUTING (YP125R)

Front brake hose (right side view)

8
1

1
13

14

13
C 11 8

12 3

11 4
11 5
A

10

7 6

B
8 8
8

7 8

2-33
 CABLE ROUTING (YP125R)

1. Front brake hose 1. Latiguillo de freno delantero

2. Radiator fan motor relay 2. Relé del motor del ventilador del radiador
3. Starting circuit cut-off relay 3. Relé de corte del circuito de arranque
4. Speed sensor lead 4. Cable del sensor de velocidad
5. Right front turn signal light 5. Luz de señal de giro delantera derecha
6. Radiator fan motor 6. Motor del ventilador del radiador
7. Radiator fan motor lead 7. Cable del motor del ventilador del radiador
8. Wire harness 8. Mazo de cables
9. Rear brake pipe 9. Tubo de freno trasero
10. Horn leads 10. Cables de bocina
11. Starter motor lead
11. Cable del motor de arranque
12. Relé de faros
12. Headlight relay
13. Latiguillo de freno trasero
13. Rear brake hose
14. Cables del acelerador
14. Throttle cables A. Coloque la abrazadera de bloqueo de plástico sobre el marco
A. Position the plastic locking tie above the frame travesaño
cross member.
B. Apunte el extremo de la atadura de plástico hacia la derecha,
B. Point the end of the plastic locking tie to the right,
and then cut off the excess end of the tie to 0–5
y luego corte el extremo sobrante de la corbata a 0-5
mm (0–0.20 in). mm (00,20 pulgadas).
C. Point the end of the plastic locking tie forward, and C. Apunte el extremo de la atadura de plástico hacia adelante y
then cut off the excess end of the tie to 0–5 mm luego corte el extremo sobrante de la atadura a 05 mm
(0–0.20 in). (00,20 pulgadas).

2-34
 CABLE ROUTING (YP125R)

Engine (right side view)

A 7
2

1 2 3

7 6 5 4 3

2-35
 CABLE ROUTING (YP125R)

1. Seat lock cable 1. Cable de bloqueo del asiento

2. Wire harness 2. Mazo de cables
3. Ignition coil lead 3. Cable de la bobina de encendido
4. Spark plug cap 4. Tapa de bujía
5. O2 sensor 5. sensor de O2
6. Starter motor lead 6. Cable del motor de arranque
7. Rear brake hose 7. Latiguillo de freno trasero
A. Point the end of the plastic locking tie to the right, A. Apunte el extremo de la atadura de plástico hacia la derecha,
and then cut off the excess end of the tie to 0–5 y luego corte el extremo sobrante de la corbata a 0-5
mm (0–0.20 in). mm (00,20 pulgadas).

2-36
 CABLE ROUTING (YP125R)

Throttle cables (left side view)

14
2

15
6 14 3 D
16 E D
13 17 17
11 12 4

5
6 F

6 6
6

I 7
A 8
B

10

7
H
3

G
3 H 5
5

2-37
 CABLE ROUTING (YP125R)

1. Meter assembly
1. Montaje del medidor
2. ECU (engine control unit)
2. ECU (unidad de control del motor)
3. Seat lock cable 3. Cable de bloqueo del asiento
4. Immobilizer unit coupler 4. Acoplador de la unidad inmovilizadora
5. Throttle cables 5. Cables del acelerador
6. Wire harness 6. Mazo de cables
7. Sidestand switch lead 7. Cable del interruptor del caballete lateral
8. Rear brake hose 8. Latiguillo de freno trasero
9. Front brake hose 9. Latiguillo de freno delantero
10. Left front turn signal light lead 10. Cable del intermitente delantero izquierdo
11. Rectifier/regulator 11. Rectificador/regulador
12. Starter motor lead 12. Cable del motor de arranque
13. Headlight coupler 13. Acoplador de faros
14. Air temperature sensor lead 14. Cable del sensor de temperatura del aire
15. Immobilizer unit lead 15. Cable de la unidad inmovilizadora
16. Cable del interruptor principal
16. Main switch lead
17. Tapa del conector
17. Connector cover
A. Dirija el cable del interruptor del caballete lateral hacia el exterior del
A. Route the sidestand switch lead to the outside of el tubo del freno trasero.
the rear brake pipe.
B. Dirija el cable del interruptor del caballete lateral hacia el interior del
B. Route the sidestand switch lead to the inside of the marco.
frame.
C. Dirija el cable del interruptor del caballete lateral hacia el exterior
C. Route the sidestand switch lead to the outside of
the frame. el marco.
D. Position the connector cover as shown in the D. Coloque la tapa del conector como se muestra en la
illustration. ilustración.
E. Forward E. Adelante
F. Fasten the wire harness at the white tape with the F. Sujete el mazo de cables en la cinta blanca con el
holder. poseedor.
G. Point the end of the plastic locking tie to the right, G. Apunte el extremo de la atadura de plástico hacia la derecha,
and then cut off the excess end of the tie to 0–5 y luego corte el extremo sobrante de la corbata a 0-5
mm (0–0.20 in). mm (00,20 pulgadas).
H. Point the end of the plastic locking tie forward. H. Apunte el extremo de la brida de plástico hacia adelante.
I. Point the end of the plastic locking tie to the left, I. Apunte el extremo de la brida de plástico hacia la izquierda,
and then cut off the excess end of the tie to 0–5 y luego corte el extremo sobrante de la corbata a 0-5
mm (0–0.20 in). mm (00,20 pulgadas).
J. Install the air temperature sensor so that there is J. Instale el sensor de temperatura del aire de modo que haya
some slack in the air temperature sensor lead. algo de holgura en el cable del sensor de temperatura del aire.

2-38
 CABLE ROUTING (YP125R)

Engine (left side view)

2
1

2-39
 CABLE ROUTING (YP125R)

1. Wire harness 1. Mazo de cables

2. Intake air temperature sensor 2. Sensor de temperatura del aire de admisión
3. Seat lock cable 3. Cable de bloqueo del asiento
4. Left tail/brake light assembly 4. Conjunto de luz trasera izquierda/luz de freno
A. Point the end of the plastic locking tie to the left, A. Apunte el extremo de la atadura de plástico hacia la izquierda,
and then cut off the excess end of the tie to 0–5 y luego corte el extremo sobrante de la corbata a 0-5
mm (0–0.20 in). mm (00,20 pulgadas).

2-40
 CABLE ROUTING (YP125R)

Handlebar (top view)

1 2 3 4 5

17 6

16
7

8
15

14

13

12

11 10 9

2-41
 CABLE ROUTING (YP125R)

1. Radiator fan motor relay 1. Relé del motor del ventilador del radiador
2. Starting circuit cut-off relay 2. Relé de corte del circuito de arranque
3. Headlight relay 3. Relé de faros
4. Right handlebar switch lead 4. Cable del interruptor del manillar derecho
5. Front brake hose 5. Latiguillo de freno delantero
6. Fuel pump coupler 6. Acoplador de bomba de combustible
7. Fuel sender coupler 7. Acoplador emisor de combustible
8. Fuel hose 8. Manguera de combustible
9. Left handlebar switch lead 9. Cable del interruptor del manillar izquierdo
10. Rear brake hose 10. Latiguillo de freno trasero
11. ECU (engine control unit) 11. ECU (unidad de control del motor)
12. Positive battery lead 12. Cable positivo de la batería
13. Cable negativo de la batería
13. Negative battery lead
14. Caja de fusibles 1
14. Fuse box 1
15. Caja de fusibles 2
15. Fuse box 2
16. Batería
16. Battery 17. Señal de giro/relé de peligro
17. Turn signal/hazard relay A. Apunte el extremo de la atadura de plástico hacia la izquierda,
A. Point the end of the plastic locking tie to the left, y luego corte el extremo sobrante de la corbata a 0-5
and then cut off the excess end of the tie to 0–5 mm (00,20 pulgadas).
mm (0–0.20 in).

2-42
 CABLE ROUTING (YP125R)

Throttle body (top view)

B 11 14 3 10
15
13

2
11 18
3 17 16
2

12 1 2 3

11

10

9 8 A 7 6

16
3 C
12
7
4
19 3

15

2-43
 CABLE ROUTING (YP125R)

1. Rear brake pipe

2. Crankshaft position sensor/stator assembly lead
3. Wire harness 1. Tubo de freno trasero
4. ISC (idle speed control) unit coupler 2. Cable del conjunto del estator/sensor de posición del cigüeñal
5. Ground lead 3. Mazo de cables
6. Intake air temperature sensor coupler 4. Acoplador de la unidad ISC (control de velocidad de ralentí)
7. Intake air pressure sensor coupler
5. Cable de tierra
6. Acoplador del sensor de temperatura del aire de admisión
8. Seat lock cable
7. Acoplador del sensor de presión del aire de admisión
9. Fuel injector assembly
8. Cable de bloqueo del asiento
10. Radiator inlet hose 9. Conjunto del inyector de combustible
11. Starter motor lead 10. Manguera de entrada del radiador
12. Thermostat inlet hose 11. Cable del motor de arranque
13. Intake air pressure lead 12. Manguera de entrada del termostato
14. Fuel injector lead 13. Cable de presión de aire de admisión
15. Throttle position sensor lead 14. Cable del inyector de combustible
16. Coolant temperature sensor lead 15. Cable del sensor de posición del acelerador
17. ISC (idle speed control) unit lead 16. Cable del sensor de temperatura del refrigerante
18. O2 sensor lead 17. Cable de la unidad ISC (control de velocidad de ralentí)
19. Throttle body 18. Cable del sensor de O2
A. Route the seat lock cable to the inside of the
19. Cuerpo de mariposa
frame. A. Dirija el cable de bloqueo del asiento hacia el interior del
B. Point the end of the plastic locking tie to the right, marco.
and then cut off the excess end of the tie to 0–5 B. Apunte el extremo de la atadura de plástico hacia la derecha,
mm (0–0.20 in). y luego corte el extremo sobrante de la corbata a 0-5
C. Fasten the wire harness at the white tape with a mm (00,20 pulgadas).
plastic locking tie. Cut off the excess end of the tie C. Sujete el mazo de cables a la cinta blanca con un
to 0–5 mm (0–0.20 in). lazo de cierre de plástico. Cortar el extremo sobrante de la corbata.
a 0-5 mm (0-0,20 pulgadas).

2-44
 CABLE ROUTING (YP125R)

Tail/brake light (top view)

1 A

1 2

3
4

2-45
 CABLE ROUTING (YP125R)

1. Wire harness
2. Rear brake hose 1. Mazo de cables
2. Latiguillo de freno trasero
3. License plate light lead
3. Cable de luz de matrícula
4. Right tail/brake light assembly coupler
4. Acoplador del conjunto de luz trasera/luz de freno derecha
5. Left tail/brake light assembly coupler
5. Acoplador del conjunto de luz de freno/trasera izquierda
6. Seat lock cable 6. Cable de bloqueo del asiento
A. Point the end of the plastic locking tie to the right, A. Apunte el extremo de la atadura de plástico hacia la derecha,
and then cut off the excess end of the tie to 0–5
y luego corte el extremo sobrante de la corbata a 0-5
mm (0–0.20 in).
mm (00,20 pulgadas).
B. Route the license plate light lead between the
water guard and the license plate light bracket. B. Pase el cable de la luz de la matrícula entre el
protección contra el agua y el soporte de la luz de la placa de matrícula.

2-46
 GENERAL SPECIFICATIONS (YP250R)

EAS20280

GENERAL SPECIFICATIONS (YP250R)

Model
Model 37P1 (YAMAHA)

Dimensions
Overall length 2201 mm (86.7 in)
Overall width 776 mm (30.6 in)
Overall height 1337 mm (52.6 in)
Seat height 792 mm (31.2 in)
Wheelbase 1545 mm (60.8 in)
Ground clearance 134 mm (5.30 in)
Minimum turning radius 1805 mm (71.1 in)

Weight
With oil and fuel 177.4 kg (391 lb)
Maximum load 186 kg (410 lb)

2-47
 ENGINE SPECIFICATIONS (YP250R)

EAS20290

ENGINE SPECIFICATIONS (YP250R)

Engine
Engine type Liquid cooled 4-stroke, SOHC
Displacement 249 cm³
Cylinder arrangement Forward-inclined single cylinder
Bore × stroke 69.0 × 66.8 mm (2.72 × 2.63 in)
Compression ratio 10.00 :1
Standard compression pressure (at sea level) 1400 kPa/500 r/min (14.0 kgf/cm²/500 r/min,
199.1 psi/500 r/min)
Minimum–maximum 1120–1570 kPa (11.2–15.7 kgf/cm², 159.3–
223.3 psi)
Starting system Electric starter

Fuel
Recommended fuel Regular unleaded gasoline only
Fuel tank capacity 11.8 L (3.12 US gal, 2.60 Imp.gal)
Fuel reserve amount 1.7 L (0.45 US gal, 0.37 Imp.gal)

Engine oil
Lubrication system Wet sump
Type SAE 10W-30, SAE 10W-40, SAE 15W-40, SAE
20W-40 or SAE 20W-50
Recommended engine oil grade API service SF, SG type or higher, JASO
standard MA
Engine oil quantity
Total amount 1.50 L (1.59 US qt, 1.32 Imp.qt)
Periodic oil change 1.30 L (1.37 US qt, 1.14 Imp.qt)

Final transmission oil

Type SAE 10W-30 type SE motor oil
Quantity 0.25 L (0.26 US qt, 0.22 Imp.qt)

Oil filter
Oil filter type Paper

Oil pump
Oil pump type Trochoid
Inner-rotor-to-outer-rotor-tip clearance Less than 0.15 mm (0.0059 in)
Limit 0.23 mm (0.0091 in)
Outer-rotor-to-oil-pump-housing clearance 0.013–0.036 mm (0.0005–0.0014 in)
Limit 0.106 mm (0.0042 in)
Oil-pump-housing-to-inner-and-outer-rotor
clearance 0.04–0.09 mm (0.0016–0.0035 in)
Limit 0.16 mm (0.0063 in)

Cooling system
Radiator capacity (including all routes) 1.00 L (1.06 US qt, 0.88 Imp.qt)
Coolant reservoir capacity (up to the maximum level
mark) 0.25 L (0.26 US qt, 0.22 Imp.qt)
Radiator cap opening pressure 100.0–120.0 kPa (1.00–1.20 kgf/cm², 14.5–17.4
psi)

2-48
 ENGINE SPECIFICATIONS (YP250R)

Thermostat
Valve opening temperature 80.5–83.5 °C (176.9–182.3 °F)
Valve full open temperature 93.0–97.0 °C (199.4–206.6 °F)
Valve lift (full open) 3.0 mm (0.12 in)
Radiator core
Width 244.0 mm (9.61 in)
Height 128.9 mm (5.07 in)
Depth 22.0 mm (0.87 in)
Water pump
Water pump type Single suction centrifugal pump
Reduction ratio 37/22 × 25/37 (1.136)
Impeller shaft tilt limit 0.15 mm (0.0059 in)

Spark plug (s)

Manufacturer/model NGK/DPR8EA-9
Spark plug gap 0.8–0.9 mm (0.031–0.035 in)

Cylinder head
Volume 21.40–22.00 cm³ (1.31–1.34 cu.in)
Warpage limit 0.05 mm (0.0020 in)

Camshaft
Drive system Chain drive (left)
Camshaft lobe dimensions
Intake A 37.051–37.151 mm (1.4587–1.4626 in)
Limit 36.950 mm (1.4547 in)
Intake B 30.074–30.174 mm (1.1840–1.1880 in)
Limit 29.974 mm (1.1801 in)
Exhaust A 37.053–37.153 mm (1.4588–1.4627 in)
Limit 36.953 mm (1.4548 in)
Exhaust B 30.091–30.191 mm (1.1847–1.1886 in)
Limit 29.991 mm (1.1807 in)

Camshaft runout limit 0.030 mm (0.0012 in)

2-49
 ENGINE SPECIFICATIONS (YP250R)

Timing chain
Tensioning system Automatic

Rocker arm/rocker arm shaft

Rocker arm inside diameter 12.000–12.018 mm (0.4724–0.4731 in)
Limit 12.030 mm (0.4736 in)
Rocker arm shaft outside diameter 11.981–11.991 mm (0.4717–0.4721 in)
Limit 11.950 mm (0.4705 in)
Rocker-arm-to-rocker-arm-shaft clearance 0.009–0.037 mm (0.0004–0.0015 in)
Limit 0.080 mm (0.0031 in)

Valve, valve seat, valve guide

Valve clearance (cold)
Intake 0.08–0.12 mm (0.0031–0.0047 in)
Exhaust 0.16–0.20 mm (0.0063–0.0079 in)
Valve dimensions
Valve head diameter A (intake) 33.90–34.10 mm (1.3346–1.3425 in)
Valve head diameter A (exhaust) 28.40–28.60 mm (1.1181–1.1260 in)

Valve face width B (intake) 3.394–3.960 mm (0.1336–0.1559 in)

Valve face width B (exhaust) 3.394–3.960 mm (0.1336–0.1559 in)

Valve seat width C (intake) 0.90–1.10 mm (0.0354–0.0433 in)

Limit 1.6 mm (0.06 in)
Valve seat width C (exhaust) 0.90–1.10 mm (0.0354–0.0433 in)
Limit 1.6 mm (0.06 in)

Valve margin thickness D (intake) 0.80–1.20 mm (0.0315–0.0472 in)

Limit 0.5 mm (0.02 in)
Valve margin thickness D (exhaust) 0.80–1.20 mm (0.0315–0.0472 in)
Limit 0.5 mm (0.02 in)

Valve stem diameter (intake) 5.975–5.990 mm (0.2352–0.2358 in)

Limit 5.940 mm (0.2339 in)
Valve stem diameter (exhaust) 5.960–5.975 mm (0.2346–0.2352 in)
Limit 5.920 mm (0.2331 in)

2-50
 ENGINE SPECIFICATIONS (YP250R)

Valve guide inside diameter (intake) 6.000–6.012 mm (0.2362–0.2367 in)

Limit 6.050 mm (0.2382 in)
Valve guide inside diameter (exhaust) 6.000–6.012 mm (0.2362–0.2367 in)
Limit 6.050 mm (0.2382 in)
Valve-stem-to-valve-guide clearance (intake) 0.010–0.037 mm (0.0004–0.0015 in)
Limit 0.080 mm (0.0031 in)
Valve-stem-to-valve-guide clearance (exhaust) 0.025–0.052 mm (0.0010–0.0020 in)
Limit 0.100 mm (0.0039 in)
Valve stem runout 0.010 mm (0.0004 in)

Cylinder head valve seat width (intake) 0.90–1.10 mm (0.0354–0.0433 in)

Limit 1.6 mm (0.06 in)
Cylinder head valve seat width (exhaust) 0.90–1.10 mm (0.0354–0.0433 in)
Limit 1.6 mm (0.06 in)

Valve spring
Inner spring
Free length (intake) 38.10 mm (1.50 in)
Limit 36.10 mm (1.42 in)
Free length (exhaust) 38.10 mm (1.50 in)
Limit 36.10 mm (1.42 in)
Installed length (intake) 30.10 mm (1.19 in)
Installed length (exhaust) 30.10 mm (1.19 in)
Spring rate K1 (intake) 10.29 N/mm (1.05 kgf/mm, 58.75 lb/in)
Spring rate K2 (intake) 13.37 N/mm (1.36 kgf/mm, 76.34 lb/in)
Spring rate K1 (exhaust) 10.29 N/mm (1.05 kgf/mm, 58.75 lb/in)
Spring rate K2 (exhaust) 13.37 N/mm (1.36 kgf/mm, 76.34 lb/in)
Installed compression spring force (intake) 76–88 N (7.75–8.97 kgf, 17.08–19.78 lbf)
Installed compression spring force (exhaust) 76–88 N (7.75–8.97 kgf, 17.08–19.78 lbf)
Spring tilt (intake) 2.5°/1.7 mm
Spring tilt (exhaust) 2.5°/1.7 mm

Winding direction (intake) Counterclockwise

Winding direction (exhaust) Counterclockwise
Outer spring
Free length (intake) 36.93 mm (1.45 in)
Limit 35.00 mm (1.38 in)
Free length (exhaust) 36.93 mm (1.45 in)
Limit 35.00 mm (1.38 in)
Installed length (intake) 31.60 mm (1.24 in)
Installed length (exhaust) 31.60 mm (1.24 in)

2-51
 ENGINE SPECIFICATIONS (YP250R)

Spring rate K1 (intake) 23.18 N/mm (2.36 kgf/mm, 132.36 lb/in)

Spring rate K2 (intake) 31.66 N/mm (3.23 kgf/mm, 180.78 lb/in)
Spring rate K1 (exhaust) 23.18 N/mm (2.36 kgf/mm, 132.36 lb/in)
Spring rate K2 (exhaust) 31.66 N/mm (3.23 kgf/mm, 180.78 lb/in)
Installed compression spring force (intake) 115–133 N (11.73–13.56 kgf, 25.85–29.90 lbf)
Installed compression spring force (exhaust) 115–133 N (11.73–13.56 kgf, 25.85–29.90 lbf)
Spring tilt (intake) 2.5°/1.6 mm
Spring tilt (exhaust) 2.5°/1.6 mm

Winding direction (intake) Clockwise

Winding direction (exhaust) Clockwise

Cylinder
Bore 69.000–69.005 mm (2.7165–2.7167 in)
Wear limit 69.100 mm (2.7205 in)
Taper limit 0.030 mm (0.0012 in)
Out of round limit 0.030 mm (0.0012 in)
Warp limit 0.05 mm (0.0020 in)

Piston
Piston-to-cylinder clearance 0.020–0.040 mm (0.0008–0.0016 in)
Limit 0.15 mm (0.0059 in)
Diameter D 68.965–68.980 mm (2.7152–2.7157 in)
Height H 5.0 mm (0.20 in)

H
D

Offset 0.50 mm (0.0197 in)

Offset direction Intake side
Piston pin bore inside diameter 17.004–17.015 mm (0.6694–0.6699 in)
Limit 17.045 mm (0.6711 in)
Piston pin outside diameter 16.991–17.000 mm (0.6689–0.6693 in)
Limit 16.971 mm (0.6681 in)
Piston-pin-to-piston-pin-bore clearance 0.004–0.024 mm (0.0002–0.0009 in)
Limit 0.074 mm (0.0029 in)

Piston ring
Top ring
Ring type Barrel

2-52
 ENGINE SPECIFICATIONS (YP250R)

Dimensions (B × T) 1.00 × 2.60 mm (0.04 × 0.10 in)

B
T

End gap (installed) 0.15–0.30 mm (0.0059–0.0118 in)

Limit 0.55 mm (0.0217 in)
Ring side clearance 0.040–0.080 mm (0.0016–0.0031 in)
Limit 0.130 mm (0.0051 in)
2nd ring
Ring type Taper
Dimensions (B × T) 1.00 × 2.90 mm (0.04 × 0.11 in)

B
T

End gap (installed) 0.30–0.45 mm (0.0118–0.0177 in)

Limit 0.80 mm (0.0315 in)
Ring side clearance 0.030–0.070 mm (0.0012–0.0028 in)
Limit 0.130 mm (0.0051 in)
Oil ring
Dimensions (B × T) 1.50 × 2.50 mm (0.06 × 0.10 in)

B
T

End gap (installed) 0.20–0.70 mm (0.0079–0.0276 in)

Ring side clearance 0.060–0.150 mm (0.0024–0.0059 in)

Crankshaft
Width A 59.75–59.80 mm (2.352–2.354 in)
Runout limit C 0.030 mm (0.0012 in)
Big end side clearance D 0.350–0.850 mm (0.0138–0.0335 in)
Big end radial clearance E 0.010–0.025 mm (0.0004–0.0010 in)

C C

E
D

Clutch
Clutch type Dry, centrifugal automatic

Automatic centrifugal clutch

Clutch shoe thickness 3.3 mm (0.13 in)
Limit 2.0 mm (0.08 in)

2-53
 ENGINE SPECIFICATIONS (YP250R)

Clutch shoe spring free length 40.5 mm (1.59 in)

Clutch housing inside diameter 145.0 mm (5.71 in)
Limit 145.5 mm (5.73 in)
Compression spring free length 102.4 mm (4.03 in)
Limit 90.0 mm (3.54 in)
Weight outside diameter 20.0 mm (0.79 in)
Limit 19.5 mm (0.77 in)
Clutch-in revolution 2100–2700 r/min
Clutch-stall revolution 3650–4650 r/min

V-belt
V-belt width 23.0 mm (0.91 in)
Limit 21.0 mm (0.83 in)

Transmission
Transmission type V-belt automatic
Primary reduction system Helical gear
Primary reduction ratio 40/15 (2.666)
Secondary reduction system Helical gear
Secondary reduction ratio 40/14 (2.857)
Operation Centrifugal automatic type
Gear ratio 2.440–0.830 :1

Air filter
Air filter element Oil-coated paper element

Fuel pump
Pump type Electrical
Output pressure 250.0 kPa (2.50 kgf/cm², 36.3 psi)

Fuel injector
Model/quantity 1C04/1

Throttle body
Type/quantity EFI 1C04/1
ID mark 1C04 00

Throttle position sensor

Input voltage (at idle) 5V
Output voltage (at idle) 0.40–0.90 V

Fuel injection sensor

Crankshaft position sensor resistance 248–372 Ω at 20 °C (68 °F)
Intake air pressure sensor output voltage 3.57–3.71 V
Intake air temperature sensor resistance 2.21–2.69 kΩ at 20 °C (68 °F)
Coolant temperature sensor resistance 2.32–2.59 kΩ at 20 °C (68 °F)
310–326 Ω at 80 °C (176 °F)

Idling condition
Engine idling speed 1450–1650 r/min
CO% (muffler tailpipe) 0.3–0.7%
Intake vacuum 39.0–45.0 kPa (293–338 mmHg, 11.5–13.3
inHg)

2-54
 ENGINE SPECIFICATIONS (YP250R)

Water temperature 85.0–95.0 °C (185.00–203.00 °F)

Oil temperature 75.0–85.0 °C (167.00–185.00 °F)
Throttle cable free play 3.0–5.0 mm (0.12–0.20 in)

2-55
 CHASSIS SPECIFICATIONS (YP250R)

EAS20300

CHASSIS SPECIFICATIONS (YP250R)

Chassis
Frame type Steel tube underbone
Caster angle 28.00°
Trail 100.0 mm (3.94 in)

Front wheel
Wheel type Cast wheel
Rim size 15 × MT3.5
Rim material Aluminum
Wheel travel 110.0 mm (4.33 in)
Radial wheel runout limit 1.0 mm (0.04 in)
Lateral wheel runout limit 0.5 mm (0.02 in)
Wheel axle bending limit 0.25 mm (0.01 in)

Rear wheel
Wheel type Cast wheel
Rim size 14 × MT3.75
Rim material Aluminum
Wheel travel 95.0 mm (3.74 in)
Radial wheel runout limit 1.0 mm (0.04 in)
Lateral wheel runout limit 0.5 mm (0.02 in)
Wheel axle bending limit 0.25 mm (0.01 in)

Front tire
Type Tubeless
Size 120/70–15 M/C 56P (PIRELLI)
120/70–15 M/C 56S (MICHELIN)
Manufacturer/model MICHELIN/GOLD STANDARD
PIRELLI/GTS23
Wear limit (front) 1.6 mm (0.06 in)

Rear tire
Type Tubeless
Size 140/70–14 M/C 68P (PIRELLI)
140/70–14 M/C 68S (MICHELIN)
Manufacturer/model MICHELIN/GOLD STANDARD
PIRELLI/GTS24
Wear limit (rear) 1.6 mm (0.06 in)

Tire air pressure (measured on cold tires)

Loading condition 0–90 kg (0–198 lb)
Front 190 kPa (1.90 kgf/cm², 28 psi)
Rear 220 kPa (2.20 kgf/cm², 32 psi)
Loading condition 90 kg–maximum load
Front 210 kPa (2.10 kgf/cm², 30 psi)
Rear 250 kPa (2.50 kgf/cm², 36 psi)

Front brake
Type Single disc brake
Operation Right hand operation

2-56
 CHASSIS SPECIFICATIONS (YP250R)

Front disc brake

Disc outside diameter × thickness 267.0 × 5.0 mm (10.51 × 0.20 in)
Brake disc thickness limit 4.5 mm (0.18 in)
Brake disc deflection limit 0.15 mm (0.0059 in)
Brake pad lining thickness (inner) 5.0 mm (0.20 in)
Limit 1.5 mm (0.06 in)
Brake pad lining thickness (outer) 5.0 mm (0.20 in)
Limit 1.5 mm (0.06 in)
Master cylinder inside diameter 12.70 mm (0.50 in)
Caliper cylinder inside diameter 27.00 mm × 2 (1.06 in × 2)
Recommended fluid DOT 4

Rear brake
Type Single disc brake
Operation Left hand operation
Rear disc brake
Disc outside diameter × thickness 240.0 × 5.0 mm (9.45 × 0.20 in)
Brake disc thickness limit 4.5 mm (0.18 in)
Brake disc deflection limit 0.15 mm (0.0059 in)
Brake pad lining thickness (inner) 5.3 mm (0.21 in)
Limit 0.8 mm (0.03 in)
Brake pad lining thickness (outer) 5.3 mm (0.21 in)
Limit 0.8 mm (0.03 in)
Master cylinder inside diameter 11.0 mm (0.43 in)
Caliper cylinder inside diameter 22.22 mm × 2 (0.87 in × 2)
Recommended fluid DOT 4

Steering
Steering bearing type Ball and angular bearings
Center to lock angle (left) 57.0°
Center to lock angle (right) 57.0°
No./size of steel balls
(Upper) 14 pcs
(Lower) 18 pcs

Front suspension
Type Telescopic fork
Spring/shock absorber type Coil spring/oil damper
Front fork travel 110.0 mm (4.33 in)
Fork spring free length 340.0 mm (13.39 in)
Limit 333.0 mm (13.11 in)
Installed length 285.1 mm (11.22 in)
Spring rate K1 12.00 N/mm (1.22 kgf/mm, 68.52 lb/in)
Spring rate K2 16.60 N/mm (1.69 kgf/mm, 94.79 lb/in)
Spring stroke K1 0–77.0 mm (0–3.03 in)
Spring stroke K2 77.0–110.0 mm (3.03–4.33 in)
Inner tube outer diameter 35.0 mm (1.38 in)
Inner tube bending limit 0.2 mm (0.01 in)
Optional spring available No
Recommended oil Fork oil 10W or equivalent
Quantity 128.0 cm³ (4.33 US oz, 4.51 Imp.oz)
Level 109.0 mm (4.29 in)

2-57
 CHASSIS SPECIFICATIONS (YP250R)

Rear suspension
Type Unit swing
Spring/shock absorber type Coil spring/oil damper
Rear shock absorber assembly travel 95.0 mm (3.74 in)
Spring free length 274.0 mm (10.79 in)
Installed length 241.3 mm (9.50 in)
Spring rate K1 8.00 N/mm (0.82 kgf/mm, 45.68 lb/in)
Spring rate K2 17.30 N/mm (1.76 kgf/mm, 98.78 lb/in)
Spring stroke K1 0–47.5 mm (0–1.87 in)
Spring stroke K2 47.5–95.0 mm (1.87–3.74 in)
Optional spring available No
Spring preload adjusting positions
Minimum 1
Standard 2
Maximum 4

Swingarm
Swingarm end free play limit (radial) 1.0 mm (0.04 in)
Swingarm end free play limit (axial) 1.0 mm (0.04 in)

2-58
 ELECTRICAL SPECIFICATIONS (YP250R)

EAS20310

ELECTRICAL SPECIFICATIONS (YP250R)

Voltage
System voltage 12 V

Ignition system
Ignition system TCI (digital)
Advancer type Digital
Ignition timing (B.T.D.C.) 10.0°/1550 r/min

Engine control unit

Model/manufacturer 37P0/YAMAHA

Ignition coil
Minimum ignition spark gap 6.0 mm (0.24 in)
Primary coil resistance 2.16–2.64 Ω at 20 °C (68 °F)
Secondary coil resistance 8.64–12.96 kΩ at 20 °C (68 °F)

Spark plug cap

Material Resin
Resistance 10.0 kΩ

AC magneto
Standard output 14.0 V, 260 W 5000 r/min
Stator coil resistance 0.32–0.48 Ω at 20 °C (68 °F)

Rectifier/regulator
Regulator type Semi conductor-short circuit
Regulated voltage (DC) 14.1–14.9 V
Rectifier capacity 25.0 A
Rectifier capacity (DC) 18.0 A
Withstand voltage 200.0 V

Battery
Model GTX9-BS
Voltage, capacity 12 V, 8.0 Ah
Manufacturer GS

Headlight
Bulb type Halogen bulb

Bulb voltage, wattage × quantity

Low beam headlight 12 V, 55.0 W × 1
High beam headlight 12 V, 55.0 W × 1
Auxiliary light 12 V, 5.0 W × 2
Tail/brake light 12 V, 5.0 W/21.0 W × 2
Front turn signal light 12 V, 10.0 W × 2
Rear turn signal light 12 V, 10.0 W × 2
License plate light 12 V, 5.0 W × 1
Meter lighting 12 V, 2.0 W × 3

2-59
 ELECTRICAL SPECIFICATIONS (YP250R)

Indicator lights
Turn signal indicator light 12 V, 1.4 W × 2
High beam indicator light 12 V, 1.4 W × 1
Engine trouble warning light 12 V, 1.4 W × 1
Immobilizer system indicator light LED

Electric starting system

System type Constant mesh

Starter motor
Power output 0.65 kW
Armature coil resistance 0.0100–0.0140 Ω
Brush overall length 9.0 mm (0.35 in)
Limit 3.00 mm (0.12 in)
Brush spring force 7.75 N (790 gf, 27.90 oz)
Commutator diameter 24.0 mm (0.94 in)
Limit 22.4 mm (0.88 in)
Mica undercut (depth) 1.00 mm (0.04 in)

Starter relay
Amperage 180.0 A

Horn
Horn type Plane
Quantity 1 pc
Maximum amperage 3.0 A
Coil resistance 1.4 Ω at 20 °C (68 °F)
Performance 105–118 dB/2m

Turn signal relay

Relay type Full transistor
Built-in, self-canceling device No
Turn signal flashing frequency 75–95 cycles/min
Wattage 21 W × 2.0 + 3.4 W

Fuel sender unit

Sender unit resistance (full) 20.0 Ω
Sender unit resistance (empty) 140.0 Ω

Starting circuit cut-off relay

Diode Yes

Fuses
Main fuse 30.0 A
Headlight fuse 15.0 A
Signaling system fuse 10.0 A
Ignition fuse 10.0 A
Radiator fan fuse 7.5 A
Turn signal/hazard fuse 10.0 A
ECU fuse 5.0 A
Backup fuse 5.0 A
Spare fuse 30.0 A

2-60
 ELECTRICAL SPECIFICATIONS (YP250R)

Spare fuse 15.0 A

Spare fuse 10.0 A
Spare fuse 5.0 A
Spare fuse 7.5 A

2-61
 TIGHTENING TORQUES (YP250R)

EAS20320

TIGHTENING TORQUES (YP250R)

EAS20330

GENERAL TIGHTENING TORQUE

SPECIFICATIONS
This chart specifies tightening torques for stan-
dard fasteners with a standard ISO thread pitch.
Tightening torque specifications for special com-
ponents or assemblies are provided for each
chapter of this manual. To avoid warpage, tight-
en multi-fastener assemblies in a crisscross pat-
tern and progressive stages until the specified
tightening torque is reached. Unless otherwise
specified, tightening torque specifications re-
quire clean, dry threads. Components should be
at room temperature.

A. Distance between flats

B. Outside thread diameter

General tightening
A (nut) B (bolt) torques
Nm m·kgf ft·lbf
10 mm 6 mm 6 0.6 4.3
12 mm 8 mm 15 1.5 11
14 mm 10 mm 30 3.0 22
17 mm 12 mm 55 5.5 40
19 mm 14 mm 85 8.5 61
22 mm 16 mm 130 13.0 94

2-62
 TIGHTENING TORQUES (YP250R)

EAS20340

ENGINE TIGHTENING TORQUES

Thread
Item Q’ty Tightening torque Remarks
size
Exhaust pipe nut M8 2 20 Nm (2.0 m·kgf, 14 ft·lbf)
Muffler bolt M10 3 53 Nm (5.3 m·kgf, 38 ft·lbf)
Muffler joint bolt M8 1 14 Nm (1.4 m·kgf, 10 ft·lbf)
O2 sensor M18 1 45 Nm (4.5 m·kgf, 32 ft·lbf)
Oil check bolt M6 1 7 Nm (0.7 m·kgf, 5.1 ft·lbf)
Tappet cover bolt M6 5 10 Nm (1.0 m·kgf, 7.2 ft·lbf)
Cylinder head nut M8 4 22 Nm (2.2 m·kgf, 16 ft·lbf)
Cylinder head bolt M6 2 10 Nm (1.0 m·kgf, 7.2 ft·lbf)
Cylinder head stud bolt M8 4 13 Nm (1.3 m·kgf, 9.4 ft·lbf)
Exhaust pipe stud bolt M8 2 13 Nm (1.3 m·kgf, 9.4 ft·lbf)
Timing chain tensioner bolt M6 2 10 Nm (1.0 m·kgf, 7.2 ft·lbf)
Timing chain tensioner cap bolt M8 1 8 Nm (0.8 m·kgf, 5.8 ft·lbf)
Spark plug M12 1 18 Nm (1.8 m·kgf, 13 ft·lbf)
Coolant temperature sensor M12 1 18 Nm (1.8 m·kgf, 13 ft·lbf)
Camshaft sprocket cover bolt M6 2 10 Nm (1.0 m·kgf, 7.2 ft·lbf)
Camshaft sprocket bolt M10 1 60 Nm (6.0 m·kgf, 43 ft·lbf)
Camshaft retainer bolt M6 2 8 Nm (0.8 m·kgf, 5.8 ft·lbf)
Valve clearance adjusting screw
M6 2 14 Nm (1.4 m·kgf, 10 ft·lbf)
locknut
V-belt case cover bolt M6 1 7 Nm (0.7 m·kgf, 5.1 ft·lbf)
V-belt case cover screw M6 3 7 Nm (0.7 m·kgf, 5.1 ft·lbf)
V-belt case bolt M6 11 10 Nm (1.0 m·kgf, 7.2 ft·lbf)
Primary sheave nut M14 1 80 Nm (8.0 m·kgf, 58 ft·lbf)
Secondary sheave nut M14 1 60 Nm (6.0 m·kgf, 43 ft·lbf)
Secondary sheave bracket bolt M8 4 22 Nm (2.2 m·kgf, 16 ft·lbf) LT

Primary sheave cap bolt M4 4 3 Nm (0.3 m·kgf, 2.2 ft·lbf)

Clutch carrier nut M36 1 90 Nm (9.0 m·kgf, 65 ft·lbf)
Timing mark accessing plug M16 1 8 Nm (0.8 m·kgf, 5.8 ft·lbf)
Generator cover bolt M6 10 10 Nm (1.0 m·kgf, 7.2 ft·lbf)
Stator coil bolt M6 3 10 Nm (1.0 m·kgf, 7.2 ft·lbf) LT

Crankshaft position sensor bolt M5 2 7 Nm (0.7 m·kgf, 5.1 ft·lbf) LT

Generator rotor nut M16 1 80 Nm (8.0 m·kgf, 58 ft·lbf)

Starter clutch bolt M8 3 30 Nm (3.0 m·kgf, 22 ft·lbf) LT

Starter motor bolt M6 2 7 Nm (0.7 m·kgf, 5.1 ft·lbf)

Starter motor bush holder set nut M6 1 7 Nm (0.7 m·kgf, 5.1 ft·lbf)
Starter motor front cover bolt M5 2 5 Nm (0.5 m·kgf, 3.6 ft·lbf)
Oil baffle plate bolt M6 2 12 Nm (1.2 m·kgf, 8.7 ft·lbf) LT

2-63
 TIGHTENING TORQUES (YP250R)

Thread
Item Q’ty Tightening torque Remarks
size
Oil pump assembly bolt M6 2 7 Nm (0.7 m·kgf, 5.1 ft·lbf)
Transmission case cover bolt M8 6 16 Nm (1.6 m·kgf, 11 ft·lbf)
Oil strainer cover M35 1 32 Nm (3.2 m·kgf, 23 ft·lbf)
Engine oil drain bolt M12 1 20 Nm (2.0 m·kgf, 14 ft·lbf)
Final transmission oil drain bolt M8 1 22 Nm (2.2 m·kgf, 16 ft·lbf)
Crankcase bolt M6 9 10 Nm (1.0 m·kgf, 7.2 ft·lbf)
Timing chain guide bolt (intake
M6 1 10 Nm (1.0 m·kgf, 7.2 ft·lbf)
side)
Air bleed bolt (thermostat cover) M4 1 3 Nm (0.3 m·kgf, 2.2 ft·lbf)
Thermostat cover bolt M6 2 10 Nm (1.0 m·kgf, 7.2 ft·lbf)
Water pump housing bolt M6 2 10 Nm (1.0 m·kgf, 7.2 ft·lbf)
Water pump housing cover bolt M6 2 10 Nm (1.0 m·kgf, 7.2 ft·lbf)
Coolant drain bolt (water pump) M6 1 10 Nm (1.0 m·kgf, 7.2 ft·lbf)
Water pump outlet pipe bolt M6 2 7 Nm (0.7 m·kgf, 5.1 ft·lbf)
Fuel injector assembly bolt M6 1 12 Nm (1.2 m·kgf, 8.7 ft·lbf)
Fuel injector assembly holder
M6 1 12 Nm (1.2 m·kgf, 8.7 ft·lbf)
bolt
Intake air pressure sensor bolt M6 2 10 Nm (1.0 m·kgf, 7.2 ft·lbf)
Intake air pressure sensor brack-
M6 1 10 Nm (1.0 m·kgf, 7.2 ft·lbf)
et bolt
Intake manifold bolt M6 2 10 Nm (1.0 m·kgf, 7.2 ft·lbf)
Throttle body clamp screw M4 1 3 Nm (0.3 m·kgf, 2.2 ft·lbf)
Throttle cable bracket bolt M5 2 5 Nm (0.5 m·kgf, 3.6 ft·lbf)
Air filter case mounting bolt M6 2 9 Nm (0.9 m·kgf, 6.5 ft·lbf) LT

2-64
 TIGHTENING TORQUES (YP250R)

Cylinder head tightening sequence:

Muffler tightening sequence:

2
3

2-65
 TIGHTENING TORQUES (YP250R)

EAS20350

CHASSIS TIGHTENING TORQUES

Thread
Item Q’ty Tightening torque Remarks
size
Engine bracket nut M12 2 59 Nm (5.9 m·kgf, 43 ft·lbf)
Engine bracket rod nut M10 2 64 Nm (6.4 m·kgf, 46 ft·lbf)
Engine mounting nut M10 1 43 Nm (4.3 m·kgf, 31 ft·lbf)
Radiator bolt M6 2 10 Nm (1.0 m·kgf, 7.2 ft·lbf)
Filler neck bolt M6 1 7 Nm (0.7 m·kgf, 5.1 ft·lbf)
Coolant reservoir bolt M6 2 7 Nm (0.7 m·kgf, 5.1 ft·lbf)
Radiator bracket nut M6 4 10 Nm (1.0 m·kgf, 7.2 ft·lbf)
Fuel tank bolt M6 3 14 Nm (1.4 m·kgf, 10 ft·lbf)
Fuel tank bracket bolt M6 4 13 Nm (1.3 m·kgf, 9.4 ft·lbf) LT

Seat nut M6 4 10 Nm (1.0 m·kgf, 7.2 ft·lbf)

Seat hinge and storage box nut M6 1 7 Nm (0.7 m·kgf, 5.1 ft·lbf)
Seat hinge spring guide bolt M6 2 10 Nm (1.0 m·kgf, 7.2 ft·lbf)
Storage box bolt M6 2 11 Nm (1.1 m·kgf, 8.0 ft·lbf)
Grab bar bolt M8 4 23 Nm (2.3 m·kgf, 17 ft·lbf) LT

Center panel bolt M6 6 10 Nm (1.0 m·kgf, 7.2 ft·lbf)

Rear panel bolt M6 2 10 Nm (1.0 m·kgf, 7.2 ft·lbf)
Mudguard bolt M6 3 11 Nm (1.1 m·kgf, 8.0 ft·lbf) LT

Rear fender bolt M6 1 7 Nm (0.7 m·kgf, 5.1 ft·lbf)

Front cowling assembly bolt M6 1 7 Nm (0.7 m·kgf, 5.1 ft·lbf)
Battery box bolt M6 1 11 Nm (1.1 m·kgf, 8.0 ft·lbf)
Battery holder bolt M6 1 7 Nm (0.7 m·kgf, 5.1 ft·lbf)
Battery bracket bolt M8 4 30 Nm (3.0 m·kgf, 22 ft·lbf)
Windshield bracket bolt M6 2 7 Nm (0.7 m·kgf, 5.1 ft·lbf)
Windshield bracket bolt M6 2 10 Nm (1.0 m·kgf, 7.2 ft·lbf) LT

Bottom cover bolt M6 2 11 Nm (1.1 m·kgf, 8.0 ft·lbf)

Storage compartment bolt M6 1 10 Nm (1.0 m·kgf, 7.2 ft·lbf)
Footrest board bolt M6 6 7 Nm (0.7 m·kgf, 5.1 ft·lbf)
Sidestand nut M10 1 56 Nm (5.6 m·kgf, 40 ft·lbf)
Sidestand switch nut M5 2 8 Nm (0.8 m·kgf, 5.8 ft·lbf)
Front fender bolt M6 4 7 Nm (0.7 m·kgf, 5.1 ft·lbf) LT

Front wheel axle M14 1 70 Nm (7.0 m·kgf, 50 ft·lbf)

Front wheel axle pinch bolt M8 1 23 Nm (2.3 m·kgf, 17 ft·lbf)
Front brake disc bolt M6 5 12 Nm (1.2 m·kgf, 8.7 ft·lbf) LT

Rear wheel axle nut M14 1 135 Nm (13.5 m·kgf, 98 ft·lbf)

Rear brake disc bolt M8 4 23 Nm (2.3 m·kgf, 17 ft·lbf) LT

Front brake caliper bolt M8 2 40 Nm (4.0 m·kgf, 29 ft·lbf)

Front brake hose union bolt M10 2 23 Nm (2.3 m·kgf, 17 ft·lbf)

2-66
 TIGHTENING TORQUES (YP250R)

Thread
Item Q’ty Tightening torque Remarks
size
Front brake hose holder bolt M6 1 7 Nm (0.7 m·kgf, 5.1 ft·lbf)
Front brake caliper bleed screw M7 1 6 Nm (0.6 m·kgf, 4.3 ft·lbf)
Front brake pad pin cap M8 1 3 Nm (0.3 m·kgf, 2.2 ft·lbf)
Front brake pad pin M8 1 18 Nm (1.8 m·kgf, 13 ft·lbf)
Front brake caliper retaining pin M8 1 23 Nm (2.3 m·kgf, 17 ft·lbf) LT

Front brake caliper retaining pin M8 1 13 Nm (1.3 m·kgf, 9.4 ft·lbf) LT

Rear brake caliper bolt M10 3 40 Nm (4.0 m·kgf, 29 ft·lbf)

Rear brake hose union bolt M10 2 23 Nm (2.3 m·kgf, 17 ft·lbf)
Rear brake hose holder bolt M6 1 7 Nm (0.7 m·kgf, 5.1 ft·lbf)
Rear brake caliper bleed screw M7 1 6 Nm (0.6 m·kgf, 4.3 ft·lbf)
Rear brake caliper retaining bolt M10 2 27 Nm (2.7 m·kgf, 19 ft·lbf)
Upper handlebar holder bolt M8 4 23 Nm (2.3 m·kgf, 17 ft·lbf)
Front and rear brake master cyl-
M6 4 7 Nm (0.7 m·kgf, 5.1 ft·lbf)
inder holder bolt
Front and rear brake lever nut M6 2 10 Nm (1.0 m·kgf, 7.2 ft·lbf)
Grip end M16 2 26 Nm (2.6 m·kgf, 19 ft·lbf)
Steering stem nut M20 1 120 Nm (12 m·kgf, 85 ft·lbf)
Upper ring nut M25 1 75 Nm (7.5 m·kgf, 54 ft·lbf) See TIP.
Lower ring nut (initial tightening
M25 1 38 Nm (3.8 m·kgf, 27 ft·lbf) See TIP.
torque)
Lower ring nut (final tightening
M25 1 22 Nm (2.2 m·kgf, 16 ft·lbf) See TIP.
torque)
Speed sensor lead holder brack-
M6 1 9 Nm (0.9 m·kgf, 6.5 ft·lbf)
et bolt
Lower bracket pinch bolt M8 4 23 Nm (2.3 m·kgf, 17 ft·lbf)
Cap bolt M29 2 45 Nm (4.5 m·kgf, 32 ft·lbf)
Damper rod bolt M10 2 30 Nm (3.0 m·kgf, 22 ft·lbf) LT

See TIP.
Swingarm bolt M10 2 59 Nm (5.9 m·kgf, 43 ft·lbf)
LT

Rear shock absorber assembly

M10 2 32 Nm (3.2 m·kgf, 23 ft·lbf)
nut (upper side)
Rear shock absorber assembly
M8 2 18 Nm (1.8 m·kgf, 13 ft·lbf)
bolt (lower side)
Ignition coil bolt M6 2 10 Nm (1.0 m·kgf, 7.2 ft·lbf)
ECU (engine control unit) bolt M6 2 7 Nm (0.7 m·kgf, 5.1 ft·lbf)
Rectifier/regulator bolt M6 2 7 Nm (0.7 m·kgf, 5.1 ft·lbf)
Battery terminal bolt M6 2 7 Nm (0.7 m·kgf, 5.1 ft·lbf)
Horn bolt M6 1 7 Nm (0.7 m·kgf, 5.1 ft·lbf)

2-67
 TIGHTENING TORQUES (YP250R)

TIP
Lower ring nut
1. Tighten the lower ring nut 38 Nm (3.8 m·kgf, 27 ft·lbf) with a torque wrench and the steering nut
wrench, and then loosen the nut 1/4 turn.
2. Tighten the lower ring nut 22 Nm (2.2 m·kgf, 16 ft·lbf) with a torque wrench and the steering nut
wrench.
3. Install the rubber washer and the center ring nut.
4. Finger tighten the center ring nut, align the slots of both ring nuts, and then install the lock washer.
5. Hold the lower and center ring nuts, and then tighten the upper ring nut 75 Nm (7.5 m·kgf, 54 ft·lbf)
with a torque wrench and the steering nut wrench.
TIP
Swingarm mounting bolt
1. Temporarily install the rear wheel axle nut “1”.
2. Temporarily install the swingarm mounting bolt (upper side) “2”, then the swingarm mounting bolt
(lower side) “3”.
3. Tighten the rear wheel axle nut to 135 Nm (13.5 m·kgf, 98 ft·lbf).
4. Tighten the swingarm mounting bolt (upper side), then the swingarm mounting bolt (lower side) to
59 Nm (5.9 m·kgf, 43 ft·lbf).

Swingarm tightening sequence:

1
3

2-68
 LUBRICATION POINTS AND LUBRICANT TYPES (YP250R)

EAS20360

LUBRICATION POINTS AND LUBRICANT TYPES (YP250R)

EAS20370

ENGINE
Lubrication point Lubricant
Oil seal lips LS

O-rings LS

Bearings E

Cylinder head nut mounting surface E

Crankshaft pin E

Connecting rod big end thrust surface E

Rotary filter inner surface E

Oil pump drive gear inner surface E

Camshaft sprocket inner surface E

Piston pin and connecting rod small end E

Piston, piston rings, and cylinder inner surface E

Camshaft lobes M

Valve stems (intake and exhaust) M

Valve stem ends (intake and exhaust) M

Rocker arm shafts E

Rocker arm inner surface M

Impeller shaft gear M

Oil pump shaft M

Oil pump rotors (inner and outer) E

Oil pump gasket LS

Engine mounting collars LS

Starter clutch idle gear thrust surface E

Starter clutch idle gear shaft E

Starter clutch gear thrust surface E

Starter clutch gear inner surface E

Main axle thrust surfaces E

Main axle serration E

Drive axle serration E

BEL-RAY assembly
Oil seal (secondary sliding sheave)
lube®
BEL-RAY assembly
O-ring and collar (clutch housing)
lube®
Yamaha bond
Crankcase mating surfaces
No.1215

2-69
 LUBRICATION POINTS AND LUBRICANT TYPES (YP250R)

Lubrication point Lubricant

Yamaha bond No.
Crankshaft position sensor/stator assembly lead grommet
1215

2-70
 LUBRICATION POINTS AND LUBRICANT TYPES (YP250R)

EAS20380

CHASSIS
Lubrication point Lubricant
Drive axle LS

Swingarm oil seal lips LS

Steering bearings (upper and lower) LS

Seat hinge pin LS

Front wheel oil seal lip and front wheel axle LS

Speed sensor oil seal lip LS

Brake lever pivoting point and metal-to-metal moving parts S

Rear brake caliper retaining bolt S

Throttle cable end LS

Throttle grip inner surface and throttle cables LS

Handlebar grip inner surface Rubber adhesive

Sidestand pivoting point and metal-to-metal moving parts LS

Sidestand spring hook metal-to-metal moving parts LS

Centerstand shaft pivoting point and metal-to-metal moving parts LS

Centerstand spring hook metal-to-metal moving parts LS

Passenger footrest pivoting point LS

2-71
LUBRICATION POINTS AND LUBRICANT TYPES (YP250R)

2-72
 COOLING SYSTEM DIAGRAMS (YP250R)

EAS20420

COOLING SYSTEM DIAGRAMS (YP250R)

3
A

2 A

6 7
2

2-73
 COOLING SYSTEM DIAGRAMS (YP250R)

1. Coolant reservoir
2. Coolant reservoir hose
3. Radiator cap
4. Radiator filler hose
5. Radiator
6. Radiator inlet hose
7. Radiator outlet hose

2-74
 CABLE ROUTING (YP250R)

EAS20430

CABLE ROUTING (YP250R)

Battery (front view)

15 3

A 1

2 B

3 C
15
4

14 6

7
E 13
8 D
12
9

10

11 17 2
16

13
G
9
10
11
H

2-75
 CABLE ROUTING (YP250R)

1. Positive battery lead

2. Meter assembly lead
3. Self-diagnosis signal lead
4. Fuse box 1
5. Air temperature sensor lead
6. Fuse box 2
7. Starter relay lead
8. Negative battery lead
9. Headlight lead
10. Wire harness
11. Lean angle sensor lead
12. Speed sensor coupler
13. Turn signal/hazard relay lead
14. Turn signal/hazard relay
15. Battery
16. Fuse box 2 lead
17. Fuse box 1 lead
A. Route the positive battery lead under the battery
cover.
B. Route the meter assembly lead to the front of the
starter relay.
C. Route the self-diagnosis signal lead along the
negative battery lead.
D. Route the negative battery lead to the rear of the
turn signal/hazard relay lead, lean angle sensor
lead, and headlight lead.
E. Route the turn signal/hazard relay lead to the rear
of the lean angle sensor.
F. Point the end of the plastic locking tie forward, and
then cut off the excess end of the tie to 0–5 mm
(0–0.20 in).
G. Point the end of the plastic locking tie upward, and
then cut off the excess end of the tie to 0–5 mm
(0–0.20 in).
H. Fasten the wire harness and the other leads with a
plastic locking tie, making sure to align the tie with
the white tape on the harness.

2-76
 CABLE ROUTING (YP250R)

Front fork (front view)

2
1
1 2

1 2
A

7
4

6
5

2-77
 CABLE ROUTING (YP250R)

1. Speed sensor lead

2. Front brake hose
3. Rectifier/regulator
4. Left front turn signal light coupler
5. Wire harness
6. Horn
7. Right front turn signal light coupler
A. Point the end of the plastic locking tie forward, and
then cut off the excess end of the tie to 0–5 mm
(0–0.20 in).

2-78
 CABLE ROUTING (YP250R)

Front brake hose (right side view)

8
1
1

13

15 14

13
11 8

2
12 3
11
4
11 A 5

10

7 6

11
B 8 8
8

7 8

2-79
 CABLE ROUTING (YP250R)

1. Front brake hose

2. Radiator fan motor relay
3. Starting circuit cut-off relay
4. Speed sensor lead
5. Right front turn signal light
6. Radiator fan motor
7. Radiator fan motor lead
8. Wire harness
9. Rear brake pipe
10. Horn leads
11. Starter motor lead
12. Headlight relay
13. Rear brake hose
14. Throttle cables
15. Main switch/immobilizer unit lead
A. Position the plastic locking tie above the frame
cross member.
B. Point the end of the plastic locking tie to the right,
and then cut off the excess end of the tie to 0–5
mm (0–0.20 in).

2-80
 CABLE ROUTING (YP250R)

Engine (right side view)

B 7
2

1 2 3

7 6 3
5 4
8

2-81
 CABLE ROUTING (YP250R)

1. Seat lock cable

2. Wire harness
3. Ignition coil lead
4. Spark plug cap
5. Coolant temperature sensor lead
6. O2 sensor
7. Starter motor lead
8. Rear brake hose
A. Fasten the wire harness, starter motor lead,
crankshaft position sensor/stator assembly lead,
and O2 sensor lead with a plastic locking tie.
B. Point the end of the plastic locking tie to the right,
and then cut off the excess end of the tie to 0–5
mm (0–0.20 in).

2-82
 CABLE ROUTING (YP250R)

Throttle cables (left side view)

14
2

15
6 14 3 D
16 E D
13 17 17
11 12 4

5
6 F

6 6
6

I 7
A 8
B

10

7
H
3

G
3 H 5
5

2-83
 CABLE ROUTING (YP250R)

1. Meter assembly
2. ECU (engine control unit)
3. Seat lock cable
4. Immobilizer unit coupler
5. Throttle cables
6. Wire harness
7. Sidestand switch lead
8. Rear brake hose
9. Front brake hose
10. Left front turn signal light lead
11. Rectifier/regulator
12. Starter motor lead
13. Headlight coupler
14. Air temperature sensor lead
15. Immobilizer unit lead
16. Main switch lead
17. Connector cover
A. Route the sidestand switch lead to the outside of
the rear brake pipe.
B. Route the sidestand switch lead to the inside of the
frame.
C. Route the sidestand switch lead to the outside of
the frame.
D. Position the connector cover as shown in the
illustration.
E. Forward
F. Fasten the wire harness at the white tape with the
holder.
G. Point the end of the plastic locking tie to the right,
and then cut off the excess end of the tie to 0–5
mm (0–0.20 in).
H. Point the end of the plastic locking tie forward.
I. Point the end of the plastic locking tie to the left,
and then cut off the excess end of the tie to 0–5
mm (0–0.20 in).
J. Install the air temperature sensor so that there is
some slack in the air temperature sensor lead.

2-84
 CABLE ROUTING (YP250R)

Engine (left side view)

4
3
5

2
1
A

7 6

2-85
 CABLE ROUTING (YP250R)

1. Wire harness
2. Intake air temperature sensor
3. Seat lock cable
4. Left tail/brake light assembly
5. Safety protector
6. O2 sensor
7. Spark plug cap
A. Route the left tail/brake light assembly lead and
right tail/brake light assembly lead over the safety
protector.
B. Point the end of the plastic locking tie to the left,
and then cut off the excess end of the tie to 0–5
mm (0–0.20 in).

2-86
 CABLE ROUTING (YP250R)

Handlebar (top view)

1 2 3 4 5

17 6

16
7

8
15

14

13

12

11 10 9

2-87
 CABLE ROUTING (YP250R)

1. Radiator fan motor relay

2. Starting circuit cut-off relay
3. Headlight relay
4. Right handlebar switch lead
5. Front brake hose
6. Fuel pump coupler
7. Fuel sender coupler
8. Fuel hose
9. Left handlebar switch lead
10. Rear brake hose
11. ECU (engine control unit)
12. Positive battery lead
13. Negative battery lead
14. Fuse box 1
15. Fuse box 2
16. Battery
17. Turn signal/hazard relay
A. Point the end of the plastic locking tie to the left,
and then cut off the excess end of the tie to 0–5
mm (0–0.20 in).

2-88
 CABLE ROUTING (YP250R)

Throttle body (top view)

C 4 4 4 12

3 12
4
13 3 12

1 2 3

4
11

5
10

6 A

9 B
8 7

10 11 8

2-89
 CABLE ROUTING (YP250R)

1. Rear brake pipe

2. Intake air pressure sensor coupler
3. Wire harness
4. Starter motor lead
5. Ground lead
6. Breather hose (air filter case to throttle body)
7. Intake air temperature sensor coupler
8. Fuel injector lead
9. Seat lock cable
10. Cylinder head breather hose
11. Intake air pressure sensor hose
12. Crankshaft position sensor/stator assembly lead
13. O2 sensor lead
A. Connect the breather hose (air filter case to throttle
body) to the air filter case, making sure to turn the
white paint marks on the hose upward.
B. Route the seat lock cable to the inside of the
frame.
C. Point the end of the plastic locking tie to the right,
and then cut off the excess end of the tie to 0–5
mm (0–0.20 in).
D. Fasten the fuel injector lead at the white tape with
a plastic locking tie. Point the end of the plastic
locking tie upward, and then cut off the excess end
of the tie to 0–5 mm (0–0.20 in).

2-90
 CABLE ROUTING (YP250R)

Tail/brake light (top view)

1 A

1 2

3
4

8 7 6

2-91
 CABLE ROUTING (YP250R)

1. Wire harness
2. Rear brake hose
3. License plate light lead
4. Right tail/brake light assembly coupler
5. Left tail/brake light assembly coupler
6. Seat lock cable
7. Cylinder head breather hose
8. Intake air temperature sensor coupler
A. Point the end of the plastic locking tie to the right,
and then cut off the excess end of the tie to 0–5
mm (0–0.20 in).
B. Route the license plate light lead between the
water guard and the license plate light bracket.

2-92
 CABLE ROUTING (YP250R)

2-93
 PERIODIC CHECKS AND ADJUSTMENTS

PERIODIC MAINTENANCE ............................................................................ 3-1

INTRODUCTION ....................................................................................... 3-1
PERIODIC MAINTENANCE CHART FOR THE EMISSION CONTROL
SYSTEM (YP125R) .................................................................................. 3-1
GENERAL MAINTENANCE AND LUBRICATION CHART (YP125R) ...... 3-1
PERIODIC MAINTENANCE CHART FOR THE EMISSION CONTROL
SYSTEM (YP250R) .................................................................................. 3-3
GENERAL MAINTENANCE AND LUBRICATION CHART (YP250R) ...... 3-3

ENGINE (YP125R)........................................................................................... 3-6

ADJUSTING THE VALVE CLEARANCE .................................................. 3-6
ADJUSTING THE EXHAUST GAS VOLUME ........................................... 3-8
ADJUSTING THE THROTTLE CABLE FREE PLAY ................................ 3-9
CHECKING THE SPARK PLUG ............................................................... 3-9
CHECKING THE IGNITION TIMING....................................................... 3-10 3
MEASURING THE COMPRESSION PRESSURE.................................. 3-11
CHECKING THE ENGINE OIL LEVEL.................................................... 3-12
CHANGING THE ENGINE OIL ............................................................... 3-12
CHANGING THE FINAL TRANSMISSION OIL....................................... 3-14
REPLACING THE AIR FILTER ELEMENT ............................................. 3-15
CLEANING THE V-BELT CASE AIR FILTER ELEMENT ....................... 3-15
CHECKING THE THROTTLE BODY JOINT........................................... 3-16
CHECKING THE FUEL HOSE ................................................................ 3-16
CHECKING THE BREATHER HOSES ................................................... 3-16
CHECKING THE EXHAUST SYSTEM.................................................... 3-17
CHECKING THE COOLANT LEVEL....................................................... 3-17
CHECKING THE COOLING SYSTEM .................................................... 3-18
CHANGING THE COOLANT................................................................... 3-18

ENGINE (YP250R)......................................................................................... 3-21

ADJUSTING THE VALVE CLEARANCE ................................................ 3-21
ADJUSTING THE EXHAUST GAS VOLUME ......................................... 3-23
ADJUSTING THE THROTTLE CABLE FREE PLAY .............................. 3-23
CHECKING THE SPARK PLUG ............................................................. 3-24
CHECKING THE IGNITION TIMING....................................................... 3-25
MEASURING THE COMPRESSION PRESSURE.................................. 3-25
CHECKING THE ENGINE OIL LEVEL.................................................... 3-26
CHANGING THE ENGINE OIL ............................................................... 3-27
CHANGING THE FINAL TRANSMISSION OIL....................................... 3-28
REPLACING THE AIR FILTER ELEMENT ............................................. 3-29
CLEANING THE V-BELT CASE AIR FILTER ELEMENT ....................... 3-30
CHECKING THE THROTTLE BODY JOINT........................................... 3-30
CHECKING THE FUEL HOSE ................................................................ 3-30
CHECKING THE BREATHER HOSES ................................................... 3-30
CHECKING THE EXHAUST SYSTEM.................................................... 3-31
CHECKING THE COOLANT LEVEL....................................................... 3-31
CHECKING THE COOLING SYSTEM .................................................... 3-32
CHANGING THE COOLANT................................................................... 3-32
CHASSIS ....................................................................................................... 3-35
CHECKING THE BRAKE FLUID LEVEL................................................. 3-35
CHECKING THE FRONT BRAKE PADS ................................................ 3-35
CHECKING THE REAR BRAKE PADS (YP125R).................................. 3-35
CHECKING THE REAR BRAKE PADS (YP250R).................................. 3-36
CHECKING THE FRONT BRAKE HOSE................................................ 3-36
CHECKING THE REAR BRAKE HOSE .................................................. 3-36
BLEEDING THE HYDRAULIC BRAKE SYSTEM ................................... 3-36
CHECKING AND ADJUSTING THE STEERING HEAD ......................... 3-37
CHECKING THE FRONT FORK ............................................................. 3-39
ADJUSTING THE REAR SHOCK ABSORBER ASSEMBLIES .............. 3-39
CHECKING THE TIRES.......................................................................... 3-39
CHECKING THE WHEELS ..................................................................... 3-41
CHECKING AND LUBRICATING THE CABLES .................................... 3-41
LUBRICATING THE LEVERS ................................................................. 3-41
LUBRICATING THE SIDESTAND........................................................... 3-41
LUBRICATING THE CENTERSTAND .................................................... 3-42

ELECTRICAL SYSTEM................................................................................. 3-43

CHECKING AND CHARGING THE BATTERY....................................... 3-43
CHECKING THE FUSES ........................................................................ 3-43
REPLACING A HEADLIGHT BULB ........................................................ 3-43
ADJUSTING THE HEADLIGHT BEAM ................................................... 3-44
 PERIODIC MAINTENANCE

EAS20450

PERIODIC MAINTENANCE
EAS20460

INTRODUCTION
This chapter includes all information necessary to perform recommended checks and adjustments. If
followed, these preventive maintenance procedures will ensure more reliable vehicle operation, a long-
er service life and reduce the need for costly overhaul work. This information applies to vehicles already
in service as well as to new vehicles that are being prepared for sale. All service technicians should be
familiar with this entire chapter.
EAS37P1069

PERIODIC MAINTENANCE CHART FOR THE EMISSION CONTROL SYSTEM (YP125R)

TIP
• The annual checks must be performed every year, except if a kilometer-based maintenance,
or for the UK, a mileage-based maintenance, is performed instead.
• From 30000 km (17500 mi), repeat the maintenance intervals starting from 6000 km (3500 mi).
• Items marked with an asterisk should be performed by a Yamaha dealer as they require special tools,
data and technical skills.

ODOMETER READING
CHECK OR MAINTENANCE ANNUAL
NO. ITEM JOB CHECK
1000 km 6000 km 12000 km 18000 km 24000 km
(600 mi) (3500 mi) (7000 mi) (10500 mi) (14000 mi)

• Check fuel hoses for cracks or

1 * Fuel line damage. √ √ √ √ √

• Check condition. √ √
2 Spark plug • Clean and regap.
• Replace. √ √

3 * Valves • Check valve clearance. √ √ √ √

• Adjust.
4 * Fuel injection • Check engine idle speed. √ √ √ √ √ √

5 * Muffler and ex- • Check the screw clamp(s) for √ √ √ √ √

haust pipe looseness.

EAS37P1086

GENERAL MAINTENANCE AND LUBRICATION CHART (YP125R)

TIP
• The annual checks must be performed every year, except if a kilometer-based maintenance,
or for the UK, a mileage-based maintenance is performed instead.
• From 30000 km (17500 mi), repeat the maintenance intervals starting from 6000 km (3500 mi).
• Items marked with an asterisk should be performed by a Yamaha dealer as they require special tools,
data and technical skills.

ODOMETER READING
CHECK OR MAINTENANCE ANNUAL
NO. ITEM JOB CHECK
1000 km 6000 km 12000 km 18000 km 24000 km
(600 mi) (3500 mi) (7000 mi) (10500 mi) (14000 mi)

1 Air filter element • Replace. √ √

V-belt case air fil-
2 • Clean. √ √ √ √
ter element
• Check operation, fluid level
and vehicle for fluid leakage. √ √ √ √ √ √
3 * Front brake
• Replace brake pads. Whenever worn to the limit
• Check operation, fluid level
and vehicle for fluid leakage. √ √ √ √ √ √
4 * Rear brake
• Replace brake pads. Whenever worn to the limit

3-1
 PERIODIC MAINTENANCE

ODOMETER READING
CHECK OR MAINTENANCE ANNUAL
NO. ITEM
JOB 1000 km 6000 km 12000 km 18000 km 24000 km CHECK
(600 mi) (3500 mi) (7000 mi) (10500 mi) (14000 mi)

• Check for cracks or damage. √ √ √ √ √

5 * Brake hoses
• Replace. Every 4 years
6 * Wheels • Check runout and for damage. √ √ √ √
• Check tread depth and for
damage.
7 * Tires • Replace if necessary. √ √ √ √ √
• Check air pressure.
• Correct if necessary.
• Check bearing for looseness
8 * Wheel bearings √ √ √ √
or damage.
• Check bearing play and steer-
ing for roughness. √ √ √ √ √
9 * Steering bearings
• Lubricate with lithium-soap- Every 24000 km (14000 mi)
based grease.
• Make sure that all nuts, bolts
10 * Chassis fasteners and screws are properly tight- √ √ √ √ √
ened.
Front brake lever
11 • Lubricate with silicone grease. √ √ √ √ √
pivot shaft
Rear brake lever
12 pivot shaft • Lubricate with silicone grease. √ √ √ √ √

13 Sidestand, center- • Check operation. √ √ √ √ √

stand • Lubricate.
14 * Sidestand switch • Check operation. √ √ √ √ √ √

15 * Front fork • Check operation and for oil √ √ √ √

leakage.
Shock absorber • Check operation and shock
16 * √ √ √ √
assemblies absorbers for oil leakage.
When the oil change indicator flashes [5000 km (3000 mi)
• Change. √ after the initial 1000 km (600 mi) and every 6000 km (3500
17 Engine oil mi) thereafter]
• Check oil level and vehicle for
oil leakage. Every 3000 km (1800 mi) √

18 Engine oil filter el- • Replace. √ √ √

ement
• Check coolant level and vehi-
√ √ √ √ √
19 * Cooling system cle for coolant leakage.
• Change. Every 3 years

Final transmis- • Check vehicle for oil leakage. √ √ √

20
sion oil • Change. √ √ √
When the V-belt replacement indicator flashes [every 18000 km (10500
21 * V-belt • Replace. mi)]

22 * Front and rear • Check operation. √ √ √ √ √ √

brake switches
Moving parts and
23 • Lubricate. √ √ √ √ √
cables
• Check operation and free play.
Throttle grip • Adjust the throttle cable free
24 * housing and ca- play if necessary. √ √ √ √ √
ble • Lubricate the throttle grip
housing and cable.

25 * Lights, signals • Check operation. √ √ √ √ √ √

and switches • Adjust headlight beam.

3-2
 PERIODIC MAINTENANCE

EAS37P1070

TIP
• Engine air filter and V-belt air filter
• This model’s engine air filter is equipped with a disposable oil-coated paper element, which must not
be cleaned with compressed air to avoid damaging it.
• The engine air filter element needs to be replaced and the V-belt air filter element needs to be ser-
viced more frequently when riding in unusually wet or dusty areas.
• Hydraulic brake service
• After disassembling the brake master cylinders and calipers, always change the fluid. Regularly
check the brake fluid levels and fill the reservoirs as required.
• Every two years replace the internal components of the brake master cylinders and calipers, and
change the brake fluid.
• Replace the brake hoses every four years and if cracked or damaged.

EAU46910

PERIODIC MAINTENANCE CHART FOR THE EMISSION CONTROL SYSTEM (YP250R)

TIP
• The annual checks must be performed every year, except if a kilometer-based maintenance,
or for the UK, a milage-based maintenance, is performed instead.
• From 50000 km (30000 mi), repeat the maintenance intervals starting from 10000 km (6000 mi).
• Items marked with an asterisk should be performed by a Yamaha dealer as they require special tools,
data and technical skills.

ODOMETER READING
CHECK OR MAINTENANCE ANNUAL
NO. ITEM JOB CHECK
1000 km 10000 km 20000 km 30000 km 40000 km
(600 mi) (6000 mi) (12000 mi) (18000 mi) (24000 mi)

• Check fuel hoses for cracks or

1 * Fuel line damage. √ √ √ √ √

• Check condition. √ √
2 Spark plug • Clean and regap.
• Replace. √ √

3 * Valves • Check valve clearance. √ √

• Adjust.
4 * Fuel injection • Check engine idle speed. √ √ √ √ √ √

5 * Muffler and ex- • Check the screw clamp(s) for √ √ √ √ √

haust pipe looseness.

EAU1770C

GENERAL MAINTENANCE AND LUBRICATION CHART (YP250R)

TIP
• The annual checks must be performed every year, except if a kilometer-based maintenance,
or for the UK, a milage-based maintenance is performed instead.
• From 50000 km (30000 mi), repeat the maintenance intervals starting from 10000 km (6000 mi).
• Items marked with an asterisk should be performed by a Yamaha dealer as they require special tools,
data and technical skills.

ODOMETER READING
CHECK OR MAINTENANCE ANNUAL
NO. ITEM JOB CHECK
1000 km 10000 km 20000 km 30000 km 40000 km
(600 mi) (6000 mi) (12000 mi) (18000 mi) (24000 mi)

1 Air filter element • Replace. √ √

V-belt case air fil-
2 • Clean. √ √ √ √
ter element

3-3
 PERIODIC MAINTENANCE

ODOMETER READING
CHECK OR MAINTENANCE ANNUAL
NO. ITEM
JOB 1000 km 10000 km 20000 km 30000 km 40000 km CHECK
(600 mi) (6000 mi) (12000 mi) (18000 mi) (24000 mi)

• Check operation, fluid level

√ √ √ √ √ √
3 * Front brake and vehicle for fluid leakage.
• Replace brake pads. Whenever worn to the limit
• Check operation, fluid level √ √ √ √ √ √
4 * Rear brake and vehicle for fluid leakage.
• Replace brake pads. Whenever worn to the limit
• Check for cracks or damage. √ √ √ √ √
5 * Brake hoses
• Replace. Every 4 years
6 * Wheels • Check runout and for damage. √ √ √ √
• Check tread depth and for
damage.
7 * Tires • Replace if necessary. √ √ √ √ √
• Check air pressure.
• Correct if necessary.
• Check bearing for looseness
8 * Wheel bearings √ √ √ √
or damage.
• Check bearing play and steer-
ing for roughness. √ √ √ √ √
9 * Steering bearings
• Lubricate with lithium-soap- Every 20000 km (12000 mi)
based grease.
• Make sure that all nuts, bolts
10 * Chassis fasteners and screws are properly tight- √ √ √ √ √
ened.
Front brake lever
11 • Lubricate with silicone grease. √ √ √ √ √
pivot shaft
Rear brake lever
12 pivot shaft • Lubricate with silicone grease. √ √ √ √ √

13 Sidestand, center- • Check operation. √ √ √ √ √

stand • Lubricate.
14 * Sidestand switch • Check operation. √ √ √ √ √ √

15 * Front fork • Check operation and for oil √ √ √ √

leakage.
Shock absorber • Check operation and shock
16 * √ √ √ √
assemblies absorbers for oil leakage.
When the oil change indicator flashes [At 4000 km (2500
• Change. √ mi) and every 3000 km (1800 mi) thereafter]
17 Engine oil
• Check oil level and vehicle for Every 3000 km (1800 mi) √
oil leakage.
Engine oil strain-
18 * • Clean. √
er
• Check coolant level and vehi-
cle for coolant leakage. √ √ √ √ √
19 * Cooling system
• Change. Every 3 years

Final transmis- • Check vehicle for oil leakage. √ √ √

20 sion oil • Change. √ √ √
21 * V-belt • Replace. When V-belt replacement indicator flashes [Every 20000 km (12000 mi)]
Front and rear
22 * brake switches • Check operation. √ √ √ √ √ √

23 Moving parts and • Lubricate. √ √ √ √ √

cables
• Check operation and free play.
Throttle grip • Adjust the throttle cable free
24 * housing and ca- play if necessary. √ √ √ √ √
ble • Lubricate the throttle grip
housing and cable.
Lights, signals • Check operation.
25 * √ √ √ √ √ √
and switches • Adjust headlight beam.

3-4
 PERIODIC MAINTENANCE

EAU38262

TIP
• Engine air filter and V-belt air filters
• This model’s engine air filter is equipped with a disposable oil-coated paper element, which must not
be cleaned with compressed air to avoid damaging it.
• The engine air filter element needs to be replaced and the V-belt air filter element needs to be ser-
viced more frequently when riding in unusually wet or dusty areas.
• Hydraulic brake service
• After disassembling the brake master cylinders and calipers, always change the fluid. Regularly
check the brake fluid levels and fill the reservoirs as required.
• Every two years replace the internal components of the brake master cylinders and calipers, and
change the brake fluid.
• Replace the brake hoses every four years and if cracked or damaged.

3-5
 ENGINE (YP125R)

EAS37P1087

ENGINE (YP125R)
EAS37P1088

ADJUSTING THE VALVE CLEARANCE

The following procedure applies to all of the
valves.
TIP
1
• Valve clearance adjustment should be made
on a cold engine, at room temperature. 2
• When the valve clearance is to be measured or
adjusted, the piston must be at top dead center 4. Remove:
(TDC) on the compression stroke. • Timing mark accessing plug “1”

1. Remove:
• Storage box
Refer to “GENERAL CHASSIS” on page 4-1.
2. Remove:
• V-belt case cover “1”
• V-belt case air duct “2”
• V-belt case air filter element
1
5. Measure:
• Valve clearance
Out of specification → Adjust.

Valve clearance (cold)

Intake
1 0.10–0.14 mm (0.0039–0.0055 in)
Exhaust
0.22–0.26 mm (0.0087–0.0102 in)

▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼
a. Turn the primary sheave nut on the left side
of the crankshaft counterclockwise to turn the
2 crankshaft.

3. Remove:
• Spark plug cap
• Spark plug “1”
• Cylinder head cover “2”

b. Align the “I” mark “a” on the generator rotor

with the stationary pointer “b” on the genera-
tor cover.

3-6
 ENGINE (YP125R)

c. Turn the adjusting screw “3” in direction “a” or

“b” with the tappet adjusting tool “4” until the
specified valve clearance is obtained.

Direction “a”
Valve clearance is increased.
Direction “b”
Valve clearance is decreased.

Tappet adjusting tool

c. Check that the cam lobes are positioned as 90890-01311
shown in the illustration. Six piece tappet set
YM-A5970

3
d. Measure the valve clearance with a thickness 4
gauge “1”.
Out of specification → Adjust. d. Hold the adjusting screw to prevent it from
moving and tighten the locknut to specifica-
tion.

Locknut (valve clearance adjust-

1 ing screw)
T.
R.

7 Nm (0.7 m·kgf, 5.1 ft·lbf)

e. Measure the valve clearance again.

f. If the valve clearance is still out of specifica-
tion, repeat all of the valve clearance adjust-
ment steps until the specified clearance is
▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲
obtained.
6. Adjust:
▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲
• Valve clearance
7. Install:
▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼
a. Loosen the locknut “1”. • Timing mark accessing plug
b. Insert a thickness gauge “2” between the end (along with the O-ring New )
of the adjusting screw and the valve tip. • Cylinder head cover gasket New
• Cylinder head cover
1 • Spark plug
• Spark plug cap
2
Timing mark accessing plug
8 Nm (0.8 m·kgf, 5.8 ft·lbf)
T.
R.

Cylinder head cover bolt

10 Nm (1.0 m·kgf, 7.2 ft·lbf)
Spark plug
13 Nm (1.3 m·kgf, 9.4 ft·lbf)

3-7
 ENGINE (YP125R)

8. Install:
• V-belt case air filter element
3
• V-belt case air duct FI Diagnostic Tool
• V-belt case cover 2
V-belt case air duct bolt DIAG
7 Nm (0.7 m·kgf, 5.1 ft·lbf)
T.
R.

V-belt case cover bolt 1

7 Nm (0.7 m·kgf, 5.1 ft·lbf)

9. Install:
• Storage box 6. Press the “UP” button to select the CO adjust-
Refer to “GENERAL CHASSIS” on page 4-1. ment mode “CO” or the diagnostic mode “DI-
AG”.
EAS37P1089
7. After selecting “CO”, press the “MODE” but-
ADJUSTING THE EXHAUST GAS VOLUME ton.
TIP 8. Check that “C1” appears on the LCD of the FI
Be sure to set the CO density level to standard, diagnostic tool, and then press the “MODE”
and then adjust the exhaust gas volume. button.
1. Remove: 9. Start the engine.
ECA37P1042
• Upper panel NOTICE
Refer to “GENERAL CHASSIS” on page 4-1.
Perform the adjustment after the battery has
2. Set the main switch to “OFF”.
been sufficiently charged.
3. Disconnect:
• Self-diagnosis signal coupler
4. Connect:
• FI diagnostic tool “1”
FI Diagnostic Tool

FI diagnostic tool 1700rpm

90890-03182 C1 : -10

10.Change the CO adjustment volume by press-

ing the “UP” and “DOWN” buttons.
TIP
The CO adjustment volume and engine idling
speed appears on the LCD of the FI diagnostic
tool.
5. While pressing the “MODE” button “1”, set • To decrease the CO adjustment volume, press
the main switch to “ON”. the “DOWN” button.
• To increase the CO adjustment volume, press
TIP
the “UP” button.
• “DIAG” appears on the LCD “2” of the FI diag-
nostic tool. 11.Release the “DOWN” and “UP” buttons to ex-
• “POWER” LED (Green) “3” comes on. ecute the selection.
12.Set the main switch to “OFF” to cancel the
mode.
13.Disconnect:
• FI diagnostic tool
14.Connect:
• Self-diagnosis signal coupler

3-8
 ENGINE (YP125R)

15.Install: EWA12910

• Upper panel WARNING

Refer to “GENERAL CHASSIS” on page 4-1. After adjusting the throttle cable free play,
start the engine and turn the handlebar to the
EAS37P1090
right and to the left to ensure that this does
ADJUSTING THE THROTTLE CABLE FREE
not cause the engine idling speed to change.
PLAY
1. Check: ▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲
• Throttle cable free play “a” EAS37P1091

Out of specification → Adjust. CHECKING THE SPARK PLUG

1. Disconnect:
Throttle cable free play • Spark plug cap “1”
3.0–5.0 mm (0.12–0.20 in)

a
2. Remove:
• Spark plug
2. Adjust: ECA13330

• Throttle cable free play NOTICE

▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼
a. Slide back the rubber cover “1”. Before removing the spark plug, blow away
b. Loosen the locknut “2”. any dirt accumulated in the spark plug well
c. Turn the adjusting nut “3” in direction “a” or “b” with compressed air to prevent it from falling
until the specified throttle cable free play is into the cylinder.
obtained. 3. Check:
• Spark plug type
Direction “a” Incorrect → Change.
Throttle cable free play is increased.
Direction “b” Manufacturer/model
Throttle cable free play is decreased. NGK/CPR9EA-9

4. Check:
• Electrode “1”
Damage/wear → Replace the spark plug.
• Insulator “2”
Abnormal color → Replace the spark plug.
a Normal color is medium-to-light tan.
5. Clean:
b • Spark plug
(with a spark plug cleaner or wire brush)
2 3 1 6. Measure:
d. Tighten the locknut. • Spark plug gap “a”
e. Slide the rubber cover to its original position. (with a wire thickness gauge)
Out of specification → Regap.

Spark plug gap

0.8–0.9 mm (0.031–0.035 in)

3-9
 ENGINE (YP125R)

1
7. Install: 4. Check:
• Spark plug • Ignition timing
▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼
Spark plug a. Start the engine, warm it up for several min-
13 Nm (1.3 m·kgf, 9.4 ft·lbf) utes, and then let it run at the specified en-
T.
R.

gine idling speed.

TIP
Before installing the spark plug, clean the spark Engine idling speed
plug and gasket surface. 1600–1800 r/min

8. Connect: b. Check that the stationary pointer “a” on the

• Spark plug cap generator cover is within the firing range “b”
EAS37P1092
on the generator rotor.
CHECKING THE IGNITION TIMING Incorrect firing range → Check the ignition
TIP
system.
TIP
Prior to checking the ignition timing, check the
wiring connections of the entire ignition system. The ignition timing is not adjustable.
Make sure that all connections are tight and free
of corrosion.
1. Stand the vehicle on a level surface.
TIP
Place the vehicle on the centerstand.
2. Remove:
• Timing mark accessing plug “1”

▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲
5. Disconnect:
• Timing light
6. Install:
• Timing mark accessing plug
(along with the O-ring New )
1
Timing mark accessing plug
3. Connect: 8 Nm (0.8 m·kgf, 5.8 ft·lbf)
T.
R.

• Timing light “1”

(onto the spark plug lead)

Timing light
90890-03141
Inductive clamp timing light
YU-03141

3-10
 ENGINE (YP125R)

EAS37P1093

MEASURING THE COMPRESSION Standard compression pressure

PRESSURE (at sea level)
TIP 550 kPa/680 r/min (5.5
Insufficient compression pressure will result in a kgf/cm²/680 r/min, 78.2 psi/680
loss of performance. r/min)
Minimum–maximum
1. Remove: 480–620 kPa (4.8–6.2 kgf/cm²,
• Storage box 68.3–88.2 psi)
Refer to “GENERAL CHASSIS” on page 4-1.
2. Measure: ▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼
a. Set the main switch to “ON”.
• Valve clearance
b. With the throttle wide open, crank the engine
Out of specification → Adjust.
until the reading on the compression gauge
Refer to “ADJUSTING THE VALVE CLEAR-
stabilizes.
ANCE” on page 3-6. EWA37P1019

3. Start the engine, warm it up for several min- WARNING

utes, and then turn it off. To prevent sparking, ground the spark plug
4. Disconnect: lead before cranking the engine.
• Spark plug cap
5. Remove: c. If the compression pressure is above the
• Spark plug maximum specification, check the cylinder
ECA37P1043 head, valve surfaces and piston crown for
NOTICE carbon deposits.
Before removing the spark plug, use com- Carbon deposits → Eliminate.
pressed air to blow away any dirt accumulat- d. If the compression pressure is below the min-
ed in the spark plug well to prevent it from imum specification, pour a teaspoonful of en-
falling into the cylinder. gine oil into the spark plug bore and measure
again.
6. Install:
Refer to the following table.
• Compression gauge “1”
Compression pressure (with oil applied into
Compression gauge the cylinder)
90890-03081 Reading Diagnosis
Engine compression tester
YU-33223 Higher than without Piston ring(s) wear or
oil damage → Repair.
Piston, valves, cylin-
1 der head gasket or
Same as without oil piston ring(s) possi-
bly defective → Re-
pair.

▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲
8. Install:
• Spark plug

Spark plug
7. Measure: 13 Nm (1.3 m·kgf, 9.4 ft·lbf)
T.

• Compression pressure
R.

Out of specification → Refer to steps (c) and 9. Connect:

(d). • Spark plug cap
10.Install:
• Storage box
Refer to “GENERAL CHASSIS” on page 4-1.

3-11
 ENGINE (YP125R)

EAS37P1134

CHECKING THE ENGINE OIL LEVEL

1. Stand the vehicle on a level surface. 1
TIP
• Place the vehicle on the centerstand.
• Make sure the vehicle is upright. b
2. Start the engine, warm it up for several min- a
utes, and then turn it off.
3. Remove:
• Dipstick “1”
4. Check: 5. Start the engine, warm it up for several min-
• Engine oil level utes, and then turn it off.
The engine oil level should be between the 6. Check the engine oil level again.
minimum level mark “a” and maximum level TIP
mark “b”. Before checking the engine oil level, wait a few
Below the minimum level mark → Add the minutes until the oil has settled.
recommended engine oil to the proper level.
7. Install:
TIP
• Dipstick
• Before checking the engine oil level, wait a few
minutes until the oil has settled. EAS37P1094

• Do not screw the dipstick in when inspecting CHANGING THE ENGINE OIL
the oil level. 1. Start the engine, warm it up for several min-
utes, and then turn it off.
2. Place a container under the engine oil drain
Type bolt.
SAE 10W-30, SAE 10W-40, SAE
3. Remove:
15W-40, SAE 20W-40 or SAE
20W-50 • Engine oil filler cap “1”
Recommended engine oil grade • Engine oil drain bolt “2”
API service SG type or higher, (along with the gasket)
JASO standard MA

0 10 30 50 70 90 110 130 ˚F

SAE 10W-30
SAE 10W-40
SAE 10W-50
SAE 15W-40
SAE 20W-40 1
SAE 20W-50
–20 –10 0 10 20 30 40 50 ˚C

ECA37P1044

NOTICE
Do not allow foreign materials to enter the
crankcase.

2
4. Drain:
• Engine oil
(completely from the crankcase)

3-12
 ENGINE (YP125R)

5. If the oil filter element is also to be replaced, c. Install the oil strainer cover.
perform the following procedure.
▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼ Oil strainer cover
a. Remove the oil filter element cover “1” and oil 32 Nm (3.2 m·kgf, 23 ft·lbf)

T.
R.
filter element “2”.
b. Install a new O-ring “3”. ▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲

TIP 7. Install:
Be sure to face the “ ” mark “a” on the oil filter • Engine oil drain bolt
element cover in the direction shown in the illus- (along with the gasket New )
tration.
Engine oil drain bolt
20 Nm (2.0 m·kgf, 14 ft·lbf)

T.
R.
8. Fill:
• Crankcase
a (with the specified amount of the recom-
mended engine oil)
1 Engine oil quantity
Total amount
1.60 L (1.69 US qt, 1.41 Imp.qt)
Without oil filter element replace-
ment
1.40 L (1.48 US qt, 1.23 Imp.qt)
With oil filter element replace-
ment
1.50 L (1.59 US qt, 1.32 Imp.qt)

9. Install:
• Engine oil filler cap
10.Start the engine, warm it up for several min-
utes, and then turn it off.
c. Install the new oil filter element and the oil fil- 11.Check:
ter element cover. • Engine
(for engine oil leaks)
Oil filter element cover bolt 12.Check:
10 Nm (1.0 m·kgf, 7.2 ft·lbf) • Engine oil level
T.
R.

Refer to “CHECKING THE ENGINE OIL

▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲ LEVEL” on page 3-12.
6. If the oil strainer is also to be cleaned, per- 13.Check:
form the following procedure. • Engine oil pressure
▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼ ▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼
a. Remove the oil strainer cover “1” and oil a. Slightly loosen the oil check bolt “1”.
strainer “2”.
b. Install a new O-ring “3”.

2 1

3 New
1 1

3-13
 ENGINE (YP125R)

b. Start the engine and keep it idling until engine 2. Start the engine, warm it up for several min-
oil starts to seep from the oil check bolt. If no utes, and then turn it off.
engine oil comes out after one minute, turn 3. Place a container under the final transmis-
the engine off so that it will not seize. sion.
c. Check the engine oil passages and the oil 4. Remove:
pump for damage or leakage. Refer to “OIL • Oil filler cap “1”
PUMP (YP125R)” on page 5-48. • O-ring “2”
d. Start the engine after solving the problem(s)
and check the engine oil pressure again.
e. Tighten the oil check bolt to specification. 1

Oil check bolt 2

7 Nm (0.7 m·kgf, 5.1 ft·lbf)
T.

1
R.

▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲
14.Reset:
• Oil change indicator
▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼
5. Remove:
a. Set the main switch to “ON”.
• Final transmission oil drain bolt “1”
b. Push the “OIL CHANGE” button “1” for 15 to
Completely drain the final transmission oil.
20 seconds.
1

6. Install:
c. Release the button and the oil change indica-
• Final transmission oil drain bolt
tor will go off.
TIP (along with the gasket New )
If the engine oil is changed before the oil change Final transmission oil drain bolt
indicator comes on (i.e., before the periodic oil 20 Nm (2.0 m·kgf, 14 ft·lbf)
T.
R.

change interval has been reached), the oil

change indicator must be reset as soon as pos- 7. Fill:
sible so that it comes on for the next periodic oil • Final transmission oil
change. (specified amount of the recommended final
transmission oil)
▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲
EAS37P1095 Final transmission oil
CHANGING THE FINAL TRANSMISSION OIL Type
1. Stand the vehicle on a level surface. SAE 10W-30 type SE motor oil
TIP Quantity
• Place the vehicle on the centerstand. 0.21 L (0.22 US qt, 0.18 Imp.qt)
• Make sure that the vehicle is upright. Quantity (disassembled)
0.23 L (0.24 US qt, 0.20 Imp.qt)

8. Install:
• O-ring
• Oil filler cap

3-14
 ENGINE (YP125R)

9. Start the engine, warm it up for several min- EAS37P1097

CLEANING THE V-BELT CASE AIR FILTER

utes, turn it off, and then check for oil leak-
ELEMENT
age.
1. Remove:
EAS37P1096 • V-belt case cover “1”
REPLACING THE AIR FILTER ELEMENT • V-belt case air duct “2”
TIP • V-belt case air filter element
Check hoses are located on the bottom of the air
filter case. If dust or water or both collects in a
hose, remove the clamp from the hose, and then
remove the plug to drain the hose.
1. Remove:
• Air filter case cover “1”
• Air filter element
1

1
2

2. Check:
• Air filter element
Damage → Replace.
TIP
2. Clean:
• V-belt case air filter element
• Replace the air filter element every 12000 km
(with solvent)
of operation. EWA37P1020

• The air filter needs more frequent service if you WARNING

are riding in unusually wet or dusty areas. Never use low flash point solvents, such as
3. Install: gasoline, to clean the V-belt case air filter el-
• Air filter element ement. Such solvents may cause a fire or an
• Air filter case cover explosion.
ECA37P1045

NOTICE TIP
Never operate the engine without the air filter After cleaning, gently squeeze the V-belt case
element installed. Unfiltered air will cause air filter element to remove the excess solvent.
rapid wear of engine parts and may damage ECA37P1046

the engine. Operating the engine without the NOTICE

air filter element will also affect the throttle Do not twist the V-belt case air filter element
body tuning, leading to poor engine perfor- when squeezing it.
mance and possible overheating.
TIP
When installing the air filter element into the air
filter case cover, make sure that the sealing sur-
faces are aligned to prevent any air leaks.

3-15
 ENGINE (YP125R)

EAS37P1099

CHECKING THE FUEL HOSE

1. Remove:
• Storage box
Refer to “GENERAL CHASSIS” on page 4-1.
2. Check:
• Fuel hose “1”
Cracks/damage → Replace the fuel injector
assembly.
Loose connection → Connect properly.
3. Check: 1
• V-belt case air filter element
Damage → Replace.
4. Apply the recommended oil to the entire sur-
face of the V-belt case air filter element and
squeeze out the excess oil. The V-belt case
air filter element should be wet but not drip-
ping.

Recommended oil
Engine oil 3. Install:
• Storage box
5. Install: Refer to “GENERAL CHASSIS” on page 4-1.
• V-belt case air filter element
EAS37P1100
• V-belt case air duct CHECKING THE BREATHER HOSES
• V-belt case cover 1. Remove:
V-belt case air duct bolt • Storage box
7 Nm (0.7 m·kgf, 5.1 ft·lbf) Refer to “GENERAL CHASSIS” on page 4-1.
T.
R.

V-belt case cover bolt 2. Check:

7 Nm (0.7 m·kgf, 5.1 ft·lbf) • Cylinder head breather hose “1”
• Transmission case breather hose “2”
EAS37P1098 Cracks/damage → Replace.
CHECKING THE THROTTLE BODY JOINT Loose connection → Connect properly.
1. Remove: ECA37P1047

• Storage box NOTICE

Refer to “GENERAL CHASSIS” on page 4-1. Make sure the cylinder head breather hose
2. Check: and transmission case breather hose are
• Throttle body joint “1” routed correctly.
Cracks/damage → Replace.
1

3. Install:
• Storage box
Refer to “GENERAL CHASSIS” on page 4-1.

3-16
 ENGINE (YP125R)

3. Install:
• Storage box
Refer to “GENERAL CHASSIS” on page 4-1.
3
EAS37P1101

CHECKING THE EXHAUST SYSTEM 2

1. Check:
• Exhaust pipe “1” 3 1
• Muffler “2”
Cracks/damage → Replace.
• Exhaust system connection
Exhaust gas leaks → Replace the gaskets
EAS37P1102
“3”. CHECKING THE COOLANT LEVEL
2. Check: 1. Stand the vehicle on a level surface.
• Tightening torque
TIP
Exhaust pipe nut • Place the vehicle on the centerstand.
20 Nm (2.0 m·kgf, 14 ft·lbf) • Make sure the vehicle is upright.
T.
R.

Muffler joint bolt

2. Check:
14 Nm (1.4 m·kgf, 10 ft·lbf)
Muffler mounting bolt • Coolant level
53 Nm (5.3 m·kgf, 38 ft·lbf) The coolant level should be between the
O2 sensor maximum level mark “a” and minimum level
45 Nm (4.5 m·kgf, 32 ft·lbf) mark “b”.
Below the minimum level mark → Add the
recommended coolant to the proper level.
ECA37P1048

NOTICE
• Adding water instead of coolant lowers the
antifreeze content of the coolant. If water is
used instead of coolant, check, and if nec-
essary, correct the antifreeze concentra-
tion of the coolant.
• Use only distilled water. However, if dis-
tilled water is not available, soft water may
be used.

3-17
 ENGINE (YP125R)

a
6
b

3. Start the engine, warm it up for several min- 3. Install:

utes, and then turn it off. • Footrest board
4. Check: • Bottom cover
• Coolant level • Storage box
TIP Refer to “GENERAL CHASSIS” on page 4-1.
Before checking the coolant level, wait a few EAS37P1104
minutes until it settles. CHANGING THE COOLANT
1. Remove:
EAS37P1103
• Bottom cover
CHECKING THE COOLING SYSTEM
Refer to “GENERAL CHASSIS” on page 4-1.
1. Remove:
2. Remove:
• Storage box
• Coolant reservoir cap “1”
• Bottom cover
3. Disconnect:
• Footrest board
• Coolant reservoir hose “2”
Refer to “GENERAL CHASSIS” on page 4-1.
2. Check:
• Radiator “1” 1
• Radiator inlet hose “2”
• Radiator outlet hose “3”
• Radiator filler hose “4”
• Coolant reservoir hose “5”
• Thermostat cover “6”
• Thermostat inlet hose “7”
Cracks/damage → Replace. 2
Refer to “RADIATOR (YP125R)” on page 6-1
4. Drain:
and “THERMOSTAT (YP125R)” on page 6-3.
• Coolant
(from the coolant reservoir)
5. Remove:
2 • Radiator cap “1”
5 EWA37P1021

WARNING
1 3 A hot radiator is under pressure. Therefore,
do not remove the radiator cap when the en-
4 gine is hot. Scalding hot fluid and steam may
be blown out, which could cause serious in-
jury. When the engine has cooled, open the
radiator cap as follows:
Place a thick rag or a towel over the radiator
cap and slowly turn the radiator cap counter-
clockwise to allow any residual pressure to
escape. When the hissing sound has
stopped, remove the cap.

3-18
 ENGINE (YP125R)

TIP
The specified amount of coolant is a standard
amount. Fill the cooling system with coolant until
coolant comes out of the air bleed bolt hole “1”.

6. Remove:
• Coolant drain bolt (from the cylinder) “1”
(along with the copper washer)

Handling notes for coolant

1 Coolant is potentially harmful and should be
handled with special care.
EWA13040

WARNING
• If coolant splashes in your eyes, thorough-
ly wash them with water and consult a doc-
tor.
7. Drain: • If coolant splashes on your clothes, quickly
• Coolant wash it away with water and then with soap
(from the engine and radiator) and water.
8. Install: • If coolant is swallowed, induce vomiting
• Coolant drain bolt (to the cylinder) and get immediate medical attention.
ECA37P1049
(along with the copper washer New ) NOTICE
Coolant drain bolt • Adding water instead of coolant lowers the
7 Nm (0.7 m·kgf, 5.1 ft·lbf) antifreeze content of the coolant. If water is
T.
R.

used instead of coolant, check, and if nec-

9. Connect: essary, correct the antifreeze concentra-
• Coolant reservoir hose tion of the coolant.
10.Fill: • Use only distilled water. However, if dis-
• Cooling system tilled water is not available, soft water may
(with the specified amount of the recom- be used.
mended coolant) • If coolant comes into contact with painted
surfaces, immediately wash them with wa-
Recommended antifreeze ter.
High-quality ethylene glycol anti- • Do not mix different types of antifreeze.
freeze containing corrosion in-
hibitors for aluminum engines 11.Install:
Mixing ratio • Radiator cap
1:1 (antifreeze:water) 12.Fill:
Radiator capacity (including all • Coolant reservoir
routes) (with the recommended coolant to the maxi-
1.00 L (1.06 US qt, 0.88 Imp.qt) mum level mark “a”)
Coolant reservoir capacity (up to
the maximum level mark)
0.25 L (0.26 US qt, 0.22 Imp.qt)

3-19
 ENGINE (YP125R)

13.Install:
• Coolant reservoir cap
14.Start the engine, warm it up for several min-
utes, and then turn it off.
15.Check:
• Coolant level
Refer to “CHECKING THE COOLANT LEV-
EL” on page 3-17.
TIP
Before checking the coolant level, wait a few
minutes until the coolant has settled.
16.Install:
• Bottom cover
Refer to “GENERAL CHASSIS” on page 4-1.

3-20
 ENGINE (YP250R)

EAS20470

ENGINE (YP250R)
EAS20520

ADJUSTING THE VALVE CLEARANCE

The following procedure applies to all of the
1
valves.
TIP
• Valve clearance adjustment should be made
on a cold engine, at room temperature.
• When the valve clearance is to be measured or
adjusted, the piston must be at top dead center 5. Measure:
(TDC) on the compression stroke. • Valve clearance
Out of specification → Adjust.
1. Remove:
• Storage box Valve clearance (cold)
Refer to “GENERAL CHASSIS” on page 4-1. Intake
2. Remove: 0.08–0.12 mm (0.0031–0.0047 in)
• V-belt case air filter cover “1” Exhaust
0.16–0.20 mm (0.0063–0.0079 in)

▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼
a. Turn the primary sheave nut on the left side
of the crankshaft counterclockwise to turn the
crankshaft.

3. Remove:
• Spark plug cap “1”
• Spark plug
• Tappet covers “2”
• Camshaft sprocket cover “3”
b. When the piston is at TDC on the compres-
2 sion stroke, align the “I” mark “a” on the cam-
shaft sprocket with the stationary pointer “b”
3 on the cylinder head.

b
2 a
1

4. Remove:
• Timing mark accessing plug “1”

c. Align the “I” mark “c” on the generator rotor

with the stationary pointer “d” on the genera-
tor cover.

3-21
 ENGINE (YP250R)

Tappet adjusting tool

90890-01311
Six piece tappet set
YM-A5970

d. Measure the valve clearance with a thickness

gauge “1”. a
Out of specification → Adjust. 3 4

d. Hold the adjusting screw to prevent it from

moving and tighten the locknut to specifica-
tion.

1 Locknut (valve clearance adjust-

ing screw)
T.
R.

14 Nm (1.4 m·kgf, 10 ft·lbf)

▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲ e. Measure the valve clearance again.

6. Adjust: f. If the valve clearance is still out of specifica-
• Valve clearance tion, repeat all of the valve clearance adjust-
▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼
ment steps until the specified clearance is
a. Loosen the locknut “1”. obtained.
b. Insert a thickness gauge “2” between the end ▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲
of the adjusting screw and the valve tip. 7. Install:
1 • Timing mark accessing plug
(along with the O-ring New )
• Camshaft sprocket cover
(along with the O-ring New )
• Tappet covers
(along with the O-rings New )
2 • Spark plug
• Spark plug cap

c. Turn the adjusting screw “3” in direction “a” or Timing mark accessing plug
“b” with the tappet adjusting tool “4” until the 8 Nm (0.8 m·kgf, 5.8 ft·lbf)
T.
R.

Camshaft sprocket cover

specified valve clearance is obtained.
10 Nm (1.0 m·kgf, 7.2 ft·lbf)
Tappet cover
Direction “a”
10 Nm (1.0 m·kgf, 7.2 ft·lbf)
Valve clearance is increased.
Spark plug
Direction “b”
18 Nm (1.8 m·kgf, 13 ft·lbf)
Valve clearance is decreased.
8. Install:
• V-belt case air filter cover
9. Install:
• Storage box
Refer to “GENERAL CHASSIS” on page 4-1.

3-22
 ENGINE (YP250R)

EAS20600
6. Press the “UP” button to select the CO adjust-
ADJUSTING THE EXHAUST GAS VOLUME
ment mode “CO” or the diagnostic mode “DI-
TIP AG”.
Be sure to set the CO density level to standard, 7. After selecting “CO”, press the “MODE” but-
and then adjust the exhaust gas volume. ton.
1. Remove: 8. Check that “C1” appears on the LCD of the FI
• Upper panel diagnostic tool, and then press the “MODE”
Refer to “GENERAL CHASSIS” on page 4-1. button.
2. Set the main switch to “OFF”. 9. Start the engine.
ECA37P1015
3. Disconnect: NOTICE
• Self-diagnosis signal coupler
Perform the adjustment after the battery has
4. Connect:
been sufficiently charged.
• FI diagnostic tool “1”

FI diagnostic tool
90890-03182
FI Diagnostic Tool

1 1550rpm
C1 : -10

10.Change the CO adjustment volume by press-

ing the “UP” and “DOWN” buttons.
TIP
5. While pressing the “MODE” button “1”, set The CO adjustment volume and engine idling
the main switch to “ON”. speed appears on the LCD of the FI diagnostic
tool.
TIP
• To decrease the CO adjustment volume, press
• “DIAG” appears on the LCD “2” of the FI diag- the “DOWN” button.
nostic tool. • To increase the CO adjustment volume, press
• “POWER” LED (Green) “3” comes on. the “UP” button.
11.Release the “DOWN” and “UP” buttons to ex-
3 ecute the selection.
FI Diagnostic Tool 12.Set the main switch to “OFF” to cancel the
2 mode.
DIAG 13.Disconnect:
• FI diagnostic tool
1 14.Connect:
• Self-diagnosis signal coupler
15.Install:
• Upper panel
Refer to “GENERAL CHASSIS” on page 4-1.
EAS20640

ADJUSTING THE THROTTLE CABLE FREE

PLAY
1. Check:
• Throttle cable free play “a”
Out of specification → Adjust.

3-23
 ENGINE (YP250R)

Throttle cable free play

3.0–5.0 mm (0.12–0.20 in)

2. Remove:
a
• Spark plug
ECA13330

NOTICE
2. Adjust: Before removing the spark plug, blow away
• Throttle cable free play any dirt accumulated in the spark plug well
▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼
a. Slide back the rubber cover “1”. with compressed air to prevent it from falling
b. Loosen the locknut “2”. into the cylinder.
c. Turn the adjusting nut “3” in direction “a” or “b” 3. Check:
until the specified throttle cable free play is • Spark plug type
obtained. Incorrect → Change.

Direction “a” Manufacturer/model

Throttle cable free play is increased. NGK/DPR8EA-9
Direction “b”
Throttle cable free play is decreased. 4. Check:
• Electrode “1”
Damage/wear → Replace the spark plug.
• Insulator “2”
Abnormal color → Replace the spark plug.
Normal color is medium-to-light tan.
5. Clean:
a • Spark plug
(with a spark plug cleaner or wire brush)
6. Measure:
b
• Spark plug gap “a”
2 3 1 (with a wire thickness gauge)
d. Tighten the locknut. Out of specification → Regap.
e. Slide the rubber cover to its original position.
EWA12910 Spark plug gap
WARNING 0.8–0.9 mm (0.031–0.035 in)
After adjusting the throttle cable free play,
start the engine and turn the handlebar to the
right and to the left to ensure that this does
not cause the engine idling speed to change.
▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲
EAS20690

CHECKING THE SPARK PLUG

1. Disconnect:
• Spark plug cap “1”

7. Install:
• Spark plug

3-24
 ENGINE (YP250R)

4. Check:
Spark plug • Ignition timing
18 Nm (1.8 m·kgf, 13 ft·lbf) ▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼
T.
R.

a. Start the engine, warm it up for several min-

TIP utes, and then let it run at the specified en-
Before installing the spark plug, clean the spark gine idling speed.
plug and gasket surface.
Engine idling speed
8. Connect: 1450–1650 r/min
• Spark plug cap
b. Check that the stationary pointer “a” on the
EAS20700

CHECKING THE IGNITION TIMING generator cover is within the firing range “b”
on the generator rotor.
TIP
Incorrect firing range → Check the ignition
Prior to checking the ignition timing, check the system.
wiring connections of the entire ignition system.
TIP
Make sure that all connections are tight and free
of corrosion. The ignition timing is not adjustable.

1. Stand the vehicle on a level surface.

TIP
Place the vehicle on the centerstand.
2. Remove:
• Timing mark accessing plug “1”

▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲
1
5. Disconnect:
• Timing light
6. Install:
• Timing mark accessing plug
(along with the O-ring New )
3. Connect:
• Timing light “1” Timing mark accessing plug
(onto the spark plug lead) 8 Nm (0.8 m·kgf, 5.8 ft·lbf)
T.
R.

Timing light EAS20710

90890-03141 MEASURING THE COMPRESSION

Inductive clamp timing light PRESSURE
YU-03141 TIP
Insufficient compression pressure will result in a
loss of performance.
1. Remove:
• Storage box
Refer to “GENERAL CHASSIS” on page 4-1.
2. Measure:
1 • Valve clearance
Out of specification → Adjust.
Refer to “ADJUSTING THE VALVE CLEAR-
ANCE” on page 3-21.

3-25
 ENGINE (YP250R)

3. Start the engine, warm it up for several min- c. If the compression pressure is above the
utes, and then turn it off. maximum specification, check the cylinder
4. Disconnect: head, valve surfaces and piston crown for
• Spark plug cap carbon deposits.
5. Remove: Carbon deposits → Eliminate.
• Spark plug d. If the compression pressure is below the min-
ECA37P1016
imum specification, pour a teaspoonful of en-
NOTICE gine oil into the spark plug bore and measure
Before removing the spark plug, use com- again.
pressed air to blow away any dirt accumulat- Refer to the following table.
ed in the spark plug well to prevent it from Compression pressure (with oil applied into
falling into the cylinder. the cylinder)
6. Install: Reading Diagnosis
• Compression gauge “1”
Higher than without Piston ring(s) wear or
Compression gauge oil damage → Repair.
90890-03081 Piston, valves, cylin-
Engine compression tester der head gasket or
YU-33223 Same as without oil piston ring(s) possi-
bly defective → Re-
pair.
1
▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲
8. Install:
• Spark plug

Spark plug
18 Nm (1.8 m·kgf, 13 ft·lbf)
T.
R.

9. Connect:
• Spark plug cap
7. Measure: 10.Install:
• Compression pressure • Storage box
Out of specification → Refer to steps (c) and Refer to “GENERAL CHASSIS” on page 4-1.
(d).
EAS20740

Standard compression pressure CHECKING THE ENGINE OIL LEVEL

(at sea level) 1. Stand the vehicle on a level surface.
1400 kPa/500 r/min (14.0 TIP
kgf/cm²/500 r/min, 199.1 psi/500
• Place the vehicle on the centerstand.
r/min)
Minimum–maximum • Make sure the vehicle is upright.
1120–1570 kPa (11.2–15.7 2. Start the engine, warm it up for several min-
kgf/cm², 159.3–223.3 psi) utes, and then turn it off.
3. Remove:
▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼
a. Set the main switch to “ON”. • Dipstick “1”
b. With the throttle wide open, crank the engine 4. Check:
until the reading on the compression gauge • Engine oil level
stabilizes. The engine oil level should be between the
EWA37P1002 minimum level mark “a” and maximum level
WARNING mark “b”.
To prevent sparking, ground the spark plug Below the minimum level mark → Add the
lead before cranking the engine. recommended engine oil to the proper level.

3-26
 ENGINE (YP250R)

EAS20780
TIP CHANGING THE ENGINE OIL
• Before checking the engine oil level, wait a few 1. Start the engine, warm it up for several min-
minutes until the oil has settled. utes, and then turn it off.
• Do not screw the dipstick in when inspecting 2. Place a container under the engine oil drain
the oil level. bolt.
3. Remove:
Type • Engine oil filler cap “1”
SAE 10W-30, SAE 10W-40, SAE • Engine oil drain bolt “2”
15W-40, SAE 20W-40 or SAE (along with the gasket)
20W-50
Recommended engine oil grade
API service SF, SG type or high-
er, JASO standard MA
1
0 10 30 50 70 90 110 130 ˚F

SAE 10W-30
SAE 10W-40
SAE 10W-50
SAE 15W-40
SAE 20W-40
SAE 20W-50
–20 –10 0 10 20 30 40 50 ˚C

EWA37P1003 2
NOTICE
Do not allow foreign materials to enter the
crankcase.

1 4. Drain:
• Engine oil
(completely from the crankcase)
1
5. If the oil strainer is also to be cleaned, per-
b form the following procedure.
a ▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼
a. Remove the oil strainer cover “1” and oil
strainer “2”.
b. Install a new O-ring “3”.
5. Start the engine, warm it up for several min-
utes, and then turn it off.
6. Check the engine oil level again.
TIP
Before checking the engine oil level, wait a few
minutes until the oil has settled. 2

7. Install: 3 New
• Dipstick 1

c. Install the oil strainer cover.

3-27
 ENGINE (YP250R)

c. Check the engine oil passages and the oil

Oil strainer cover pump for damage or leakage. Refer to “OIL
32 Nm (3.2 m·kgf, 23 ft·lbf) PUMP (YP250R)” on page 5-108.
T.
R.

d. Start the engine after solving the problem(s)

▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲
and check the engine oil pressure again.
6. Install: e. Tighten the oil check bolt to specification.
• Engine oil drain bolt
(along with the gasket New ) Oil check bolt
7 Nm (0.7 m·kgf, 5.1 ft·lbf)

T.
R.
Engine oil drain bolt
20 Nm (2.0 m·kgf, 14 ft·lbf) ▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲
T.
R.

13.Reset:
7. Fill: • Oil change indicator
• Crankcase ▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼
(with the specified amount of the recom- a. Set the main switch to “ON”.
mended engine oil) b. Push the “OIL CHANGE” button “1” for 15 to
20 seconds.
Engine oil quantity
Total amount
1.50 L (1.59 US qt, 1.32 Imp.qt)
Periodic oil change
1.30 L (1.37 US qt, 1.14 Imp.qt)

8. Install:
• Engine oil filler cap
9. Start the engine, warm it up for several min- 1
utes, and then turn it off.
10.Check:
• Engine c. Release the button and the oil change indica-
(for engine oil leaks) tor will go off.
11.Check: TIP
• Engine oil level If the engine oil is changed before the oil change
Refer to “CHECKING THE ENGINE OIL indicator comes on (i.e., before the periodic oil
LEVEL” on page 3-26. change interval has been reached), the oil
12.Check: change indicator must be reset as soon as pos-
• Engine oil pressure sible so that it comes on for the next periodic oil
▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼ change.
a. Slightly loosen the oil check bolt “1”.
▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲
EAS20830

CHANGING THE FINAL TRANSMISSION OIL

1. Stand the vehicle on a level surface.
TIP
• Place the vehicle on the centerstand.
1 • Make sure that the vehicle is upright.
2. Start the engine, warm it up for several min-
utes, and then turn it off.
3. Place a container under the final transmis-
b. Start the engine and keep it idling until engine
sion.
oil starts to seep from the oil check bolt. If no
4. Remove:
engine oil comes out after one minute, turn
• Oil filler cap “1”
the engine off so that it will not seize.
• O-ring “2”

3-28
 ENGINE (YP250R)

9. Start the engine, warm it up for several min-

utes, turn it off, and then check for oil leak-
1
age.
2 EAS20960

REPLACING THE AIR FILTER ELEMENT

TIP
Check hoses are located on the bottom of the air
filter case. If dust or water or both collects in a
hose, remove the clamp from the hose, and then
remove the plug to drain the hose.
5. Remove:
• Final transmission oil drain bolt “1” 1. Remove:
Completely drain the final transmission oil. • Air filter case cover “1”
• Air filter element

6. Install:
• Final transmission oil drain bolt 2. Check:
(along with the gasket New ) • Air filter element
Damage → Replace.
Final transmission oil drain bolt TIP
22 Nm (2.2 m·kgf, 16 ft·lbf) • Replace the air filter element every 20000 km
T.
R.

of operation.
7. Fill:
• The air filter needs more frequent service if you
• Final transmission oil
are riding in unusually wet or dusty areas.
(specified amount of the recommended final
transmission oil) 3. Install:
• Air filter element
Final transmission oil • Air filter case cover
Type ECA37P1017

SAE 10W-30 type SE motor oil NOTICE

Quantity Never operate the engine without the air filter
0.25 L (0.26 US qt, 0.22 Imp.qt) element installed. Unfiltered air will cause
rapid wear of engine parts and may damage
8. Install:
the engine. Operating the engine without the
• O-ring
air filter element will also affect the throttle
• Oil filler cap
body tuning, leading to poor engine perfor-
mance and possible overheating.
TIP
When installing the air filter element into the air
filter case cover, make sure that the sealing sur-
faces are aligned to prevent any air leaks.

3-29
 ENGINE (YP250R)

EAS20980

CLEANING THE V-BELT CASE AIR FILTER

ELEMENT
1. Remove:
• V-belt case air filter cover “1”
• V-belt case air filter element

3. Install:
• Storage box
Refer to “GENERAL CHASSIS” on page 4-1.
EAS21030
1
CHECKING THE FUEL HOSE
2. Clean: 1. Remove:
• V-belt case air filter element “1” • Storage box
Blow compressed air onto the outer surface Refer to “GENERAL CHASSIS” on page 4-1.
of the V-belt case air filter element. 2. Check:
• Fuel hose “1”
1 Cracks/damage → Replace the fuel injector
assembly.
Loose connection → Connect properly.

1
3. Check:
• V-belt case air filter element
Damage → Replace.
ECA13440

NOTICE 3. Install:
Since the V-belt case air filter element is a • Storage box
dry type, do not let grease or water contact it. Refer to “GENERAL CHASSIS” on page 4-1.
4. Install: EAS21070

• V-belt case air filter element CHECKING THE BREATHER HOSES

• V-belt case air filter cover 1. Remove:
• Storage box
EAS21020
Refer to “GENERAL CHASSIS” on page 4-1.
CHECKING THE THROTTLE BODY JOINT
2. Check:
1. Remove:
• Cylinder head breather hose “1”
• Storage box
• Transmission case breather hose “2”
Refer to “GENERAL CHASSIS” on page 4-1.
Cracks/damage → Replace.
2. Check:
Loose connection → Connect properly.
• Throttle body joint “1” ECA37P1018

Cracks/damage → Replace. NOTICE

Make sure the cylinder head breather hose
and transmission case breather hose are
routed correctly.

3-30
 ENGINE (YP250R)

2
3

2 1 3

3. Install:
• Storage box EAS21110

CHECKING THE COOLANT LEVEL

Refer to “GENERAL CHASSIS” on page 4-1.
1. Stand the vehicle on a level surface.
EAS21080
TIP
CHECKING THE EXHAUST SYSTEM
• Place the vehicle on the centerstand.
1. Check:
• Make sure the vehicle is upright.
• Exhaust pipe “1”
• Muffler “2” 2. Check:
Cracks/damage → Replace. • Coolant level
• Exhaust system connection The coolant level should be between the
Exhaust gas leaks → Replace the gasket “3”. maximum level mark “a” and minimum level
2. Check: mark “b”.
• Tightening torque Below the minimum level mark → Add the
recommended coolant to the proper level.
Exhaust pipe nut ECA37P1019

20 Nm (2.0 m·kgf, 14 ft·lbf) NOTICE

T.
R.

Muffler joint bolt •Adding water instead of coolant lowers the

14 Nm (1.4 m·kgf, 10 ft·lbf) antifreeze content of the coolant. If water is
Muffler mounting bolt
used instead of coolant, check, and if nec-
65 Nm (6.5 m·kgf, 47 ft·lbf)
O2 sensor essary, correct the antifreeze concentra-
tion of the coolant.
45 Nm (4.5 m·kgf, 32 ft·lbf)
•Use only distilled water. However, if distilled
water is not available, soft water may be
used.

3-31
 ENGINE (YP250R)

a 7
b 6

3. Start the engine, warm it up for several min- 3. Install:

utes, and then turn it off. • Footrest board
4. Check: • Bottom cover
• Coolant level • Storage box
TIP Refer to “GENERAL CHASSIS” on page 4-1.
Before checking the coolant level, wait a few EAS21130
minutes until it settles. CHANGING THE COOLANT
1. Remove:
EAS21120
• Bottom cover
CHECKING THE COOLING SYSTEM
Refer to “GENERAL CHASSIS” on page 4-1.
1. Remove:
2. Remove:
• Storage box
• Coolant reservoir cap “1”
• Bottom cover
3. Disconnect:
• Footrest board
• Coolant reservoir hose “2”
Refer to “GENERAL CHASSIS” on page 4-1.
2. Check:
• Radiator “1” 1
• Radiator inlet hose “2”
• Radiator outlet hose “3”
• Radiator filler hose “4”
• Coolant reservoir hose “5”
• Thermostat cover “6”
• Thermostat inlet hose “7”
Cracks/damage → Replace. 2
Refer to “RADIATOR (YP250R)” on page 6-8
4. Drain:
and “THERMOSTAT (YP250R)” on page
• Coolant
6-10.
(from the coolant reservoir)
5. Remove:
• Radiator cap “1”
2 EWA37P1004

5 WARNING
A hot radiator is under pressure. Therefore,
1 do not remove the radiator cap when the en-
4 3 gine is hot. Scalding hot fluid and steam may
be blown out, which could cause serious in-
jury. When the engine has cooled, open the
radiator cap as follows:
Place a thick rag or a towel over the radiator
cap and slowly turn the radiator cap counter-
clockwise to allow any residual pressure to
escape. When the hissing sound has
stopped, remove the cap.

3-32
 ENGINE (YP250R)

TIP
The specified amount of coolant is a standard
amount. Fill the cooling system with coolant until
coolant comes out of the air bleed bolt hole “1”.

1
1

6. Remove:
• Coolant drain bolt (water pump) “1”
(along with the copper washer)

Handling notes for coolant

Coolant is potentially harmful and should be
handled with special care.
EWA13040

WARNING
• If coolant splashes in your eyes, thorough-
1
ly wash them with water and consult a doc-
tor.
• If coolant splashes on your clothes, quickly
7. Drain:
• Coolant wash it away with water and then with soap
and water.
(from the engine and radiator)
• If coolant is swallowed, induce vomiting
8. Install:
• Coolant drain bolt (water pump) and get immediate medical attention.
ECA37P1020
(along with the copper washer New ) NOTICE
Coolant drain bolt (water pump) • Adding water instead of coolant lowers the
10 Nm (1.0 m·kgf, 7.2 ft·lbf) antifreeze content of the coolant. If water is
T.
R.

used instead of coolant, check, and if nec-

9. Connect: essary, correct the antifreeze concentra-
• Coolant reservoir hose tion of the coolant.
10.Fill: • Use only distilled water. However, if dis-
• Cooling system tilled water is not available, soft water may
(with the specified amount of the recom- be used.
mended coolant) • If coolant comes into contact with painted
surfaces, immediately wash them with wa-
Recommended antifreeze ter.
High-quality ethylene glycol an- • Do not mix different types of antifreeze.
tifreeze containing corrosion in-
hibitors for aluminum engines 11.Install:
Mixing ratio • Radiator cap
1:1 (antifreeze:water) 12.Fill:
Radiator capacity (including all • Coolant reservoir
routes) (with the recommended coolant to the maxi-
1.00 L (1.06 US qt, 0.88 Imp.qt) mum level mark “a”)
Coolant reservoir capacity (up to
the maximum level mark)
0.25 L (0.26 US qt, 0.22 Imp.qt)

3-33
 ENGINE (YP250R)

13.Install:
• Coolant reservoir cap
14.Start the engine, warm it up for several min-
utes, and then turn it off.
15.Check:
• Coolant level
Refer to “CHECKING THE COOLANT LEV-
EL” on page 3-31.
TIP
Before checking the coolant level, wait a few
minutes until the coolant has settled.
16.Install:
• Bottom cover
Refer to “GENERAL CHASSIS” on page 4-1.

3-34
 CHASSIS

EAS21140
• When refilling, be careful that water does
CHASSIS not enter the brake master cylinder reser-
EAS21240
voir. Water will significantly lower the boil-
CHECKING THE BRAKE FLUID LEVEL ing point of the brake fluid and could cause
1. Stand the vehicle on a level surface. vapor lock.
TIP ECA13540

NOTICE
• Place the vehicle on the centerstand.
• Make sure the vehicle is upright. Brake fluid may damage painted surfaces
and plastic parts. Therefore, always clean up
2. Check: any spilt brake fluid immediately.
• Brake fluid level
Below the minimum level mark “a” → Add the TIP
recommended brake fluid to the proper level. In order to ensure a correct reading of the brake
fluid level, make sure the top of the brake fluid
Front brake reservoir is horizontal.
Recommended fluid
DOT 4 EAS21250
Rear brake CHECKING THE FRONT BRAKE PADS
Recommended fluid The following procedure applies to all of the
DOT 4
brake pads.
1. Operate the brake.
A 2. Check:
a
• Front brake pad
Wear indicator grooves “a” have almost dis-
appeared → Replace the brake pads as a
set.
Refer to “FRONT BRAKE” on page 4-17.

a a
a

EAS37P1130

CHECKING THE REAR BRAKE PADS

(YP125R)
A. Front brake The following procedure applies to all of the
B. Rear brake brake pads.
EWA13540
1. Operate the brake.
WARNING 2. Check:
• Use only the designated brake fluid. Other • Rear brake pad
brake fluids may cause the rubber seals to Wear limit “a” reached → Replace the brake
deteriorate, causing leakage and poor pads as a set.
brake performance. Refer to “REAR BRAKE” on page 4-29.
• Refill with the same type of brake fluid that Limit
is already in the system. Mixing brake fluids 0.8 mm (0.03 in)
may result in a harmful chemical reaction,
leading to poor brake performance.

3-35
 CHASSIS

EAS21290

CHECKING THE REAR BRAKE HOSE

1. Check:
• Brake hose “1”
Cracks/damage/wear → Replace.
a 2. Check:
• Brake hose holder “2”
Loose connection → Connect.

EAS21260 1
CHECKING THE REAR BRAKE PADS 2
(YP250R)
The following procedure applies to all of the
brake pads.
1. Operate the brake.
2. Check:
• Rear brake pad
B
Wear indicator groove “a” has almost disap-
peared → Replace the brake pads as a set. 1
Refer to “REAR BRAKE” on page 4-29. 2

a a A. YP125R
B. YP250R
3. Hold the vehicle upright and apply the rear
EAS21270
brake several times.
CHECKING THE FRONT BRAKE HOSE 4. Check:
1. Check: • Brake hose
• Brake hose “1” Brake fluid leakage → Replace the damaged
Cracks/damage/wear → Replace. hose.
Refer to “REAR BRAKE” on page 4-29.
EAS21350

BLEEDING THE HYDRAULIC BRAKE

SYSTEM
EWA37P1005

WARNING
1 Bleed the hydraulic brake system whenever:
• The system is disassembled.
• A brake hose is loosened, disconnected or
replaced.
2. Hold the vehicle upright and apply the front • The brake fluid level is very low.
brake several times. • The brake operation is faulty.
3. Check:
TIP
• Brake hose
Brake fluid leakage → Replace the damaged • Be careful not to spill any brake fluid or allow
hose. the brake master cylinder reservoir to overflow.
Refer to “FRONT BRAKE” on page 4-17.

3-36
 CHASSIS

• When bleeding the hydraulic brake system, d. Place the other end of the hose into a con-
make sure there is always enough brake fluid tainer.
before applying the brake. Ignoring this pre- e. Slowly apply the brake several times.
caution could allow air to enter the hydraulic f. Fully pull the brake lever and hold it in posi-
brake system, considerably lengthening the tion.
bleeding procedure. g. Loosen the bleed screw.
• If bleeding is difficult, it may be necessary to let TIP
the brake fluid settle for a few hours. Repeat Loosening the bleed screw will release the pres-
the bleeding procedure when the tiny bubbles sure and cause the brake lever to contact the
in the hose have disappeared. throttle grip or handlebar grip.
1. Bleed: h. Tighten the bleed screw, and then release
• Hydraulic brake system the brake lever.
▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼
i. Repeat steps (e) to (h) until all of the air bub-
a. Fill the brake master cylinder reservoir to the
bles have disappeared from the brake fluid in
proper level with the recommended brake flu-
the plastic hose.
id.
j. Tighten the bleed screw to specification.
b. Install the brake master cylinder reservoir di-
aphragm. Front brake caliper bleed screw
c. Connect a clear plastic hose “1” tightly to the 6 Nm (0.6 m·kgf, 4.3 ft·lbf)
T.
R.
bleed screw “2”. Rear brake caliper bleed screw
A (YP125R)
14 Nm (1.4 m·kgf, 10 ft·lbf)
Rear brake caliper bleed screw
(YP250R)
6 Nm (0.6 m·kgf, 4.3 ft·lbf)
2
k. Fill the brake master cylinder reservoir to the
proper level with the recommended brake flu-
id.
1 Refer to “CHECKING THE BRAKE FLUID
B LEVEL” on page 3-35.
2 EWA13110

WARNING
After bleeding the hydraulic brake system,
check the brake operation.
▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲

1 EAS21510

CHECKING AND ADJUSTING THE

STEERING HEAD
C 1. Stand the vehicle on a level surface.
1 EWA13120

WARNING
Securely support the vehicle so that there is
no danger of it falling over.
TIP
Place the vehicle on a suitable stand so that the
2 front wheel is elevated.
2. Check:
A. Front brake caliper • Steering head
B. Rear brake caliper (YP125R) Grasp the bottom of the front fork legs and
C. Rear brake caliper (YP250R) gently rock the front fork.

3-37
 CHASSIS

Binding/looseness → Adjust the steering EWA13140

head. WARNING
3. Remove: Do not overtighten the lower ring nut.
• Lower handlebar holder
Refer to “STEERING HEAD” on page 4-57. Lower ring nut (final tightening
4. Adjust: torque)

T.
R.
• Steering head 22 Nm (2.2 m·kgf, 16 ft·lbf)
▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼
a. Remove the upper ring nut “1”, the lock wash- d. Check the steering head for looseness or
er “2”, the center ring nut “3” and the rubber binding by turning the front fork all the way in
washer. both directions. If any binding is felt, remove
the lower bracket and check the upper and
lower bearings.
Refer to “STEERING HEAD” on page 4-57.
e. Install the rubber washer.
f. Install the center ring nut.
g. Finger tighten the center ring nut, and then
align the slots of both ring nuts. If necessary,
hold the lower ring nut and tighten the center
ring nut until their slots are aligned.
TIP
b. Loosen the lower ring nut “4”, and then tight- Align the slots by turning the center ring nut in
en it to specification with the steering nut the tightening direction.
wrench “5”.
h. Install the lock washer “2”.
Lower ring nut (initial tightening TIP
torque) Make sure the lock washer tabs “a” sit correctly
T.
R.

38 Nm (3.8 m·kgf, 27 ft·lbf)

in the ring nut slots “b”.

Steering nut wrench

90890-01403
Exhaust flange nut wrench
YU-A9472

TIP
• Be sure to install all the ring nuts with the broad
side of the inner tapered section facing down.
• Set a torque wrench at a right angle to the
steering nut wrench. i. Hold the lower and center ring nuts with a
steering nut wrench and tighten the upper
ring nut with another steering nut wrench.

Steering nut wrench

90890-01403
Exhaust flange nut wrench
YU-A9472

Upper ring nut

75 Nm (7.5 m·kgf, 54 ft·lbf)
T.
R.

c. Loosen the lower ring nut “4” 1/4 of a turn,

and then tighten it to specification with a ▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲
steering nut wrench.

3-38
 CHASSIS

5. Install: Spring preload

• Lower handlebar holder ECA13590

Refer to “STEERING HEAD” on page 4-57. NOTICE

Never go beyond the maximum or minimum
EAS21530
adjustment positions.
CHECKING THE FRONT FORK
1. Stand the vehicle on a level surface. 1. Adjust:
EWA13120
• Spring preload
WARNING ▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼
Securely support the vehicle so that there is a. Turn the adjusting ring “1” in direction “a” or
no danger of it falling over. “b”.
Align the desired position on the adjusting
2. Check:
ring with the stopper “2”.
• Inner tubes
Damage/scratches → Replace. Direction “a”
• Front fork leg Spring preload is increased (suspen-
Oil leaks between inner tube and outer tube sion is harder).
→ Replace the oil seal. Direction “b”
3. Hold the vehicle upright and apply the front Spring preload is decreased (suspen-
brake. sion is softer).
4. Check:
• Front fork operation
Push down hard on the handlebar several Spring preload adjusting positions
times and check if the front fork rebounds Minimum
1
smoothly.
Standard
Rough movement → Repair. 2
Refer to “FRONT FORK” on page 4-50. Maximum
4

a
b
1
2

EAS21630

ADJUSTING THE REAR SHOCK ABSORBER

ASSEMBLIES ▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲
The following procedure applies to both of the EAS21650
rear shock absorber assemblies. CHECKING THE TIRES
EWA37P1006
The following procedure applies to both of the
WARNING
tires.
• Securely support the vehicle so that there 1. Check:
is no danger of it falling over. • Tire pressure
• Always adjust both rear shock absorber as- Out of specification → Regulate.
semblies evenly. Uneven adjustment can
result in poor handling and loss of stability.

3-39
 CHASSIS

Wear limit (front)

1.6 mm (0.06 in)
Wear limit (rear)
1.6 mm (0.06 in)

EWA13180

WARNING
• The tire pressure should only be checked
and regulated when the tire temperature
equals the ambient air temperature.
• The tire pressure and the suspension must
be adjusted according to the total weight 1. Tire tread depth
(including cargo, rider, passenger and ac- 2. Side wall
3. Wear indicator
cessories) and the anticipated riding
speed. EWA14080

• Operation of an overloaded vehicle could WARNING

cause tire damage, an accident or an injury. • Do not use a tubeless tire on a wheel de-
NEVER OVERLOAD THE VEHICLE. signed only for tube tires to avoid tire fail-
ure and personal injury from sudden
Tire air pressure (measured on deflation.
cold tires) • When using a tube tire, be sure to install the
Loading condition correct tube.
0–90 kg (0–198 lb) • Always replace a new tube tire and a new
Front tube as a set.
190 kPa (1.90 kgf/cm², 28 psi) • To avoid pinching the tube, make sure the
Rear wheel rim band and tube are centered in the
220 kPa (2.20 kgf/cm², 32 psi) wheel groove.
Loading condition
• Patching a punctured tube is not recom-
90 kg–maximum load
Front mended. If it is absolutely necessary to do
210 kPa (2.10 kgf/cm², 30 psi) so, use great care and replace the tube as
Rear soon as possible with a good quality re-
250 kPa (2.50 kgf/cm², 36 psi) placement.
Maximum load
186 kg (410 lb)
* Total weight of rider, passenger, cargo
and accessories
EWA13190

WARNING
It is dangerous to ride with a worn-out tire.
When the tire tread reaches the wear limit, re-
place the tire immediately.
2. Check: A. Tire
• Tire surfaces B. Wheel
Damage/wear → Replace the tire.
Tube wheel Tube tire only
Tubeless wheel Tube or tubeless tire

3-40
 CHASSIS

EWA37P1007
1. Check:
WARNING • Wheel
After extensive tests, the tires listed below Damage/out-of-round → Replace.
have been approved by Yamaha Motor Es- EWA13260

paña, S.A. for this model. The front and rear WARNING
tires should always be by the same manufac- Never attempt to make any repairs to the
turer and of the same design. No guarantee wheel.
concerning handling characteristics can be
TIP
given if a tire combination other than one ap-
proved by Yamaha is used on this vehicle. After a tire or wheel has been changed or re-
placed, always balance the wheel.
Front tire
EAS21690
Size CHECKING AND LUBRICATING THE
120/70–15 M/C 56P (PIRELLI)
CABLES
120/70–15 M/C 56S (MICHELIN)
Manufacturer/model The following procedure applies to all of the in-
MICHELIN/GOLD STANDARD ner and outer cables.
EWA37P1008
PIRELLI/GTS23
WARNING
A damaged outer cable may cause the cable
Rear tire to corrode and interfere with its movement.
Size Replace damaged outer cable and inner ca-
140/70–14 M/C 68P (PIRELLI) bles as soon as possible.
140/70–14 M/C 68S (MICHELIN)
Manufacturer/model 1. Check:
MICHELIN/GOLD STANDARD • Outer cable
PIRELLI/GTS24 Damage → Replace.
2. Check:
EWA13210
• Cable operation
WARNING
Rough movement → Lubricate.
New tires have a relatively low grip on the
road surface until they have been slightly Recommended lubricant
worn. Therefore, approximately 100 km Engine oil or a suitable cable lu-
should be traveled at normal speed before bricant
any high-speed riding is done.
TIP
TIP
Hold the cable end upright and pour a few drops
For tires with a direction of rotation mark “1”: of lubricant into the cable sheath or use a suit-
Install the tire with the mark pointing in the direc- able lubricating device.
tion of wheel rotation.
EAS21700

LUBRICATING THE LEVERS

Lubricate the pivoting points and metal-to-metal
moving parts of the levers.

Recommended lubricant
Silicone grease

EAS21720

LUBRICATING THE SIDESTAND

Lubricate the pivoting point and metal-to-metal
EAS21670 moving parts of the sidestand.
CHECKING THE WHEELS
The following procedure applies to both of the Recommended lubricant
wheels. Lithium-soap-based grease

3-41
 CHASSIS

EAS21730

LUBRICATING THE CENTERSTAND

Lubricate the pivoting point and metal-to-metal
moving parts of the centerstand.

Recommended lubricant
Lithium-soap-based grease

3-42
 ELECTRICAL SYSTEM

EAS21750
5. Install:
ELECTRICAL SYSTEM
• Headlight bulb New
EAS21760 Secure the new headlight bulb with the head-
CHECKING AND CHARGING THE BATTERY light bulb holder.
Refer to “ELECTRICAL COMPONENTS” on ECA13690

page 8-71. NOTICE

EAS21770
Avoid touching the glass part of the head-
CHECKING THE FUSES light bulb to keep it free from oil, otherwise
Refer to “ELECTRICAL COMPONENTS” on the transparency of the glass, the life of the
page 8-71. bulb and the luminous flux will be adversely
affected. If the headlight bulb gets soiled,
EAS21780
thoroughly clean it with a cloth moistened
REPLACING A HEADLIGHT BULB
with alcohol or lacquer thinner.
To replace a high beam headlight bulb 6. Install:
1. Remove: • Headlight bulb holder
• Front cowling assembly (with the headlight bulb)
Refer to “GENERAL CHASSIS” on page 4-1. 7. Install:
2. Remove: • Headlight bulb cover
• Headlight bulb cover “1” 8. Install:
• Front cowling assembly
1 Refer to “GENERAL CHASSIS” on page 4-1.

To replace a low beam headlight bulb

1. Remove:
• Front cowling assembly
Refer to “GENERAL CHASSIS” on page 4-1.
2. Remove:
• Headlight bulb cover “1”

3. Remove: 1
• Headlight bulb holder “1”
(with the headlight bulb)

3. Disconnect:
1 • Headlight coupler “1”
4. Detach:
• Headlight bulb holder “2”
4. Remove: 5. Remove:
• Headlight bulb • Headlight bulb “3”
EWA13320
EWA13320

WARNING WARNING
Since the headlight bulb gets extremely hot, Since the headlight bulb gets extremely hot,
keep flammable products and your hands keep flammable products and your hands
away from the bulb until it has cooled down. away from the bulb until it has cooled down.

3-43
 ELECTRICAL SYSTEM

1 2

b a b a

3 1 1

6. Install: c. Install the adjusting screw accessing cap.

• Headlight bulb New ▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲
ECA13690

NOTICE
Avoid touching the glass part of the head-
light bulb to keep it free from oil, otherwise
the transparency of the glass, the life of the
bulb and the luminous flux will be adversely
affected. If the headlight bulb gets soiled,
thoroughly clean it with a cloth moistened
with alcohol or lacquer thinner.
7. Attach:
• Headlight bulb holder
8. Connect:
• Headlight coupler
9. Install:
• Headlight bulb cover
10.Install:
• Front cowling assembly
Refer to “GENERAL CHASSIS” on page 4-1.
EAS21800

ADJUSTING THE HEADLIGHT BEAM

1. Adjust:
• Headlight beam (vertically)
▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼
a. Remove the adjusting screw accessing cap.
b. Turn the adjusting screw “1” in direction “a” or
“b”.

Direction “a”
Headlight beam is raised.
Direction “b”
Headlight beam is lowered.

3-44
 ELECTRICAL SYSTEM

3-45
 CHASSIS

GENERAL CHASSIS....................................................................................... 4-1

REMOVING THE STORAGE BOX............................................................ 4-2
INSTALLING THE SEAT ........................................................................... 4-2

FRONT WHEEL............................................................................................... 4-9

REMOVING THE FRONT WHEEL.......................................................... 4-11
DISASSEMBLING THE FRONT WHEEL................................................ 4-11
CHECKING THE FRONT WHEEL .......................................................... 4-11
ASSEMBLING THE FRONT WHEEL...................................................... 4-12
ADJUSTING THE FRONT WHEEL STATIC BALANCE ......................... 4-12
INSTALLING THE FRONT WHEEL (FRONT BRAKE DISC).................. 4-13

REAR WHEEL ............................................................................................... 4-15

REMOVING THE REAR WHEEL ............................................................ 4-16
CHECKING THE REAR WHEEL............................................................. 4-16
ADJUSTING THE REAR WHEEL STATIC BALANCE............................ 4-16
INSTALLING THE REAR WHEEL (REAR BRAKE DISC) ...................... 4-16

FRONT BRAKE ............................................................................................. 4-17

INTRODUCTION ..................................................................................... 4-22
4
CHECKING THE FRONT BRAKE DISC ................................................. 4-22
REPLACING THE FRONT BRAKE PADS .............................................. 4-23
REMOVING THE FRONT BRAKE CALIPER.......................................... 4-24
DISASSEMBLING THE FRONT BRAKE CALIPER ................................ 4-24
CHECKING THE FRONT BRAKE CALIPER .......................................... 4-24
ASSEMBLING THE FRONT BRAKE CALIPER ...................................... 4-25
INSTALLING THE FRONT BRAKE CALIPER ........................................ 4-25
REMOVING THE FRONT BRAKE MASTER CYLINDER ....................... 4-26
CHECKING THE FRONT BRAKE MASTER CYLINDER........................ 4-26
ASSEMBLING THE FRONT BRAKE MASTER CYLINDER ................... 4-26
INSTALLING THE FRONT BRAKE MASTER CYLINDER...................... 4-27

REAR BRAKE ............................................................................................... 4-29

INTRODUCTION ..................................................................................... 4-37
CHECKING THE REAR BRAKE DISC.................................................... 4-37
REPLACING THE REAR BRAKE PADS (YP125R)................................ 4-37
REPLACING THE REAR BRAKE PADS (YP250R)................................ 4-38
REMOVING THE REAR BRAKE CALIPER ............................................ 4-39
DISASSEMBLING THE REAR BRAKE CALIPER (YP250R only) .......... 4-39
CHECKING THE REAR BRAKE CALIPER (YP125R) ............................ 4-40
CHECKING THE REAR BRAKE CALIPER (YP250R) ............................ 4-40
ASSEMBLING THE REAR BRAKE CALIPER ........................................ 4-41
INSTALLING THE REAR BRAKE CALIPER (YP125R) .......................... 4-41
INSTALLING THE REAR BRAKE CALIPER (YP250R) .......................... 4-42
REMOVING THE REAR BRAKE MASTER CYLINDER ......................... 4-43
CHECKING THE REAR BRAKE MASTER CYLINDER .......................... 4-43
ASSEMBLING THE REAR BRAKE MASTER CYLINDER...................... 4-44
INSTALLING THE REAR BRAKE MASTER CYLINDER ........................ 4-44
HANDLEBAR ................................................................................................ 4-46
REMOVING THE HANDLEBAR.............................................................. 4-48
CHECKING THE HANDLEBAR .............................................................. 4-48
INSTALLING THE HANDLEBAR ............................................................ 4-48

FRONT FORK................................................................................................ 4-50

REMOVING THE FRONT FORK LEGS.................................................. 4-52
DISASSEMBLING THE FRONT FORK LEGS ........................................ 4-52
CHECKING THE FRONT FORK LEGS .................................................. 4-53
ASSEMBLING THE FRONT FORK LEGS .............................................. 4-53
INSTALLING THE FRONT FORK LEGS ................................................ 4-55

STEERING HEAD.......................................................................................... 4-57

REMOVING THE LOWER BRACKET..................................................... 4-59
CHECKING THE STEERING HEAD ....................................................... 4-59
INSTALLING THE STEERING HEAD ..................................................... 4-59

REAR SHOCK ABSORBER ASSEMBLIES AND SWINGARM................... 4-61

REMOVING THE REAR SHOCK ABSORBER ASSEMBLIES ............... 4-63
REMOVING THE SWINGARM................................................................ 4-63
CHECKING THE REAR SHOCK ABSORBER ASSEMBLY ................... 4-63
CHECKING THE SWINGARM ................................................................ 4-63
INSTALLING THE SWINGARM .............................................................. 4-63
 GENERAL CHASSIS

EAS21830

GENERAL CHASSIS
Removing the seat and storage box
23 Nm (2.3 m•kgf, 17 ft•Ibf)

T.R
23 Nm (2.3 m•kgf, 17 ft•Ibf)

T.R
.
10 Nm (1.0 m•kgf, 7.2 ft•Ibf)
T.R
.

1 LT
LT

12 11 Nm (1.1 m•kgf, 8.0 ft•Ibf)

2

T.R
.
(4)
13
LT
LT

8 3
(4)
10

5
10 Nm (1.0 m•kgf, 7.2 ft•Ibf) 4
T.R
.

7 11 9
LT
4

6 5

11 Nm (1.1 m•kgf, 8.0 ft•Ibf)

6
T.R
.

11 Nm (1.1 m•kgf, 8.0 ft•Ibf)

T.R

10 Nm (1.0 m•kgf, 7.2 ft•Ibf)

.

T.R
.

Order Job/Parts to remove Q’ty Remarks

1 Seat 1
2 Grab bar 2
3 Rear cover 1
4 Tail/brake light assembly coupler 2 Disconnect.
5 Tail/brake light assembly 2
6 Center panel 2
7 Rear panel 2
8 License plate light coupler 1 Disconnect.
9 Mudguard 1
10 Water guard 1
11 Seat lock cable 1 Disconnect.
12 Storage box 1
13 Safety protector 1
For installation, reverse the removal proce-
dure.

4-1
 GENERAL CHASSIS

EAS37P1079
▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼
REMOVING THE STORAGE BOX a. Fold the tabs on the safety protector so that
1. Remove: the holes in each tab are aligned, and then
• Storage box bolts “1” fasten the tabs to the storage box with the
TIP quick fastener screws at the locations “a”
Be sure not to let the storage box bolts fall inside shown in the illustration.
the vehicle when removing them. a

b. Install the storage box, seat lock cable, water

guard, and mudguard to the vehicle.
2. Remove:
c. Pass the license plate light coupler (license
• Storage box “1”
plate light side) through the hole in the safety
TIP protector at the location “b” shown in the illus-
• Unhook the tabs “a” from the storage box. tration, and then connect the coupler.
• Remove the storage box by moving the seat d. Install the rear panels to the vehicle.
hinge “2” in the direction of the arrow shown. e. Align the holes in the safety protector with the
projections on the water guard at the loca-
tions “c” shown in the illustration, and then
a fasten the safety protector with the clips at the
locations where the holes are aligned with the
projections.
TIP
Make sure that the edge of the safety protector
is positioned to the inside of the rear panels at
the location “d” shown in the illustration.

1 c
b

2
d c

▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲
EAS37P1138
2. Install:
INSTALLING THE SEAT
• Mudguard
1. Install:
• Safety protector Mudguard bolt
11 Nm (1.1 m·kgf, 8.0 ft·lbf)
T.
R.

LOCTITE®

4-2
 GENERAL CHASSIS

TIP
When tightening the mudguard bolts, tighten the
center bolt “a” first, and then tighten the side
bolts “b”.

b a

3. Install:
• Seat

Seat nut
10 Nm (1.0 m·kgf, 7.2 ft·lbf)
T.
R.

TIP
Tighten the seat nuts in the proper tightening se-
quence as shown.

2 4
1
3

4-3
 GENERAL CHASSIS

Removing the headlight assembly

10 Nm (1.0 m•kgf, 7.2 ft•Ibf)
T.R
.

7 Nm (0.7 m•kgf, 5.1 ft•Ibf) 3

T.R
.

(6)

7 Nm (0.7 m•kgf, 5.1 ft•Ibf)

T.R
.
LT
LT
LT
4 10 Nm (1.0 m•kgf, 7.2 ft•Ibf)
2
T.R
.

(6)
7 (4) 5

(4)

1 6
7 Nm (0.7 m•kgf, 5.1 ft•Ibf)
T.R
.

Order Job/Parts to remove Q’ty Remarks

1 Logo plate 1
2 Upper panel 1
3 Windshield 1
4 Windshield bracket 1
5 Headlight assembly coupler 1 Disconnect.
6 Front cowling assembly 1
7 Headlight assembly 1
For installation, reverse the removal proce-
dure.

4-4
 GENERAL CHASSIS

Removing the meter assembly

5 1
2

7
(4)

4
(4) (4)

(4)
6

Order Job/Parts to remove Q’ty Remarks

Windshield Refer to “Removing the headlight assembly”.
1 Rearview mirror 2
2 Center handlebar cover 1
3 Upper handlebar cover 1
4 Lower handlebar cover 1
5 Storage compartment molding 1
6 Meter assembly coupler 1 Disconnect.
7 Meter assembly cover 1
8 Meter assembly 1
For installation, reverse the removal proce-
dure.

4-5
 GENERAL CHASSIS

Removing the radiator cover

4

6 1
3
2

Order Job/Parts to remove Q’ty Remarks

Refer to “Removing the seat and storage
Storage box box”.
Front cowling assembly Refer to “Removing the headlight assembly”.
1 Front turn signal light coupler 2 Disconnect.
2 Front upper panel 2
3 Front turn signal light 2
4 Footrest board mat 2
5 Front lower panel 2
6 Radiator cover 1
For installation, reverse the removal proce-
dure.

4-6
 GENERAL CHASSIS

Removing the storage compartment

10 Nm (1.0 m•kgf, 7.2 ft•Ibf)

T.R
.
7 Nm (0.7 m•kgf, 5.1 ft•Ibf)

T.R
.
4

2
11 Nm (1.1 m•kgf, 8.0 ft•Ibf)
T.R
.

Order Job/Parts to remove Q’ty Remarks

Radiator cover Refer to “Removing the radiator cover”.
1 Radiator air duct 1
2 Bottom cover 1
3 Auxiliary DC jack coupler (OPTION) 1 Disconnect.
4 Storage compartment 1
5 Footrest board 1
For installation, reverse the removal proce-
dure.

4-7
 GENERAL CHASSIS

Removing the air filter case assembly

5
3
4 New

(6)

8
9
7

2 (3)

LT 1

LT
9 Nm (0.9 m•kgf, 6.5 ft•Ibf)
T.R
.

9 Nm (0.9 m•kgf, 6.5 ft•Ibf)

T.R
.

Order Job/Parts to remove Q’ty Remarks

Refer to “Removing the seat and storage
Storage box box”.
1 Air filter case cover 1
2 Air filter element 1
3 Intake air temperature sensor coupler 1 Disconnect.
4 Intake air temperature sensor 1
5 Cylinder head breather hose 1 Disconnect.
Disconnect.
6 Breather hose (air filter case to throttle body) 1 YP250R only
7 Air filter case joint screw clamp 1 YP125R
8 Air filter case joint screw clamp 1 YP250R
9 Air filter case 1
For installation, reverse the removal proce-
dure.

4-8
 FRONT WHEEL

EAS21870

FRONT WHEEL
Removing the front wheel and brake disc

23 Nm (2.3 m•kgf, 17 ft•Ibf)

T.R
.
1

LS
LS

4 2
(5)

LT
6
3

70 Nm (7.0 m•kgf, 50 ft•Ibf)

T.R
.

12 Nm (1.2 m•kgf, 8.7 ft•Ibf) 5

T.R
.

Order Job/Parts to remove Q’ty Remarks

1 Front wheel axle pinch bolt 1 Loosen.
2 Front wheel axle 1
3 Front wheel 1
4 Speed sensor 1
5 Spacer 1
6 Front brake disc 1
For installation, reverse the removal proce-
dure.

4-9
 FRONT WHEEL

Disassembling the front wheel

3
2
1 New

LS

Order Job/Parts to remove Q’ty Remarks

1 Oil seal 1
2 Wheel bearing 2
3 Spacer 1
For assembly, reverse the disassembly pro-
cedure.

4-10
 FRONT WHEEL

EAS21890 EAS21920

REMOVING THE FRONT WHEEL CHECKING THE FRONT WHEEL

1. Stand the vehicle on a level surface. 1. Check:
EWA13120
• Wheel axle
WARNING Roll the wheel axle on a flat surface.
Securely support the vehicle so that there is Bends → Replace.
no danger of it falling over. EWA13460

WARNING
TIP
Do not attempt to straighten a bent wheel ax-
Place the vehicle on a suitable stand so that the le.
front wheel is elevated.
2. Remove:
• Front wheel
TIP
Do not apply the front brake lever when remov-
ing the front wheel.

EAS21910

DISASSEMBLING THE FRONT WHEEL

1. Remove:
• Oil seal 2. Check:
• Wheel bearings • Tire
▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼ • Front wheel
a. Clean the surface of the front wheel hub. Damage/wear → Replace.
b. Remove the oil seal “1” with a flat-head Refer to “CHECKING THE TIRES” on page
screwdriver. 3-39 and “CHECKING THE WHEELS” on
TIP page 3-41.
To prevent damaging the wheel, place a rag “2” 3. Measure:
between the screwdriver and the wheel surface. • Radial wheel runout “1”
• Lateral wheel runout “2”
Over the specified limits → Replace.

Radial wheel runout limit

1.0 mm (0.04 in)
Lateral wheel runout limit
0.5 mm (0.02 in)

c. Remove the wheel bearings “3” with a gener-

al bearing puller.

4. Check:
• Wheel bearings
Front wheel turns roughly or is loose → Re-
place the wheel bearings.
• Oil seal
▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲ Damage/wear → Replace.

4-11
 FRONT WHEEL

EAS21960 ▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲
ASSEMBLING THE FRONT WHEEL EAS21970
1. Install: ADJUSTING THE FRONT WHEEL STATIC
• Wheel bearings New BALANCE
▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼ TIP
a. Install the new wheel bearing (right side). • After replacing the tire, wheel or both, the front
ECA37P1029

NOTICE wheel static balance should be adjusted.

• Adjust the front wheel static balance with the
Do not contact the wheel bearing inner race
brake disc installed.
“1” or balls “2”. Contact should be made
only with the outer race “3”. 1. Remove:
• Balancing weight(s)
TIP
2. Find:
Use a socket “4” that matches the diameter of • Front wheel’s heavy spot
the wheel bearing outer race.
TIP
Place the front wheel on a suitable balancing
stand.
▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼
a. Spin the front wheel.
b. When the front wheel stops, put an “X1” mark
at the bottom of the wheel.

b. Install the spacer.

c. Install the new wheel bearing (left side).
TIP
Place a suitable washer “1” between the socket
“2” and the bearing so that both the inner race
“3” and outer race “4” are pressed at the same
time, and then press the bearing until the inner c. Turn the front wheel 90° so that the “X1” mark
race makes contact with the spacer “5”. is positioned as shown.
d. Release the front wheel.
e. When the wheel stops, put an “X2” mark at
the bottom of the wheel.

4-12
 FRONT WHEEL

▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼
a. Turn the front wheel and make sure it stays at
each position shown.

f. Repeat steps (c) through (e) several times

until all the marks come to rest at the same
spot.
g. The spot where all the marks come to rest is b. If the front wheel does not remain stationary
the front wheel’s heavy spot “X”. at all of the positions, rebalance it.
▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲ ▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲

3. Adjust: EAS21990

• Front wheel static balance INSTALLING THE FRONT WHEEL (FRONT

▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼
BRAKE DISC)
a. Install a balancing weight “1” onto the rim ex- 1. Install:
actly opposite the heavy spot “X”. • Front brake disc
TIP
Front brake disc bolt
Start with the lightest weight. 12 Nm (1.2 m·kgf, 8.7 ft·lbf)
T.
R.

LOCTITE®

TIP
• Install the brake disc so that the recessed por-
tion of the bolt hole faces away from the hub.
• Tighten the brake disc bolts in stages and in a
crisscross pattern.

b. Turn the front wheel 90° so that the heavy

spot is positioned as shown.

c. If the heavy spot does not stay in that posi-

tion, install a heavier weight.
d. Repeat steps (b) and (c) until the front wheel
is balanced.
▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲
4. Check:
• Front wheel static balance

4-13
 FRONT WHEEL

2. Check:
• Front brake disc Wheel axle
Refer to “CHECKING THE FRONT BRAKE 70 Nm (7.0 m·kgf, 50 ft·lbf)

T.
R.
DISC” on page 4-22. Wheel axle pinch bolt
23 Nm (2.3 m·kgf, 17 ft·lbf)
3. Lubricate:
• Oil seal lips ECA37P1030

• Speed sensor oil seal lip NOTICE

Before tightening the wheel axle, push down
Recommended lubricant
hard on the handlebar several times and
Lithium-soap-based grease
check if the front fork rebounds smoothly.
4. Install:
• Spacer
• Speed sensor
• Front wheel
TIP
• Make sure that the speed sensor and the
wheel hub are installed with the projection “a”
of the wheel hub inserted in a slot “b” of the
speed sensor.
• When installing the speed sensor, make sure
that the projection on the wheel hub does not
damage the lip of the speed sensor oil seal.
• Make sure that the slot “c” in the speed sensor
fits over the stopper “d” on the outer tube.

b a

d
5. Install:
• Wheel axle
• Wheel axle pinch bolt

4-14
 REAR WHEEL

EAS22020

REAR WHEEL
Removing the rear wheel and brake disc
9 Nm (0.9 m•kgf, 6.5 ft•Ibf)

T.R
.
1

LT
1

LT

5
4
6
LS

2
9 Nm (0.9 m•kgf, 6.5 ft•Ibf) (4)
T.R
.

3 LT

23 Nm (2.3 m•kgf, 17 ft•Ibf)

T.R
.

Order Job/Parts to remove Q’ty Remarks

Refer to “ENGINE REMOVAL (YP125R)” on
Muffler page 5-1 and “ENGINE REMOVAL
(YP250R)” on page 5-61.
Refer to “REAR SHOCK ABSORBER AS-
Swingarm SEMBLIES AND SWINGARM” on page
4-61.
1 Air filter case mounting bolt 2
2 Rear fender 1
3 Rear wheel 1
4 Washer 1 YP125R
5 Spacer 1 YP250R
6 Rear brake disc 1
For installation, reverse the removal proce-
dure.

4-15
 REAR WHEEL

EAS28760

REMOVING THE REAR WHEEL TIP

1. Stand the vehicle on a level surface. Tighten the brake disc bolts in stages and in a
EWA13120 crisscross pattern.
WARNING
Securely support the vehicle so that there is
no danger of it falling over.
TIP
Place the vehicle on the centerstand so that the
rear wheel is elevated. Also, place a suitable
stand under the engine.

EAS22090

CHECKING THE REAR WHEEL

1. Check: 2. Check:
• Tire • Rear brake disc
• Rear wheel Refer to “CHECKING THE REAR BRAKE
Damage/wear → Replace. DISC” on page 4-37.
Refer to “CHECKING THE TIRES” on page 3. Install:
3-39 and “CHECKING THE WHEELS” on • Rear fender
page 3-41. • Air filter case mounting bolts
2. Measure:
• Radial wheel runout Air filter case mounting bolt
9 Nm (0.9 m·kgf, 6.5 ft·lbf)
• Lateral wheel runout
T.
R.

LOCTITE®
Refer to “CHECKING THE FRONT WHEEL”
on page 4-11.
TIP
Radial wheel runout limit Place the rear fender between the air filter case
1.0 mm (0.04 in) and the crankcase, and then install the air filter
Lateral wheel runout limit case mounting bolts.
0.5 mm (0.02 in)

EAS22150

ADJUSTING THE REAR WHEEL STATIC

BALANCE
TIP
• After replacing the tire, wheel or both, the rear
wheel static balance should be adjusted.
• Adjust the rear wheel static balance with the
brake disc installed.
1. Adjust:
• Rear wheel static balance
Refer to “ADJUSTING THE FRONT WHEEL
STATIC BALANCE” on page 4-12.
EAS28770

INSTALLING THE REAR WHEEL (REAR

BRAKE DISC)
1. Install:
• Rear brake disc

Rear brake disc bolt

23 Nm (2.3 m·kgf, 17 ft·lbf)
T.
R.

LOCTITE®

4-16
 FRONT BRAKE

EAS22210

FRONT BRAKE
Removing the front brake pads

40 Nm (4.0 m•kgf, 29 ft•Ibf)

T.R
.
6 Nm (0.6 m•kgf, 4.3 ft•Ibf)
T.R
.

1
2

8
5
3 4 6
6
1
18 Nm (1.8 m•kgf, 13 ft•Ibf)
T.R
.

7
3 Nm (0.3 m•kgf, 2.2 ft•Ibf)
T.R
.

Order Job/Parts to remove Q’ty Remarks

1 Front brake caliper bolt 2
2 Speed sensor lead guide 1
3 Front brake caliper 1
4 Brake pad pin cap 1
5 Brake pad pin 1
6 Front brake pad 2
7 Brake pad spring 1
8 Brake pad support 1
For installation, reverse the removal proce-
dure.

4-17
 FRONT BRAKE

Removing the front brake master cylinder

1
7 Nm (0.7 m•kgf, 5.1 ft•Ibf)

T.R
.
2

S 3

10

11
10 Nm (1.0 m•kgf, 7.2 ft•Ibf)
T.R
.

New 7

6 5
23 Nm (2.3 m•kgf, 17 ft•Ibf)
T.R
.

Order Job/Parts to remove Q’ty Remarks

Refer to “GENERAL CHASSIS” on page
Lower handlebar cover 4-1.
Drain.
Brake fluid Refer to “BLEEDING THE HYDRAULIC
BRAKE SYSTEM” on page 3-36.
1 Brake master cylinder reservoir cap 1
Brake master cylinder reservoir diaphragm hold-
2 1
er
3 Brake master cylinder reservoir diaphragm 1
4 Front brake lever 1
5 Front brake light switch connector 2 Disconnect.
6 Brake hose union bolt 1
7 Copper washer 2
8 Front brake hose 1
9 Front brake master cylinder holder 1
10 Front brake master cylinder 1
11 Front brake light switch 1
For installation, reverse the removal proce-
dure.

4-18
 FRONT BRAKE

Disassembling the front brake master cylinder

1 New

BF

Order Job/Parts to remove Q’ty Remarks

1 Brake master cylinder kit 1
2 Brake master cylinder body 1
For assembly, reverse the disassembly pro-
cedure.

4-19
 FRONT BRAKE

Removing the front brake caliper

40 Nm (4.0 m•kgf, 29 ft•Ibf)

T.R
.
6

4
5

1 2 New
4

23 Nm (2.3 m•kgf, 17 ft•Ibf)

T.R
.

Order Job/Parts to remove Q’ty Remarks

Drain.
Brake fluid Refer to “BLEEDING THE HYDRAULIC
BRAKE SYSTEM” on page 3-36.
1 Brake hose union bolt 1
2 Copper washer 2
3 Front brake hose 1
4 Front brake caliper bolt 2
5 Speed sensor lead guide 1
6 Front brake caliper 1
For installation, reverse the removal proce-
dure.

4-20
 FRONT BRAKE

Disassembling the front brake caliper

6
23 Nm (2.3 m•kgf, 17 ft•Ibf) S
T.R
.

New 8
LT
S

6 Nm (0.6 m•kgf, 4.3 ft•Ibf) New 9

T.R
.

7
BF

10

8 New LT
S

9 New S

13 Nm (1.3 m•kgf, 9.4 ft•Ibf)

T.R
.
11 BF
5

2 4

1
3

18 Nm (1.8 m•kgf, 13 ft•Ibf)

T.R
.

3 Nm (0.3 m•kgf, 2.2 ft•Ibf)

T.R
.

Order Job/Parts to remove Q’ty Remarks

1 Brake pad pin cap 1
2 Brake pad pin 1
3 Front brake pad 2
4 Brake pad spring 1
5 Brake pad support 1
6 Brake caliper bracket 1
7 Brake caliper piston 2
8 Brake caliper piston dust seal 2
9 Brake caliper piston seal 2
10 Bleed screw 1
11 Brake caliper body 1
For assembly, reverse the disassembly pro-
cedure.

4-21
 FRONT BRAKE

EAS22220

INTRODUCTION
EWA14101

WARNING
Disc brake components rarely require disas-
sembly. Therefore, always follow these pre-
ventive measures:
• Never disassemble brake components un-
less absolutely necessary.
• If any connection on the hydraulic brake
system is disconnected, the entire brake
system must be disassembled, drained, ▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲

cleaned, properly filled, and bled after reas- 4. Measure:

sembly. • Brake disc thickness
• Never use solvents on internal brake com- Measure the brake disc thickness at a few dif-
ponents. ferent locations.
• Use only clean or new brake fluid for clean- Out of specification → Replace.
ing brake components.
Brake disc thickness limit
• Brake fluid may damage painted surfaces
4.5 mm (0.18 in)
and plastic parts. Therefore, always clean
up any spilt brake fluid immediately.
• Avoid brake fluid coming into contact with
the eyes as it can cause serious injury.
FIRST AID FOR BRAKE FLUID ENTERING
THE EYES:
• Flush with water for 15 minutes and get im-
mediate medical attention.

EAS22230

CHECKING THE FRONT BRAKE DISC

1. Remove:
• Front wheel 5. Adjust:
Refer to “FRONT WHEEL” on page 4-9. • Brake disc deflection
▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼
2. Check: a. Remove the brake disc.
• Brake disc b. Rotate the brake disc by one bolt hole.
Damage/galling → Replace. c. Install the brake disc.
3. Measure:
• Brake disc deflection Front brake disc bolt
Out of specification → Correct the brake disc 12 Nm (1.2 m·kgf, 8.7 ft·lbf)
T.
R.

deflection or replace the brake disc. LOCTITE®

Brake disc deflection limit TIP

0.15 mm (0.0059 in)
Tighten the brake disc bolts in stages and in a
▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼
crisscross pattern.
a. Place the vehicle on a suitable stand so that
the front wheel is elevated.
b. Before measuring the front brake disc deflec-
tion, turn the handlebar to the left or right to
ensure that the front wheel is stationary.
c. Remove the brake caliper.
d. Hold the dial gauge at a right angle against
the brake disc surface.
e. Measure the deflection 1.5 mm (0.06 in) be-
low the edge of the brake disc.

4-22
 FRONT BRAKE

d. Measure the brake disc deflection. ▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼

e. If out of specification, repeat the adjustment a. Connect a clear plastic hose “1” tightly to the
steps until the brake disc deflection is within bleed screw “2”. Put the other end of the hose
specification. into an open container.
f. If the brake disc deflection cannot be brought b. Loosen the bleed screw and push the brake
within specification, replace the brake disc. caliper pistons into the brake caliper with your
▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲
finger.
6. Install:
• Front wheel 2 1
Refer to “FRONT WHEEL” on page 4-9.
EAS22270

REPLACING THE FRONT BRAKE PADS

TIP
When replacing the brake pads, it is not neces-
sary to disconnect the brake hose or disassem-
ble the brake caliper.
c. Tighten the bleed screw.
1. Measure:
• Brake pad wear limit “a” Bleed screw
Out of specification → Replace the brake 6 Nm (0.6 m·kgf, 4.3 ft·lbf)
T.
R.

pads as a set.
d. Install new brake pad support, new brake pad
Brake pad lining thickness (in- spring and new brake pads.
ner)
▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲
5.0 mm (0.20 in)
Limit 3. Install:
1.5 mm (0.06 in) • Brake pad pin
Brake pad lining thickness (out- • Brake pad pin cap
er) • Front brake caliper
5.0 mm (0.20 in) • Speed sensor lead guide
Limit • Front brake caliper bolts
1.5 mm (0.06 in)
Front brake caliper bolt
40 Nm (4.0 m·kgf, 29 ft·lbf)
T.
R.

4. Check:
a • Brake fluid level
A Below the minimum level mark “a” → Add the
recommended brake fluid to the proper level.
A Refer to “CHECKING THE BRAKE FLUID
LEVEL” on page 3-35.

a
2. Install:
• Brake pad support New
• Brake pad spring New
• Brake pads New
TIP
Always install new brake pads, a new brake pad
spring, and a new brake pad support as a set.

4-23
 FRONT BRAKE

5. Check: EWA13550

• Brake lever operation WARNING

Soft or spongy feeling → Bleed the brake sys- • Cover the brake caliper piston with a rag.
tem. Be careful not to get injured when the pis-
Refer to “BLEEDING THE HYDRAULIC ton is expelled from the brake caliper.
BRAKE SYSTEM” on page 3-36. • Never try to pry out the brake caliper pis-
ton.
EAS22290

REMOVING THE FRONT BRAKE CALIPER

a
TIP
Before removing the brake caliper, drain the
brake fluid from the entire brake system.
1. Remove:
• Brake hose union bolt “1”
• Copper washers “2”
• Front brake hose “3”
TIP
Put the end of the brake hose into a container b. Remove the brake caliper piston dust seals
and pump out the brake fluid carefully. and brake caliper piston seals.
▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲
EAS22380

CHECKING THE FRONT BRAKE CALIPER

Recommended brake component replace-
3 ment schedule
Brake pads If necessary
1
Piston seals Every two years
2 Piston dust seals Every two years
Brake hose Every four years
EAS22320
Every two years and
DISASSEMBLING THE FRONT BRAKE
Brake fluid whenever the brake
CALIPER is disassembled
1. Remove:
• Brake caliper pistons “1” 1. Check:
• Brake caliper piston dust seals “2” • Brake caliper pistons “1”
• Brake caliper piston seals “3” Rust/scratches/wear → Replace the brake
caliper pistons.
• Brake caliper cylinders “2”
Scratches/wear → Replace the brake caliper
3
assembly.
2
• Brake caliper body “3”
Cracks/damage → Replace the brake caliper
assembly.
• Brake fluid delivery passages
3 (brake caliper body)
1
2 Obstruction → Blow out with compressed air.
▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼ EWA37P1010

a. Blow compressed air into the brake hose joint WARNING

opening “a” to force out the pistons from the Whenever a brake caliper is disassembled,
brake caliper. replace the brake caliper piston dust seals
and brake caliper piston seals.

4-24
 FRONT BRAKE

ECA14170

NOTICE
When installing the brake hose onto the
2 brake caliper “1”, make sure the brake pipe
“a” touches the projection “b” on the brake
3
caliper.

1 b
3
2. Check: a
• Brake caliper bracket
Cracks/damage → Replace. 4
EAS22400

ASSEMBLING THE FRONT BRAKE CALIPER 2

EWA37P1011 1
WARNING 2. Remove:
• Before installation, all internal brake com- • Front brake caliper
ponents should be cleaned and lubricated 3. Install:
with clean or new brake fluid. • Brake pad support
• Never use solvents on internal brake com- • Brake pad spring
ponents as they will cause the brake caliper • Brake pads
piston dust seals and brake caliper piston • Brake pad pin
seals to swell and distort. • Brake pad pin cap
• Whenever a brake caliper is disassembled, • Front brake caliper
replace the brake caliper piston dust seals • Speed sensor lead guide
and brake caliper piston seals.
Brake pad pin
Recommended fluid 18 Nm (1.8 m·kgf, 13 ft·lbf)
T.
R.

DOT 4 Brake pad pin cap

3 Nm (0.3 m·kgf, 2.2 ft·lbf)
EAS22420
Front brake caliper bolt
INSTALLING THE FRONT BRAKE CALIPER 40 Nm (4.0 m·kgf, 29 ft·lbf)
1. Install:
Refer to “REPLACING THE FRONT BRAKE
• Front brake caliper “1”
PADS” on page 4-23.
(temporarily)
4. Fill:
• Copper washers “2” New • Brake master cylinder reservoir
• Front brake hose “3” (with the specified amount of the recom-
• Brake hose union bolt “4” mended brake fluid)
Front brake hose union bolt Recommended fluid
23 Nm (2.3 m·kgf, 17 ft·lbf) DOT 4
T.
R.

EWA37P1024
EWA37P1012
WARNING WARNING
Proper brake hose routing is essential to in- • Use only the designated brake fluid. Other
sure safe vehicle operation. Refer to “CABLE brake fluids may cause the rubber seals to
ROUTING (YP125R)” on page 2-29 and “CA- deteriorate, causing leakage and poor
BLE ROUTING (YP250R)” on page 2-75. brake performance.
• Refill with the same type of brake fluid that
is already in the system. Mixing brake fluids
may result in a harmful chemical reaction,
leading to poor brake performance.

4-25
 FRONT BRAKE

• When refilling, be careful that water does TIP

not enter the brake master cylinder reser- To collect any remaining brake fluid, place a
voir. Water will significantly lower the boil- container under the master cylinder and the end
ing point of the brake fluid and could cause of the brake hose.
vapor lock.
ECA13540

NOTICE
Brake fluid may damage painted surfaces
and plastic parts. Therefore, always clean up
3
any spilt brake fluid immediately.
5. Bleed:
• Brake system 2
Refer to “BLEEDING THE HYDRAULIC
1
BRAKE SYSTEM” on page 3-36.
6. Check: EAS22500
• Brake fluid level CHECKING THE FRONT BRAKE MASTER
Below the minimum level mark “a” → Add the CYLINDER
recommended brake fluid to the proper level. 1. Check:
Refer to “CHECKING THE BRAKE FLUID • Brake master cylinder
LEVEL” on page 3-35. Damage/scratches/wear → Replace.
• Brake fluid delivery passages
a (brake master cylinder body)
Obstruction → Blow out with compressed air.
2. Check:
• Brake master cylinder kit
Damage/scratches/wear → Replace.
3. Check:
• Brake master cylinder reservoir cap
• Brake master cylinder reservoir diaphragm
holder
7. Check: • Brake master cylinder reservoir diaphragm
• Brake lever operation Damage/wear → Replace.
Soft or spongy feeling → Bleed the brake sys- 4. Check:
tem. • Front brake hose
Refer to “BLEEDING THE HYDRAULIC Cracks/damage/wear → Replace.
BRAKE SYSTEM” on page 3-36.
EAS22520

EAS22490 ASSEMBLING THE FRONT BRAKE MASTER

REMOVING THE FRONT BRAKE MASTER CYLINDER
CYLINDER EWA13520

WARNING
TIP
Before removing the front brake master cylinder, • Before installation, all internal brake com-
drain the brake fluid from the entire brake sys- ponents should be cleaned and lubricated
tem. with clean or new brake fluid.
• Never use solvents on internal brake com-
1. Remove: ponents.
• Brake hose union bolt “1”
• Copper washers “2” Recommended fluid
• Front brake hose “3” DOT 4

4-26
 FRONT BRAKE

EAS22530

INSTALLING THE FRONT BRAKE MASTER

CYLINDER
1. Install:
a
• Brake master cylinder “1”
2
• Brake master cylinder holder

Brake master cylinder holder bolt

7 Nm (0.7 m·kgf, 5.1 ft·lbf) New 1
T.
R.

3
TIP
• Align the projection “a” on the brake master cyl- 3. Fill:
inder with the hole “b” in the handlebar. • Brake master cylinder reservoir
• First, tighten the front bolt, then the rear bolt. (with the specified amount of the recom-
mended brake fluid)
b 1 Recommended fluid
DOT 4
EWA13540

WARNING
• Use only the designated brake fluid. Other
a brake fluids may cause the rubber seals to
deteriorate, causing leakage and poor
brake performance.
2. Install: • Refill with the same type of brake fluid that
is already in the system. Mixing brake fluids
• Copper washers “1” New may result in a harmful chemical reaction,
• Front brake hose “2” leading to poor brake performance.
• Brake hose union bolt “3” • When refilling, be careful that water does
not enter the brake master cylinder reser-
Brake hose union bolt
23 Nm (2.3 m·kgf, 17 ft·lbf) voir. Water will significantly lower the boil-
T.

ing point of the brake fluid and could cause

R.

EWA37P1024 vapor lock.

WARNING ECA13540

Proper brake hose routing is essential to in- NOTICE

sure safe vehicle operation. Refer to “CABLE Brake fluid may damage painted surfaces
ROUTING (YP125R)” on page 2-29 and “CA- and plastic parts. Therefore, always clean up
BLE ROUTING (YP250R)” on page 2-75. any spilt brake fluid immediately.
ECA14160
4. Bleed:
NOTICE
• Brake system
When installing the brake hose onto the Refer to “BLEEDING THE HYDRAULIC
brake master cylinder, make sure the brake BRAKE SYSTEM” on page 3-36.
pipe touches the projection “a” as shown. 5. Check:
TIP • Brake fluid level
Turn the handlebar to the left and right to make Below the minimum level mark “a” → Add the
sure the brake hose does not touch other parts recommended brake fluid to the proper level.
(e.g., wire harness, cables, leads). Correct if Refer to “CHECKING THE BRAKE FLUID
necessary. LEVEL” on page 3-35.

4-27
 FRONT BRAKE

6. Check:
• Brake lever operation
Soft or spongy feeling → Bleed the brake sys-
tem.
Refer to “BLEEDING THE HYDRAULIC
BRAKE SYSTEM” on page 3-36.

4-28
 REAR BRAKE

EAS22550

REAR BRAKE
Removing the rear brake pads (YP125R)

New 3
4
2 S

14 Nm (1.4 m•kgf, 10 ft•Ibf)

T.R
.
5
6
5

7 Nm (0.7 m•kgf, 5.1 ft•Ibf)

T.R
.

1
40 Nm (4.0 m•kgf, 29 ft•Ibf)
T.R
.

Order Job/Parts to remove Q’ty Remarks

1 Rear brake caliper bolt 2
2 Rear brake caliper 1
3 Brake pad clip 1
4 Brake pad pin 1
5 Rear brake pad 2
6 Brake pad spring 1
For installation, reverse the removal proce-
dure.

4-29
 REAR BRAKE

Removing the rear brake pads (YP250R)

3 6 Nm (0.6 m•kgf, 4.3 ft•Ibf)

T.R
.
5
7 Nm (0.7 m•kgf, 5.1 ft•Ibf)

T.R
.
4
5 2

4
S

27 Nm (2.7 m•kgf, 19 ft•Ibf)

T.R
.
S
1

Order Job/Parts to remove Q’ty Remarks

1 Rear brake caliper retaining bolt 2
2 Rear brake caliper 1
3 Rear brake pad 2
4 Brake pad shim 4
5 Brake pad support 2
For installation, reverse the removal proce-
dure.

4-30
 REAR BRAKE

Removing the rear brake master cylinder

7 Nm (0.7 m•kgf, 5.1 ft•Ibf)

T.R
.
1
9
2

10 5

New 7
S
8

4
11
New 7

6 10 Nm (1.0 m•kgf, 7.2 ft•Ibf)

T.R
.

23 Nm (2.3 m•kgf, 17 ft•Ibf)

T.R
.

Order Job/Parts to remove Q’ty Remarks

Refer to “GENERAL CHASSIS” on page
Lower handlebar cover 4-1.
Drain.
Brake fluid Refer to “BLEEDING THE HYDRAULIC
BRAKE SYSTEM” on page 3-36.
1 Brake master cylinder reservoir cap 1
Brake master cylinder reservoir diaphragm hold-
2 1
er
3 Brake master cylinder reservoir diaphragm 1
4 Rear brake lever 1
5 Rear brake light switch connector 2 Disconnect.
6 Brake hose union bolt 1
7 Copper washer 2
8 Rear brake hose 1
9 Rear brake master cylinder holder 1
10 Rear brake master cylinder 1
11 Rear brake light switch 1
For installation, reverse the removal proce-
dure.

4-31
 REAR BRAKE

Disassembling the rear brake master cylinder

1 New

BF S

Order Job/Parts to remove Q’ty Remarks

1 Brake master cylinder kit 1
2 Brake master cylinder body 1
For assembly, reverse the disassembly pro-
cedure.

4-32
 REAR BRAKE

Removing the rear brake caliper (YP125R)

28 Nm (2.8 m•kgf, 20 ft•Ibf)

T.R
1

.
5

2 New
1

7 Nm (0.7 m•kgf, 5.1 ft•Ibf)

T.R
.

40 Nm (4.0 m•kgf, 29 ft•Ibf)

T.R
.

Order Job/Parts to remove Q’ty Remarks

Drain.
Brake fluid Refer to “BLEEDING THE HYDRAULIC
BRAKE SYSTEM” on page 3-36.
1 Brake hose union bolt 1
2 Copper washer 2
3 Rear brake hose 1
4 Rear brake caliper bolt 2
5 Rear brake caliper 1
For installation, reverse the removal proce-
dure.

4-33
 REAR BRAKE

Removing the rear brake caliper (YP250R)

T.R
.
23 Nm (2.3 m•kgf, 17 ft•Ibf)
1 3

New 2

7 Nm (0.7 m•kgf, 5.1 ft•Ibf)

T.R
.
5

4 40 Nm (4.0 m•kgf, 29 ft•Ibf)

T.R
.

Order Job/Parts to remove Q’ty Remarks

Refer to “ENGINE REMOVAL (YP250R)” on
Muffler page 5-61.
Drain.
Brake fluid Refer to “BLEEDING THE HYDRAULIC
BRAKE SYSTEM” on page 3-36.
1 Brake hose union bolt 1
2 Copper washer 2
3 Rear brake hose 1
4 Rear brake caliper bolt 3
5 Rear brake caliper 1
For installation, reverse the removal proce-
dure.

4-34
 REAR BRAKE

Disassembling the rear brake caliper (YP125R)

14 Nm (1.4 m•kgf, 10 ft•Ibf) 3

T.R
.

4 1 New

Order Job/Parts to remove Q’ty Remarks

1 Brake pad clip 1
2 Brake pad pin 1
3 Rear brake pad 2
4 Brake pad spring 1
5 Bleed screw/cap 1/1
For assembly, reverse the disassembly pro-
cedure.

4-35
 REAR BRAKE

Disassembling the rear brake caliper (YP250R)

6 Nm (0.6 m•kgf, 4.3 ft•Ibf)

T.R
.
S
9 BF

10
S
6
7 New
8 New

1
5

27 Nm (2.7 m•kgf, 19 ft•Ibf) 4

T.R
.

3 5

Order Job/Parts to remove Q’ty Remarks

1 Rear brake caliper retaining bolt 2
2 Brake caliper bracket 1
3 Rear brake pad 2
4 Brake pad shim 4
5 Brake pad support 2
6 Brake caliper piston 2
7 Brake caliper piston dust seal 2
8 Brake caliper piston seal 2
9 Bleed screw 1
10 Brake caliper body 1
For assembly, reverse the disassembly pro-
cedure.

4-36
 REAR BRAKE

EAS22560

INTRODUCTION Brake disc thickness limit

EWA14101
4.5 mm (0.18 in)
WARNING
Disc brake components rarely require disas- 5. Adjust:
sembly. Therefore, always follow these pre- • Brake disc deflection
ventive measures: Refer to “CHECKING THE FRONT BRAKE
• Never disassemble brake components un- DISC” on page 4-22.
less absolutely necessary.
• If any connection on the hydraulic brake Rear brake disc bolt
system is disconnected, the entire brake 23 Nm (2.3 m·kgf, 17 ft·lbf)

T.
R.
system must be disassembled, drained, LOCTITE®
cleaned, properly filled, and bled after reas-
sembly. 6. Install:
• Never use solvents on internal brake com- • Rear wheel
ponents. Refer to “REAR WHEEL” on page 4-15.
• Use only clean or new brake fluid for clean- EAS37P1131

ing brake components. REPLACING THE REAR BRAKE PADS

• Brake fluid may damage painted surfaces (YP125R)
and plastic parts. Therefore, always clean TIP
up any spilt brake fluid immediately. When replacing the brake pads, it is not neces-
• Avoid brake fluid coming into contact with sary to disconnect the brake hose or disassem-
the eyes as it can cause serious injury. ble the brake caliper.
FIRST AID FOR BRAKE FLUID ENTERING
THE EYES: 1. Measure:
• Flush with water for 15 minutes and get im- • Brake pad wear limit “a”
mediate medical attention. Out of specification → Replace the brake
pads as a set.
EAS22570

CHECKING THE REAR BRAKE DISC Brake pad lining thickness (in-
1. Remove: ner)
7.3 mm (0.29 in)
• Rear wheel
Limit
Refer to “REAR WHEEL” on page 4-15.
0.8 mm (0.03 in)
2. Check: Brake pad lining thickness (out-
• Brake disc er)
Damage/galling → Replace. 7.3 mm (0.29 in)
3. Measure: Limit
• Brake disc deflection 0.8 mm (0.03 in)
Out of specification → Correct the brake disc
deflection or replace the brake disc.
Refer to “CHECKING THE FRONT BRAKE
DISC” on page 4-22.

Brake disc deflection limit

0.25 mm (0.0098 in) (YP125R) a
0.15 mm (0.0059 in) (YP250R)

4. Measure:
• Brake disc thickness
Measure the brake disc thickness at a few dif-
2. Install:
ferent locations.
Out of specification → Replace. • Brake pad spring New
Refer to “CHECKING THE FRONT BRAKE • Brake pads New
DISC” on page 4-22.

4-37
 REAR BRAKE

TIP 5. Check:
Always install new brake pads and a new brake • Brake lever operation
pad spring as a set. Soft or spongy feeling → Bleed the brake sys-
tem.
▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼ Refer to “BLEEDING THE HYDRAULIC
a. Connect a clear plastic hose “1” tightly to the
BRAKE SYSTEM” on page 3-36.
bleed screw “2”. Put the other end of the hose
into an open container. EAS22580

b. Loosen the bleed screw and push the brake REPLACING THE REAR BRAKE PADS
caliper pistons into the brake caliper with your (YP250R)
finger. TIP
When replacing the brake pads, it is not neces-
sary to disconnect the brake hose or disassem-
ble the brake caliper.
1. Measure:
• Brake pad wear limit “a”
Out of specification → Replace the brake
pads as a set.
1 2
Brake pad lining thickness (in-
ner)
c. Tighten the bleed screw. 5.3 mm (0.21 in)
Limit
Bleed screw 0.8 mm (0.03 in)
14 Nm (1.4 m·kgf, 10 ft·lbf) Brake pad lining thickness (out-
T.
R.

er)
d. Install new brake pad spring and new brake 5.3 mm (0.21 in)
pads. Limit
▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲ 0.8 mm (0.03 in)
3. Install:
• Brake pad pin
• Brake pad clip New
• Rear brake caliper
• Rear brake caliper bolts
a
Rear brake caliper bolt
40 Nm (4.0 m·kgf, 29 ft·lbf)
T.
R.

4. Check:
• Brake fluid level
Below the minimum level mark “a” → Add the 2. Install:
recommended brake fluid to the proper level. • Brake pad supports New
Refer to “CHECKING THE BRAKE FLUID • Brake pad shims New
LEVEL” on page 3-35. (onto the brake pads)
• Brake pads New
TIP
MIN
a Always install new brake pads, brake pad shims,
MIN
and brake pad supports as a set.
▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼
a. Connect a clear plastic hose “1” tightly to the
bleed screw “2”. Put the other end of the hose
into an open container.

4-38
 REAR BRAKE

b. Loosen the bleed screw and push the brake EAS22590

REMOVING THE REAR BRAKE CALIPER

caliper pistons into the brake caliper with your
finger. TIP
Before removing the brake caliper, drain the
brake fluid from the entire brake system.
1. Remove:
• Brake hose union bolt “1”
2 • Copper washers “2”
1 • Rear brake hose “3”
TIP
Put the end of the brake hose into a container
and pump out the brake fluid carefully.
c. Tighten the bleed screw.
A 2
Bleed screw
6 Nm (0.6 m·kgf, 4.3 ft·lbf)
T.
R.

d. Install new brake pad shims onto each new

brake pad.
e. Install new brake pad supports and new 3
brake pads. 1
▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲
3. Install: B
• Rear brake caliper 1
• Rear brake caliper retaining bolts 3

Rear brake caliper retaining bolt

27 Nm (2.7 m·kgf, 19 ft·lbf)
T.
R.

2
4. Check:
• Brake fluid level
Below the minimum level mark “a” → Add the
recommended brake fluid to the proper level.
A. YP125R
Refer to “CHECKING THE BRAKE FLUID
B. YP250R
LEVEL” on page 3-35.
EAS22610

DISASSEMBLING THE REAR BRAKE

CALIPER (YP250R only)
MIN
a 1. Remove:
• Brake caliper pistons “1”
MIN
• Brake caliper piston dust seals “2”
• Brake caliper piston seals “3”

5. Check:
• Brake lever operation 1 1
Soft or spongy feeling → Bleed the brake sys-
tem. 2 3 2
Refer to “BLEEDING THE HYDRAULIC 3
BRAKE SYSTEM” on page 3-36.

4-39
 REAR BRAKE

▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼
a. Blow compressed air into the brake hose joint
2
opening “a” to force out the pistons from the
brake caliper.
EWA13550 1
WARNING
• Cover the brake caliper piston with a rag.
Be careful not to get injured when the pis-
ton is expelled from the brake caliper.
• Never try to pry out the brake caliper pis-
ton.
EAS22640

CHECKING THE REAR BRAKE CALIPER

a (YP250R)
Recommended brake component replace-
ment schedule
Brake pads If necessary
Piston seals Every two years
Piston dust seals Every two years
Brake hose Every four years
b. Remove the brake caliper piston dust seals Every two years and
and brake caliper piston seals. Brake fluid whenever the brake
▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲
is disassembled
EAS37P1132
1. Check:
CHECKING THE REAR BRAKE CALIPER • Brake caliper pistons “1”
(YP125R) Rust/scratches/wear → Replace the brake
Recommended brake component replace- caliper pistons.
ment schedule • Brake caliper cylinders “2”
Brake pads If necessary Scratches/wear → Replace the brake caliper
assembly.
Brake hose Every four years • Brake caliper body “3”
Every two years and Cracks/damage → Replace the brake caliper
Brake fluid whenever the brake assembly.
is disassembled • Brake fluid delivery passages
(brake caliper body)
1. Check:
Obstruction → Blow out with compressed air.
• Brake caliper pistons “1” EWA37P1014

Rust/scratches/wear → Replace the brake WARNING

caliper assembly. Whenever a brake caliper is disassembled,
• Brake caliper body “2” replace the brake caliper piston dust seals
Cracks/damage → Replace the brake caliper and brake caliper piston seals.
assembly.
• Brake fluid delivery passages
(brake caliper body)
Obstruction → Blow out with compressed air.

4-40
 REAR BRAKE

2. Check: ECA37P1051

• Brake caliper bracket NOTICE

Cracks/damage → Replace. While holding the brake hose, tighten the
union bolt within the angle range shown in
EAS22650
the illustration.
ASSEMBLING THE REAR BRAKE CALIPER
EWA37P1015

WARNING
• Before installation, all internal brake com-
ponents should be cleaned and lubricated
with clean or new brake fluid.
• Never use solvents on internal brake com-
ponents as they will cause the brake caliper 33˚ – 37˚
piston dust seals and brake caliper piston
seals to swell and distort (YP250R only).
• Whenever a brake caliper is disassembled,
replace the brake caliper piston dust seals 2. Remove:
and brake caliper piston seals (YP250R • Rear brake caliper
only). 3. Install:
• Brake pad spring
Recommended fluid • Brake pads
DOT 4 • Brake pad pin
• Brake pad clip New
EAS37P1133

INSTALLING THE REAR BRAKE CALIPER • Rear brake caliper

(YP125R)
Rear brake caliper bolt
1. Install: 40 Nm (4.0 m·kgf, 29 ft·lbf)
T.

• Rear brake caliper “1”

R.

(temporarily) Refer to “REPLACING THE REAR BRAKE

• Copper washers “2” New PADS (YP125R)” on page 4-37.
• Rear brake hose “3” 4. Fill:
• Brake hose union bolt “4” • Brake master cylinder reservoir
(with the specified amount of the recom-
Brake hose union bolt mended brake fluid)
28 Nm (2.8 m·kgf, 20 ft·lbf)
T.
R.

Recommended fluid
DOT 4
2 New
EWA13540

WARNING
• Use only the designated brake fluid. Other
1
brake fluids may cause the rubber seals to
deteriorate, causing leakage and poor
3 brake performance.
4 • Refill with the same type of brake fluid that
is already in the system. Mixing brake fluids
EWA37P1025 may result in a harmful chemical reaction,
WARNING leading to poor brake performance.
Proper brake hose routing is essential to in- • When refilling, be careful that water does
sure safe vehicle operation. Refer to “CABLE not enter the brake master cylinder reser-
ROUTING (YP125R)” on page 2-29. voir. Water will significantly lower the boil-
ing point of the brake fluid and could cause
vapor lock.

4-41
 REAR BRAKE

ECA13540

NOTICE
4
Brake fluid may damage painted surfaces 3
and plastic parts. Therefore, always clean up
any spilt brake fluid immediately.
5. Bleed:
New 2
• Brake system
Refer to “BLEEDING THE HYDRAULIC
BRAKE SYSTEM” on page 3-36.
1
6. Check:
EWA13530
• Brake fluid level
WARNING
Below the minimum level mark “a” → Add the
recommended brake fluid to the proper level. Proper brake hose routing is essential to in-
Refer to “CHECKING THE BRAKE FLUID sure safe vehicle operation. Refer to “CABLE
LEVEL” on page 3-35. ROUTING (YP250R)” on page 2-75.
ECA14170

NOTICE
When installing the brake hose onto the
MIN
a brake caliper “1”, make sure the brake pipe
MIN
“a” touches the projection “b” on the brake
caliper.

a
7. Check:
• Brake lever operation
Soft or spongy feeling → Bleed the brake sys-
tem.
Refer to “BLEEDING THE HYDRAULIC
BRAKE SYSTEM” on page 3-36. 1 b
EAS22670 2. Remove:
INSTALLING THE REAR BRAKE CALIPER • Rear brake caliper
(YP250R) 3. Install:
1. Install: • Brake pad supports
• Rear brake caliper “1” • Brake pad shims
(temporarily) • Brake pads
• Copper washers “2” New • Rear brake caliper
• Rear brake hose “3”
Rear brake caliper bolt
• Brake hose union bolt “4” 40 Nm (4.0 m·kgf, 29 ft·lbf)
T.
R.

Rear brake caliper retaining bolt

Rear brake hose union bolt
27 Nm (2.7 m·kgf, 19 ft·lbf)
23 Nm (2.3 m·kgf, 17 ft·lbf)
T.
R.

Refer to “REPLACING THE REAR BRAKE

PADS (YP250R)” on page 4-38.
4. Fill:
• Brake master cylinder reservoir
(with the specified amount of the recom-
mended brake fluid)

Recommended fluid
DOT 4

4-42
 REAR BRAKE

EWA13540 EAS22700

WARNING REMOVING THE REAR BRAKE MASTER

• Use only the designated brake fluid. Other CYLINDER
brake fluids may cause the rubber seals to TIP
deteriorate, causing leakage and poor Before removing the rear brake master cylinder,
brake performance. drain the brake fluid from the entire brake sys-
• Refill with the same type of brake fluid that tem.
is already in the system. Mixing brake fluids
1. Remove:
may result in a harmful chemical reaction,
• Brake hose union bolt “1”
leading to poor brake performance.
• Copper washers “2”
• When refilling, be careful that water does
• Brake hose “3”
not enter the brake master cylinder reser-
voir. Water will significantly lower the boil- TIP
ing point of the brake fluid and could cause To collect any remaining brake fluid, place a
vapor lock. container under the master cylinder and the end
ECA13540
of the brake hose.
NOTICE
Brake fluid may damage painted surfaces
and plastic parts. Therefore, always clean up
any spilt brake fluid immediately.
5. Bleed:
• Brake system 2
Refer to “BLEEDING THE HYDRAULIC
BRAKE SYSTEM” on page 3-36.
6. Check: 3 1
• Brake fluid level
Below the minimum level mark “a” → Add the EAS22710

CHECKING THE REAR BRAKE MASTER

recommended brake fluid to the proper level.
CYLINDER
Refer to “CHECKING THE BRAKE FLUID
1. Check:
LEVEL” on page 3-35.
• Brake master cylinder
Damage/scratches/wear → Replace.
• Brake fluid delivery passages
MIN
(brake master cylinder body)
a Obstruction → Blow out with compressed air.
MIN
2. Check:
• Brake master cylinder kit
Damage/scratches/wear → Replace.
3. Check:
• Brake master cylinder reservoir cap
• Brake master cylinder reservoir diaphragm
7. Check: holder
• Brake lever operation • Brake master cylinder reservoir diaphragm
Soft or spongy feeling → Bleed the brake sys- Damage/wear → Replace.
tem. 4. Check:
Refer to “BLEEDING THE HYDRAULIC • Rear brake hose
BRAKE SYSTEM” on page 3-36. Cracks/damage/wear → Replace.

4-43
 REAR BRAKE

EAS22730 ECA14160

ASSEMBLING THE REAR BRAKE MASTER NOTICE

CYLINDER When installing the brake hose onto the
EWA13520

WARNING brake master cylinder, make sure the brake

pipe touches the projection “a” as shown.
• Before installation, all internal brake com-
ponents should be cleaned and lubricated TIP
with clean or new brake fluid. Turn the handlebar to the left and right to make
• Never use solvents on internal brake com- sure the brake hose does not touch other parts
ponents. (e.g., wire harness, cables, leads). Correct if
necessary.
Recommended fluid
DOT 4

EAS22750

INSTALLING THE REAR BRAKE MASTER

CYLINDER
1. Install: 1 New
• Brake master cylinder “1”
• Brake master cylinder holder
2 3 a
Brake master cylinder holder bolt
7 Nm (0.7 m·kgf, 5.1 ft·lbf) 3. Fill:
T.
R.

• Brake master cylinder reservoir

TIP (with the specified amount of the recom-
• Align the projection “a” on the brake master cyl- mended brake fluid)
inder with the hole “b” in the handlebar.
• First, tighten the front bolt, then the rear bolt. Recommended fluid
DOT 4
1 b EWA13540

WARNING
• Use only the designated brake fluid. Other
brake fluids may cause the rubber seals to
deteriorate, causing leakage and poor
a brake performance.
• Refill with the same type of brake fluid that
is already in the system. Mixing brake fluids
may result in a harmful chemical reaction,
2. Install: leading to poor brake performance.
• When refilling, be careful that water does
• Copper washers “1” New
not enter the brake master cylinder reser-
• Rear brake hose “2”
voir. Water will significantly lower the boil-
• Brake hose union bolt “3”
ing point of the brake fluid and could cause
Brake hose union bolt vapor lock.
23 Nm (2.3 m·kgf, 17 ft·lbf) ECA13540
T.
R.

NOTICE
EWA37P1024

WARNING Brake fluid may damage painted surfaces

and plastic parts. Therefore, always clean up
Proper brake hose routing is essential to in-
any spilt brake fluid immediately.
sure safe vehicle operation. Refer to “CABLE
ROUTING (YP125R)” on page 2-29 and “CA- 4. Bleed:
BLE ROUTING (YP250R)” on page 2-75. • Brake system
Refer to “BLEEDING THE HYDRAULIC
BRAKE SYSTEM” on page 3-36.

4-44
 REAR BRAKE

5. Check:
• Brake fluid level
Below the minimum level mark “a” → Add the
recommended brake fluid to the proper level.
Refer to “CHECKING THE BRAKE FLUID
LEVEL” on page 3-35.

MIN
a
MIN

6. Check:
• Brake lever operation
Soft or spongy feeling → Bleed the brake sys-
tem.
Refer to “BLEEDING THE HYDRAULIC
BRAKE SYSTEM” on page 3-36.

4-45
 HANDLEBAR

EAS22840

HANDLEBAR
Removing the handlebar

7 Nm (0.7 m•kgf, 5.1 ft•Ibf)

T.R
.
3
23 Nm (2.3 m•kgf, 17 ft•Ibf)
T.R
.

4
7 Nm (0.7 m•kgf, 5.1 ft•Ibf)
T.R
.

13 5
10
7 1
2

14
LS
8 5
6
LS

6
26 Nm (2.6 m•kgf, 19 ft•Ibf)

T.R
.
11

12
1

26 Nm (2.6 m•kgf, 19 ft•Ibf)

T.R
.

Order Job/Parts to remove Q’ty Remarks

Refer to “GENERAL CHASSIS” on page
Lower handlebar cover 4-1.
1 Grip end 2
2 Front brake light switch connector 2 Disconnect.
3 Front brake master cylinder holder 1
4 Front brake master cylinder 1
5 Right handlebar switch 1
6 Throttle cable 2 Disconnect.
7 Throttle grip 1
8 Rear brake light switch connector 2 Disconnect.
9 Rear brake master cylinder holder 1
10 Rear brake master cylinder 1
11 Left handlebar switch 1
12 Handlebar grip 1
13 Upper handlebar holder 2

4-46
 HANDLEBAR

Removing the handlebar

7 Nm (0.7 m•kgf, 5.1 ft•Ibf)

T.R
.
3
23 Nm (2.3 m•kgf, 17 ft•Ibf)
T.R
.

4
7 Nm (0.7 m•kgf, 5.1 ft•Ibf)
T.R
.

13 5
10
7 1
2

14
LS
8 5
6
LS

6
26 Nm (2.6 m•kgf, 19 ft•Ibf)

T.R
.
11

12
1

26 Nm (2.6 m•kgf, 19 ft•Ibf)

T.R
.

Order Job/Parts to remove Q’ty Remarks

14 Handlebar 1
For installation, reverse the removal proce-
dure.

4-47
 HANDLEBAR

EAS22860

REMOVING THE HANDLEBAR TIP

1. Stand the vehicle on a level surface. The upper handlebar holders should be installed
EWA13120 with the arrow marks “a” facing forward “A”.
WARNING
Securely support the vehicle so that there is
no danger of it falling over.
2. Remove:
• Handlebar grip “1”
TIP
Blow compressed air between the handlebar
and the handlebar grip, and gradually push the
grip off the handlebar.
3. Install:
• Handlebar grip
▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼
a. Apply a thin coat of a rubber adhesive to the
left end of the handlebar.
b. Slide the handlebar grip over the left end of
the handlebar.
c. Wipe off any excess rubber adhesive with a
clean rag.
EWA13700

WARNING
EAS22880

CHECKING THE HANDLEBAR Do not touch the handlebar grip until the rub-
1. Check: ber adhesive has fully dried.
• Handlebar
▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲
Bends/cracks/damage → Replace.
EWA13690 4. Install:
WARNING • Left handlebar switch “1”
Do not attempt to straighten a bent handle- TIP
bar as this may dangerously weaken it. Align the projection “a” on the left handlebar
switch with the hole “b” in the handlebar.
EAS22920

INSTALLING THE HANDLEBAR

1. Stand the vehicle on a level surface. 1
EWA13120

WARNING
a
Securely support the vehicle so that there is
no danger of it falling over.
2. Install: b
• Handlebar
• Upper handlebar holders

Upper handlebar holder bolt 5. Install:

23 Nm (2.3 m·kgf, 17 ft·lbf) • Rear brake master cylinder “1”
T.
R.

• Rear brake master cylinder holder

ECA37P1031

NOTICE Brake master cylinder holder bolt

First, tighten the front bolt on each handle- 7 Nm (0.7 m·kgf, 5.1 ft·lbf)
T.
R.

bar holder, then the rear bolt.

4-48
 HANDLEBAR

TIP
b 1
• Align the projection “a” on the brake master cyl-
inder with the hole “b” in the handlebar.
• First, tighten the front bolt, then the rear bolt.

1 b
a

8. Adjust:
a
• Throttle cable free play
Refer to “ADJUSTING THE THROTTLE CA-
BLE FREE PLAY” on page 3-23.

6. Install: Throttle cable free play

• Throttle grip “1” 3.0–5.0 mm (0.12–0.20 in)
• Throttle cables “2”
• Right handlebar switch “3”
TIP
• Be sure to position the washer between the
throttle grip and the right handlebar switch.
• Lubricate the end of the throttle cables and the
inside of the throttle grip with a thin coat of lith-
ium-soap-based grease.
• Align the projection “a” on the right handlebar
switch with the hole “b” in the handlebar.
• Be sure to slide the throttle cable rubber cover
to its original position.

a 1
2
b
3

7. Install:
• Front brake master cylinder “1”
• Front brake master cylinder holder

Brake master cylinder holder bolt

7 Nm (0.7 m·kgf, 5.1 ft·lbf)
T.
R.

TIP
• Align the projection “a” on the brake master cyl-
inder with the hole “b” in the handlebar.
• First, tighten the front bolt, then the rear bolt.

4-49
 FRONT FORK

EAS22950

FRONT FORK
Removing the front fork legs

45 Nm (4.5 m•kgf, 32 ft•Ibf)

T.R
.
3

New
LT
LT

23 Nm (2.3 m•kgf, 17 ft•Ibf)

T.R
.

7 Nm (0.7 m•kgf, 5.1 ft•Ibf) 4

T.R
.

LT
LT LT

2
1 LT
LT
7 Nm (0.7 m•kgf, 5.1 ft•Ibf)

T.R
.
7 Nm (0.7 m•kgf, 5.1 ft•Ibf)
T.R
.

40 Nm (4.0 m•kgf, 29 ft•Ibf)

T.R
.

Order Job/Parts to remove Q’ty Remarks

The following procedure applies to both of
the front fork legs.
Refer to “GENERAL CHASSIS” on page
Front cowling assembly 4-1.
Front wheel Refer to “FRONT WHEEL” on page 4-9.
1 Front brake caliper 1
2 Front fender 1
3 Cap bolt 1
4 Lower bracket pinch bolt 2 Loosen.
5 Front fork leg 1
For installation, reverse the removal proce-
dure.

4-50
 FRONT FORK

Disassembling the front fork legs

New 2

New 3

New 9 1

10

6
New 5
8
4

LT

30 Nm (3.0 m•kgf, 22 ft•Ibf)

T.R
.

Order Job/Parts to remove Q’ty Remarks

The following procedure applies to both of
the front fork legs.
1 Fork spring 1
2 Dust seal 1
3 Oil seal clip 1
4 Damper rod bolt 1
5 Copper washer 1
6 Damper rod 1
7 Inner tube 1
8 Oil flow stopper 1
9 Oil seal 1
10 Outer tube 1
For assembly, reverse the disassembly pro-
cedure.

4-51
 FRONT FORK

EAS22960

REMOVING THE FRONT FORK LEGS

The following procedure applies to both of the
front fork legs.
1. Stand the vehicle on a level surface.
EWA13120

WARNING
Securely support the vehicle so that there is
no danger of it falling over.
2. Remove:
• Cap bolt “1” 2. Remove:
ECA37P1027
• Dust seal “1”
NOTICE
• Oil seal clip “2”
When removing the cap bolt, take care not to (with a flat-head screwdriver)
damage the rectifier/regulator “2” with the ECA14180

tools. NOTICE

TIP Do not scratch the inner tube.

If the cap bolt is difficult to loosen, slightly loosen
the lower bracket pinch bolts “3”.
1
3. Loosen:
• Lower bracket pinch bolts
EWA37P1022

WARNING 2
Before loosening the lower bracket pinch
bolts, support the front fork leg.

3. Remove:
• Damper rod bolt “1”
2 • Copper washer
• Damper rod
3 TIP
While holding the damper rod with the damper
1 rod holder “2” and T-handle “3”, loosen the
damper rod bolt.
EAS22980

DISASSEMBLING THE FRONT FORK LEGS Damper rod holder

The following procedure applies to both of the 90890-01294
front fork legs. Damping rod holder set
YM-01300
1. Drain:
T-handle
• Fork oil 90890-01326
TIP T-handle 3/8" drive 60 cm long
Stroke the inner tube several times while drain- YM-01326
ing the fork oil.

4-52
 FRONT FORK

EAS23030

1 ASSEMBLING THE FRONT FORK LEGS

The following procedure applies to both of the
2 front fork legs.
EWA13660

WARNING
• Make sure the oil levels in both front fork
3 legs are equal.
• Uneven oil levels can result in poor han-
dling and a loss of stability.
EAS23010 TIP
CHECKING THE FRONT FORK LEGS • When assembling the front fork leg, be sure to
The following procedure applies to both of the replace the following parts:
front fork legs. –Oil seal
1. Check: –Dust seal
• Inner tube –Clip
• Outer tube • Before assembling the front fork leg, make
Bends/damage/scratches → Replace. sure all of the components are clean.
EWA13650

WARNING 1. Install:
Do not attempt to straighten a bent inner • Damper rod “1”
ECA37P1033
tube as this may dangerously weaken it.
NOTICE
2. Measure: Allow the damper rod to slide slowly down
• Spring free length “a” the inner tube “2” until it protrudes from the
Out of specification → Replace. bottom of the inner tube. Be careful not to
damage the inner tube.
Fork spring free length
340.0 mm (13.39 in)
Limit
333.0 mm (13.11 in) 1 2

2. Lubricate:
• Inner tube’s outer surface

Recommended oil
3. Check: Fork oil 10W or equivalent
• Damper rod
Damage/wear → Replace. 3. Tighten:
Obstruction → Blow out all of the oil passag- • Damper rod bolt “1”
es with compressed air.
• Oil flow stopper Damper rod bolt
Damage → Replace. 30 Nm (3.0 m·kgf, 22 ft·lbf)
T.
R.

ECA37P1032 LOCTITE®
NOTICE
When disassembling and assembling the
front fork leg, do not allow any foreign mate-
rial to enter the front fork.

4-53
 FRONT FORK

TIP
While holding the damper rod with the damper
rod holder “2” and T-handle “3”, tighten the
damper rod bolt.

Damper rod holder

90890-01294
Damping rod holder set
YM-01300
T-handle
90890-01326
T-handle 3/8" drive 60 cm long
YM-01326

5. Install:
3
• Oil seal clip “1”
TIP
4. Install: Adjust the oil seal clip so that it fits into the outer
tube’s groove.
• Oil seal “1” New
(with the fork seal driver weight “2” and fork
seal driver attachment “3”)

Fork seal driver weight

90890-01367
Replacement hammer
YM-A9409-7
Fork seal driver attachment (ø38)
90890-01372
Replacement 38 mm
YM-A5142-1
6. Install:
ECA14220
• Dust seal “1” New
NOTICE
(with the fork seal driver weight “2”)
Make sure the numbered side of the oil seal
faces up. Fork seal driver weight
90890-01367
TIP Replacement hammer
• Before installing the oil seal, lubricate its lips YM-A9409-7
with lithium-soap-based grease.
• Lubricate the outer surface of the inner tube
with fork oil.
• Before installing the oil seal, cover the top of
the front fork leg with a plastic bag to protect
the oil seal during installation.

4-54
 FRONT FORK

10.Measure:
• Front fork leg oil level “a”
(from the top of the inner tube, with the inner
tube fully compressed and without the fork
spring)
Out of specification → Correct.

Level
109.0 mm (4.29 in)

7. Fill:
• Front fork leg
(with the specified amount of the recom-
mended fork oil)

Recommended oil
Fork oil 10W or equivalent
Quantity
128.0 cm³ (4.33 US oz, 4.51
Imp.oz)
ECA14230 11.Install:
NOTICE • Fork spring
• Be sure to use the recommended fork oil. EAS23050
Other oils may have an adverse effect on INSTALLING THE FRONT FORK LEGS
front fork performance. The following procedure applies to both of the
• When disassembling and assembling the front fork legs.
front fork leg, do not allow any foreign ma- 1. Install:
terial to enter the front fork. • Front fork leg “1”
EWA37P1023
8. After filling the front fork leg, slowly stroke the WARNING
inner tube “1” up and down (at least ten
Make sure the brake hose is routed properly.
times) to distribute the fork oil.
TIP TIP
Be sure to stroke the inner tube slowly because Pull up the inner tube until it stops, and then
the fork oil may spurt out. tighten the lower bracket pinch bolts.

Lower bracket pinch bolt

23 Nm (2.3 m·kgf, 17 ft·lbf)
T.
R.

2
9. Before measuring the fork oil level, wait ten
minutes until the oil has settled and the air
bubbles have dispersed. 1
TIP
2. Lower bracket
Be sure to bleed the front fork leg of any residual
air.

4-55
 FRONT FORK

2. Install:
• Cap bolt
(along with the O-ring New )

Cap bolt
45 Nm (4.5 m·kgf, 32 ft·lbf)
T.
R.

ECA37P1028

NOTICE
When installing the cap bolt, take care not to
damage the rectifier/regulator with the tools.
TIP
• Before installing the cap bolt, lubricate its O-
ring with grease.
• If the cap bolt is difficult to install, slightly loos-
en the lower bracket pinch bolts.

4-56
 STEERING HEAD

EAS23090

STEERING HEAD
Removing the lower bracket

120 Nm (12.0 m•kgf, 85 ft•lbf) 2

T.R
.

3
75 Nm (7.5 m•kgf, 54 ft•Ibf)
T.R
.

LS
17
1st 38 Nm (3.8 m•kgf, 27 ft•lbf) 14
5
T.R

2nd 22 Nm (2.2 m•kgf, 16 ft•lbf)

.

6 15
7 16
8
LS 9
11
10 4
12
13
18

9 Nm (0.9 m•kgf, 6.5 ft•Ibf)

T.R
.

Order Job/Parts to remove Q’ty Remarks

Refer to “GENERAL CHASSIS” on page
Front cowling assembly 4-1.
Refer to “GENERAL CHASSIS” on page
Meter assembly cover 4-1.
Front fork legs Refer to “FRONT FORK” on page 4-50.
1 Speed sensor lead holder bracket 1
2 Steering stem nut 1
3 Lower handlebar holder 1
4 Woodruff key 1
5 Upper ring nut 1
6 Lock washer 1
7 Center ring nut 1
8 Rubber washer 1
9 Lower ring nut 1
10 Lower bracket 1
11 Upper bearing cover 1
12 Upper bearing inner race 1

4-57
 STEERING HEAD

Removing the lower bracket

120 Nm (12.0 m•kgf, 85 ft•lbf) 2

T.R
.

3
75 Nm (7.5 m•kgf, 54 ft•Ibf)
T.R
.

LS
17
1st 38 Nm (3.8 m•kgf, 27 ft•lbf) 14
5
T.R

2nd 22 Nm (2.2 m•kgf, 16 ft•lbf)

.

6 15
7 16
8
LS 9
11
10 4
12
13
18

9 Nm (0.9 m•kgf, 6.5 ft•Ibf)

T.R
.

Order Job/Parts to remove Q’ty Remarks

13 Upper bearing 1
14 Lower bearing 1
15 Lower bearing inner race 1
16 Dust seal 1
17 Lower bearing outer race 1
18 Upper bearing outer race 1
For installation, reverse the removal proce-
dure.

4-58
 STEERING HEAD

EAS23110
▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼
REMOVING THE LOWER BRACKET a. Remove the bearing races from the steering
1. Stand the vehicle on a level surface. head pipe “1” with a long rod “2” and hammer.
EWA13120
b. Remove the bearing race from the lower
WARNING
bracket “3” with a floor chisel “4” and ham-
Securely support the vehicle so that there is mer.
no danger of it falling over. c. Install new bearing races.
ECA14270
2. Remove:
NOTICE
• Upper ring nut “1”
• Lock washer If the bearing race is not installed properly,
• Center ring nut the steering head pipe could be damaged.
• Rubber washer TIP
• Lower ring nut “2”
Always replace the bearings and bearing races
• Lower bracket
EWA13730 as a set.
WARNING
Securely support the lower bracket so that
there is no danger of it falling.
TIP
Remove the upper ring nut and lower ring nut
with the steering nut wrench “3”.

Steering nut wrench

90890-01403
Exhaust flange nut wrench
YU-A9472

1 ▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲
2 4. Check:
EAS23120 • Lower handlebar holder
CHECKING THE STEERING HEAD • Lower bracket
1. Wash: (along with the steering stem)
• Bearings Bends/cracks/damage → Replace.
• Bearing races
EAS23150

Recommended cleaning solvent INSTALLING THE STEERING HEAD

Kerosene 1. Lubricate:
• Upper bearing
2. Check: • Lower bearing
• Bearings • Bearing races
• Bearing races
Recommended lubricant
Damage/pitting → Replace.
Lithium-soap-based grease
3. Replace:
• Bearings 2. Install:
• Bearing races • Lower ring nut “1”

4-59
 STEERING HEAD

• Rubber washer
• Center ring nut “2”
• Lock washer “3”
• Upper ring nut “4”
Refer to “CHECKING AND ADJUSTING
THE STEERING HEAD” on page 3-37.

3. Install:
• Woodruff key “1”
• Lower handlebar holder “2”
• Steering stem nut

Steering stem nut

120 Nm (12.0 m·kgf, 85 ft·lbf)
T.
R.

TIP
Align the woodruff key with the groove “a” in the
lower handlebar holder.

2
1

4-60
 REAR SHOCK ABSORBER ASSEMBLIES AND SWINGARM

EAS23160

REAR SHOCK ABSORBER ASSEMBLIES AND SWINGARM

Removing the rear shock absorber assemblies and swingarm (YP125R)

2
3

LS

7
New 8
LS
9
5
9
New 8
LS 6
1
135 Nm (13.5 m•kgf, 98 ft•lbf)
T.R

4
.

40 Nm (4.0 m•kgf, 29 ft•Ibf)

T.R
.

7 Nm (0.7 m•kgf, 5.1 ft•Ibf)

T.R
.

32 Nm (3.2 m•kgf, 23 ft•Ibf) 28 Nm (2.8 m•kgf, 20 ft•Ibf)

T.R

T.R
.

18 Nm (1.8 m•kgf, 13 ft•Ibf) 7 Nm (0.7 m•kgf, 5.1 ft•Ibf)

T.R
.
T.R
.

Order Job/Parts to remove Q’ty Remarks

Refer to “ENGINE REMOVAL (YP125R)” on
Muffler page 5-1.
1 Rear wheel axle nut 1
2 Brake hose holder 1
3 Rear brake caliper 1
4 Rear shock absorber assembly 2
5 Swingarm 1
6 Spacer 1
7 Collar 1
8 Oil seal 2
9 Bearing 2
For installation, reverse the removal proce-
dure.

4-61
 REAR SHOCK ABSORBER ASSEMBLIES AND SWINGARM

Removing the rear shock absorber assemblies and swingarm (YP250R)

7 Nm (0.7 m•kgf, 5.1 ft•Ibf)

T.R
.
2
3

LT

7
4 New 8
LS

5
4 11
New 10
New 9
6
LS 1
135 Nm (13.5 m•kgf, 98 ft•lbf)
T.R
.

18 Nm (1.8 m•kgf, 13 ft•Ibf) 40 Nm (4.0 m•kgf, 29 ft•Ibf)

T.R

T.R
.

32 Nm (3.2 m•kgf, 23 ft•Ibf) 59 Nm (5.9 m•kgf, 43 ft•Ibf)

T.R

T.R
.

Order Job/Parts to remove Q’ty Remarks

Refer to “ENGINE REMOVAL (YP250R)” on
Muffler page 5-61.
1 Rear wheel axle nut 1
2 Brake hose holder 1
3 Rear brake caliper 1
4 Rear shock absorber assembly 2
5 Swingarm 1
6 Spacer 1
7 Collar 1
8 Oil seal 1
9 Oil seal 1
10 Circlip 1
11 Bearing 1
For installation, reverse the removal proce-
dure.

4-62
 REAR SHOCK ABSORBER ASSEMBLIES AND SWINGARM

EAS23220
3. Remove:
REMOVING THE REAR SHOCK ABSORBER
• Swingarm
ASSEMBLIES
1. Stand the vehicle on a level surface. EAS23240

EWA13120 CHECKING THE REAR SHOCK ABSORBER

WARNING ASSEMBLY
Securely support the vehicle so that there is 1. Check:
no danger of it falling over. • Rear shock absorber rod
Bends/damage → Replace the rear shock
TIP absorber assembly.
Place the vehicle on the centerstand so that the • Rear shock absorber
rear wheel is elevated. Oil leaks → Replace the rear shock absorber
assembly.
EAS23340
• Spring
REMOVING THE SWINGARM Damage/wear → Replace the rear shock ab-
1. Stand the vehicle on a level surface. sorber assembly.
EWA13120

WARNING • Bushings
Damage/wear → Replace.
Securely support the vehicle so that there is
• Bolts
no danger of it falling over.
Bends/damage/wear → Replace.
TIP
EAS23370
Place the vehicle on the centerstand so that the CHECKING THE SWINGARM
rear wheel is elevated. 1. Check:
2. Remove: • Swingarm
• Rear wheel axle nut “1” Bends/cracks/damage → Replace.
• Brake hose holder “2” 2. Check:
• Rear brake caliper “3” • Spacer
• Rear shock absorber assembly lower bolt “4” • Collar
• Oil seals
TIP
• Bearing
Do not squeeze the brake lever when removing Damage/wear → Replace.
the brake caliper.
EAS28780

A INSTALLING THE SWINGARM

1. Lubricate:
3 2
• Bearing
• Oil seal lips

Recommended lubricant
Lithium-soap-based grease
4
2. Install:
1 • Swingarm “1”
B • Rear wheel axle nut “2”
2 (temporarily tighten)
3 • Swingarm mounting bolt (upper side) “3”
(temporarily tighten)
4 • Swingarm mounting bolt (lower side) “4”
(temporarily tighten)
1 3. Tighten:
• Rear wheel axle nut “2”
• Swingarm mounting bolt (upper side) “3”
• Swingarm mounting bolt (lower side) “4”
A. YP125R
B. YP250R

4-63
 REAR SHOCK ABSORBER ASSEMBLIES AND SWINGARM

Rear wheel axle nut

135 Nm (13.5 m·kgf, 98 ft·lbf)
T.
R.

Swingarm mounting bolt (upper

side)
28 Nm (2.8 m·kgf, 20 ft·lbf)
(YP125R)
59 Nm (5.9 m·kgf, 43 ft·lbf)
(YP250R)
Swingarm mounting bolt (lower
side)
28 Nm (2.8 m·kgf, 20 ft·lbf)
(YP125R)
59 Nm (5.9 m·kgf, 43 ft·lbf)
(YP250R)

1
2
4
B
3
1

4
A. YP125R
B. YP250R

4-64
REAR SHOCK ABSORBER ASSEMBLIES AND SWINGARM

4-65
 ENGINE

ENGINE REMOVAL (YP125R)........................................................................ 5-1

INSTALLING THE ENGINE....................................................................... 5-5

CYLINDER HEAD (YP125R)........................................................................... 5-7

REMOVING THE CYLINDER HEAD......................................................... 5-9
CHECKING THE CYLINDER HEAD ......................................................... 5-9
CHECKING THE CAMSHAFT SPROCKET............................................ 5-10
CHECKING THE TIMING CHAIN TENSIONER...................................... 5-10
INSTALLING THE CYLINDER HEAD ..................................................... 5-11

CAMSHAFT (YP125R) .................................................................................. 5-14

REMOVING THE CAMSHAFT ................................................................ 5-15
CHECKING THE CAMSHAFT................................................................. 5-15
CHECKING THE DECOMPRESSION SYSTEM..................................... 5-15
CHECKING THE ROCKER ARMS AND ROCKER ARM SHAFTS ........ 5-16
INSTALLING THE CAMSHAFT AND ROCKER ARMS .......................... 5-17

VALVES AND VALVE SPRINGS (YP125R) ................................................. 5-18

REMOVING THE VALVES...................................................................... 5-19
CHECKING THE VALVES AND VALVE GUIDES .................................. 5-19
CHECKING THE VALVE SEATS ............................................................ 5-21
CHECKING THE VALVE SPRINGS........................................................ 5-22
INSTALLING THE VALVES .................................................................... 5-23
5
CYLINDER AND PISTON (YP125R)............................................................. 5-25
REMOVING THE PISTON ...................................................................... 5-26
CHECKING THE CYLINDER AND PISTON ........................................... 5-26
CHECKING THE PISTON RINGS........................................................... 5-27
CHECKING THE PISTON PIN ................................................................ 5-28
CHECKING THE TIMING CHAIN GUIDE ............................................... 5-28
INSTALLING THE PISTON AND CYLINDER ......................................... 5-28

V-BELT AUTOMATIC TRANSMISSION (YP125R) ...................................... 5-30

REMOVING THE PRIMARY SHEAVE.................................................... 5-33
REMOVING THE SECONDARY SHEAVE ............................................. 5-33
DISASSEMBLING THE SECONDARY SHEAVE.................................... 5-34
CHECKING THE CLUTCH HOUSING .................................................... 5-34
CHECKING THE CLUTCH SHOES ........................................................ 5-34
CHECKING THE V-BELT........................................................................ 5-34
CHECKING THE PRIMARY SHEAVE .................................................... 5-35
CHECKING THE PRIMARY SHEAVE WEIGHTS................................... 5-35
CHECKING THE PRIMARY SHEAVE SLIDERS .................................... 5-35
CHECKING THE SECONDARY SHEAVE .............................................. 5-35
ASSEMBLING THE PRIMARY SHEAVE ................................................ 5-35
ASSEMBLING THE SECONDARY SHEAVE.......................................... 5-36
INSTALLING THE V-BELT...................................................................... 5-37
STARTER CLUTCH AND GENERATOR (YP125R)..................................... 5-39
REMOVING THE GENERATOR ............................................................. 5-41
REMOVING THE STARTER CLUTCH ................................................... 5-41
CHECKING THE STARTER CLUTCH .................................................... 5-41
INSTALLING THE STARTER CLUTCH .................................................. 5-42
INSTALLING THE GENERATOR............................................................ 5-42

ELECTRIC STARTER (YP125R) .................................................................. 5-44

CHECKING THE STARTER MOTOR ..................................................... 5-46

OIL PUMP (YP125R) ..................................................................................... 5-48

CHECKING THE OIL PUMP ................................................................... 5-49
ASSEMBLING THE OIL PUMP............................................................... 5-49
INSTALLING THE OIL PUMP ................................................................. 5-50

TRANSMISSION (YP125R)........................................................................... 5-51

REMOVING THE TRANSMISSION ........................................................ 5-53
CHECKING THE TRANSMISSION ......................................................... 5-53
INSTALLING THE TRANSMISSION ....................................................... 5-53

CRANKSHAFT (YP125R) ............................................................................. 5-54

DISASSEMBLING THE CRANKCASE.................................................... 5-56
REMOVING THE CRANKSHAFT ASSEMBLY ....................................... 5-56
CHECKING THE TIMING CHAIN AND TIMING CHAIN GUIDE............. 5-56
CHECKING THE CRANKSHAFT AND CONNECTING ROD ................. 5-56
CHECKING THE CRANKCASE .............................................................. 5-57
CHECKING THE BEARING AND OIL SEAL........................................... 5-57
CHECKING THE OIL PUMP DRIVE GEAR ............................................ 5-57
CHECKING THE OIL STRAINERS ......................................................... 5-58
INSTALLING THE CRANKSHAFT .......................................................... 5-58
ASSEMBLING THE CRANKCASE.......................................................... 5-59

ENGINE REMOVAL (YP250R)...................................................................... 5-61

INSTALLING THE ENGINE..................................................................... 5-65

CYLINDER HEAD (YP250R)......................................................................... 5-67

REMOVING THE CYLINDER HEAD....................................................... 5-69
CHECKING THE CYLINDER HEAD ....................................................... 5-69
CHECKING THE CAMSHAFT SPROCKET............................................ 5-70
CHECKING THE TIMING CHAIN TENSIONER...................................... 5-70
INSTALLING THE CYLINDER HEAD ..................................................... 5-71

CAMSHAFT (YP250R) .................................................................................. 5-73

REMOVING THE ROCKER ARMS AND CAMSHAFT............................ 5-74
CHECKING THE CAMSHAFT................................................................. 5-74
CHECKING THE ROCKER ARMS AND ROCKER ARM SHAFTS ........ 5-75
INSTALLING THE CAMSHAFT AND ROCKER ARMS .......................... 5-75
VALVES AND VALVE SPRINGS (YP250R) ................................................. 5-77
REMOVING THE VALVES...................................................................... 5-78
CHECKING THE VALVES AND VALVE GUIDES .................................. 5-78
CHECKING THE VALVE SEATS ............................................................ 5-80
CHECKING THE VALVE SPRINGS........................................................ 5-81
INSTALLING THE VALVES .................................................................... 5-82

CYLINDER AND PISTON (YP250R)............................................................. 5-84

REMOVING THE PISTON ...................................................................... 5-85
CHECKING THE CYLINDER AND PISTON ........................................... 5-85
CHECKING THE PISTON RINGS........................................................... 5-86
CHECKING THE PISTON PIN ................................................................ 5-87
CHECKING THE TIMING CHAIN GUIDE ............................................... 5-87
INSTALLING THE PISTON AND CYLINDER ......................................... 5-87

V-BELT AUTOMATIC TRANSMISSION (YP250R) ...................................... 5-89

REMOVING THE PRIMARY SHEAVE.................................................... 5-93
REMOVING THE SECONDARY SHEAVE ............................................. 5-93
DISASSEMBLING THE SECONDARY SHEAVE.................................... 5-94
CHECKING THE CLUTCH HOUSING .................................................... 5-94
CHECKING THE CLUTCH SHOES ........................................................ 5-94
CHECKING THE V-BELT........................................................................ 5-94
CHECKING THE PRIMARY SHEAVE .................................................... 5-95
CHECKING THE PRIMARY SHEAVE WEIGHTS................................... 5-95
CHECKING THE PRIMARY SHEAVE SLIDERS .................................... 5-95
CHECKING THE SECONDARY SHEAVE .............................................. 5-95
ASSEMBLING THE PRIMARY SHEAVE ................................................ 5-95
ASSEMBLING THE SECONDARY SHEAVE.......................................... 5-96
INSTALLING THE V-BELT...................................................................... 5-97

STARTER CLUTCH AND GENERATOR (YP250R)..................................... 5-99

REMOVING THE GENERATOR ...........................................................5-101
REMOVING THE STARTER CLUTCH .................................................5-101
CHECKING THE STARTER CLUTCH ..................................................5-101
INSTALLING THE STARTER CLUTCH ................................................5-102
INSTALLING THE GENERATOR..........................................................5-102

ELECTRIC STARTER (YP250R) ................................................................ 5-104

CHECKING THE STARTER MOTOR ...................................................5-106
ASSEMBLING THE STARTER MOTOR...............................................5-107

OIL PUMP (YP250R) ...................................................................................5-108

CHECKING THE OIL PUMP .................................................................5-110
ASSEMBLING THE OIL PUMP.............................................................5-110
INSTALLING THE OIL PUMP ...............................................................5-111

TRANSMISSION (YP250R).........................................................................5-112
REMOVING THE TRANSMISSION ...................................................... 5-114
CHECKING THE TRANSMISSION .......................................................5-114
INSTALLING THE TRANSMISSION .....................................................5-114
CRANKSHAFT (YP250R) ........................................................................... 5-115
DISASSEMBLING THE CRANKCASE..................................................5-117
REMOVING THE CRANKSHAFT ASSEMBLY .....................................5-117
CHECKING THE TIMING CHAIN AND TIMING CHAIN GUIDE........... 5-118
CHECKING THE CRANKSHAFT AND CONNECTING ROD ...............5-118
CHECKING THE CRANKCASE ............................................................5-119
CHECKING THE BEARING AND OIL SEAL.........................................5-119
CHECKING THE OIL STRAINERS .......................................................5-119
INSTALLING THE CRANKSHAFT ........................................................5-119
ASSEMBLING THE CRANKCASE........................................................5-120
 ENGINE REMOVAL (YP125R)

EAS37P1135

ENGINE REMOVAL (YP125R)

Removing the muffler and exhaust pipe

3
1

New 6

45 Nm (4.5 m•kgf, 32 ft•Ibf)

T.R
.

5 2

53 Nm (5.3 m•kgf, 38 ft•Ibf)

4 New
T.R
.

14 Nm (1.4 m•kgf, 10 ft•Ibf) 20 Nm (2.0 m•kgf, 14 ft•Ibf)

T.R
T.R

.
.

Order Job/Parts to remove Q’ty Remarks

1 O2 sensor coupler 1 Disconnect.

2 O2 sensor 1

3 Muffler 1
4 Gasket 1
5 Exhaust pipe 1
6 Gasket 1
For installation, reverse the removal proce-
dure.

5-1
 ENGINE REMOVAL (YP125R)

Disconnecting the leads and hoses

7 Nm (0.7 m•kgf, 5.1 ft•Ibf)

T.R
.
3 7
8

4
1
6

Order Job/Parts to remove Q’ty Remarks

Drain.
Engine oil Refer to “CHANGING THE ENGINE OIL” on
page 3-12.
Drain.
Coolant Refer to “CHANGING THE COOLANT” on
page 3-18.
Refer to “GENERAL CHASSIS” on page
Air filter case 4-1.
Refer to “V-BELT AUTOMATIC TRANSMIS-
V-belt case air duct joint SION (YP125R)” on page 5-30.
Fuel injector assembly/Throttle body/Intake Refer to “THROTTLE BODY” on page 7-5.
manifold
1 Spark plug cap 1 Disconnect.
2 Coolant temperature sensor coupler 1 Disconnect.
Crankshaft position sensor/stator assembly
3 2 Disconnect.
coupler
4 Radiator inlet hose 1 Disconnect.
5 Radiator outlet hose 1 Disconnect.
6 Cylinder head breather hose 1
7 Starter motor lead 1 Disconnect.

5-2
 ENGINE REMOVAL (YP125R)

Disconnecting the leads and hoses

7 Nm (0.7 m•kgf, 5.1 ft•Ibf)

T.R
.
3 7
8

4
1
6

Order Job/Parts to remove Q’ty Remarks

8 Ground lead 1 Disconnect.
For installation, reverse the removal proce-
dure.

5-3
 ENGINE REMOVAL (YP125R)

Removing the engine

8 59 Nm (5.9 m•kgf, 43 ft•Ibf)

T.R
.
9
8
5
32 Nm (3.2 m•kgf, 23 ft•Ibf)

T.R
.
43 Nm (4.3 m•kgf, 31 ft•Ibf)
T.R
.

2
3
4
18 Nm (1.8 m•kgf, 13 ft•Ibf)
1

T.R
6

.
5

64 Nm (6.4 m•kgf, 46 ft•Ibf) 5

6
T.R
.

64 Nm (6.4 m•kgf, 46 ft•Ibf)

T.R
.

Order Job/Parts to remove Q’ty Remarks

Refer to “REAR SHOCK ABSORBER AS-
Rear brake caliper SEMBLIES AND SWINGARM” on page
4-61.

TIP
Place a suitable stand under the engine.

1 Mudguard 1
2 Rear shock absorber 2
3 Engine mounting nut/washer/bolt 1/1/1
4 Spacer 1
5 Engine bracket rod nut/washer/bolt 2/2/2
6 Engine bracket rod 2
7 Engine 1
8 Engine bracket nut/bolt 2/2
9 Engine bracket 1
For installation, reverse the removal proce-
dure.

5-4
 ENGINE REMOVAL (YP125R)

EAS37P1136

INSTALLING THE ENGINE 7 2

1. Install:
• Engine “1”
• Engine bracket “2” 7
• Engine bracket rods “3” 6
• Spacer “4”
• Engine mounting nut/washer/bolt “5”
• Engine bracket rod bolts/washers/nuts “6” 7
• Engine bracket nuts/bolts “7”
• Rear shock absorber assemblies “8” 6
TIP 8
• Do not fully tighten the bolts and nuts. 5
4
• Be sure to install each engine bracket rod “3”
with the white mark “a” on the rod facing for-
ward. 3
6
1 3
5
6

a
3. Tighten:
• Rear shock absorber assembly upper nuts
• Rear shock absorber assembly lower bolts

3 Rear shock absorber assembly

2. Tighten: upper nut
T.
R.

32 Nm (3.2 m·kgf, 23 ft·lbf)

• Engine bracket rod nuts “6”
Rear shock absorber assembly
• Engine mounting nut “5” lower bolt
• Engine bracket nuts “7” 18 Nm (1.8 m·kgf, 13 ft·lbf)
Engine bracket rod nut 4. Install:
64 Nm (6.4 m·kgf, 46 ft·lbf)
T.
R.

Engine mounting nut • Gasket New

43 Nm (4.3 m·kgf, 31 ft·lbf) • Exhaust pipe
Engine bracket nut • Exhaust pipe nuts
59 Nm (5.9 m·kgf, 43 ft·lbf) (temporarily tighten)
5. Install:
• Muffler
• Muffler mounting bolts
(temporarily tighten)
TIP
Install the muffler mounting bolts in the proper in-
stalling sequence as shown.
6. Tighten:
• Muffler mounting bolts

Muffler mounting bolt

53 Nm (5.3 m·kgf, 3.8 ft·lbf)
T.
R.

5-5
 ENGINE REMOVAL (YP125R)

TIP
Tighten the muffler mounting bolts in the proper
tightening sequence as shown.

2
3

7. Tighten:
• Exhaust pipe nuts

Exhaust pipe nut

20 Nm (2.0 m·kgf, 14 ft·lbf)
T.
R.

8. Tighten:
• Muffler joint bolt
• O2 sensor

Muffler joint bolt

14 Nm (1.4 m·kgf, 10 ft·lbf)
T.
R.

O2 sensor
45 Nm (4.5 m·kgf, 32 ft·lbf)

5-6
 CYLINDER HEAD (YP125R)

EAS37P1001

CYLINDER HEAD (YP125R)

Removing the cylinder head

10 Nm (1.0 m•kgf, 7.2 ft•Ibf) 8 Nm (0.8 m•kgf, 5.8 ft•Ibf) 10 Nm (1.0 m•kgf, 7.2 ft•Ibf)
T.R

T.R

T.R
.

.
13 Nm (1.3 m•kgf, 9.4 ft•Ibf)
T.R
.

9
18 Nm (1.8 m•kgf, 13 ft•Ibf)
T.R
.

22 Nm (2.2 m•kgf, 16 ft•Ibf) 10 New

LS
T.R
.

E
New
1
New
(4) (4) New
14
3
2

LS

14
13 New 4
(4)
6
New New
12
11 5
8 New 7 Nm (0.7 m•kgf, 5.1 ft•Ibf)
T.R
.

7 30 Nm (3.0 m•kgf, 22 ft•Ibf)

T.R
.

New

7 Nm (0.7 m•kgf, 5.1 ft•Ibf)

T.R
.

10 Nm (1.0 m•kgf, 7.2 ft•Ibf)

T.R
.

Order Job/Parts to remove Q’ty Remarks

Refer to “THERMOSTAT (YP125R)” on page
Thermostat 6-3.
Refer to “WATER PUMP (YP125R)” on page
Water pump 6-5.
Refer to “ENGINE REMOVAL (YP125R)” on
Engine page 5-1.
1 Timing mark accessing plug 1
2 Spark plug 1
3 Coolant temperature sensor 1
4 V-belt case cover 1
5 V-belt case air duct 1
6 V-belt case air filter element 1
7 Cylinder head cover 1
8 Cylinder head cover gasket 1
9 Timing chain tensioner 1
10 Timing chain tensioner gasket 1
11 Camshaft sprocket 1

5-7
 CYLINDER HEAD (YP125R)

Removing the cylinder head

10 Nm (1.0 m•kgf, 7.2 ft•Ibf) 8 Nm (0.8 m•kgf, 5.8 ft•Ibf) 10 Nm (1.0 m•kgf, 7.2 ft•Ibf)
T.R

T.R

T.R
.

.
13 Nm (1.3 m•kgf, 9.4 ft•Ibf)
T.R
.

9
18 Nm (1.8 m•kgf, 13 ft•Ibf)
T.R
.

22 Nm (2.2 m•kgf, 16 ft•Ibf) 10 New

LS
T.R
.

E
New
1
New
(4) (4) New
14
3
2

LS

14
13 New 4
(4)
6
New New
12
11 5
8 New T.R
.
7 Nm (0.7 m•kgf, 5.1 ft•Ibf)
7 30 Nm (3.0 m•kgf, 22 ft•Ibf)
T.R
.

New

7 Nm (0.7 m•kgf, 5.1 ft•Ibf)

T.R
.

10 Nm (1.0 m•kgf, 7.2 ft•Ibf)

T.R
.

Order Job/Parts to remove Q’ty Remarks

12 Cylinder head 1
13 Cylinder head gasket 1
14 Dowel pin 2
For installation, reverse the removal proce-
dure.

5-8
 CYLINDER HEAD (YP125R)

EAS37P1002

REMOVING THE CYLINDER HEAD

1. Align:
• “I” mark “a” on the generator rotor
(with the stationary pointer “b” on the genera-
tor cover)
▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼ 1
a. Turn the primary sheave nut on the left side
of the crankshaft counterclockwise to turn the
crankshaft.

3. Remove:
• Timing chain tensioner
(along with the gasket)
• Camshaft sprocket bolt “1”
• Camshaft sprocket “2”
TIP
To prevent the timing chain from falling into the
crankcase, fasten it with a wire “3”.

b. When the piston is at TDC on the compres-

sion stroke, align the “I” mark “c” on the cam-
shaft sprocket with the stationary pointer “d”
on the cylinder head.
1

2
3
4. Remove:
• Cylinder head
TIP
• Loosen the bolts and nuts in the proper se-
quence as shown.
• Loosen each bolt and nut 1/2 of a turn at a
time. After all of the bolts and nuts are fully
loosened, remove them.
d
4
c 6 2

▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲ 3 1
2. Loosen: 5
• Camshaft sprocket bolt “1”
TIP
While holding the primary sheave nut with a EAS37P1003

CHECKING THE CYLINDER HEAD

wrench, remove the camshaft sprocket bolt.
1. Eliminate:
• Combustion chamber carbon deposits
(with a rounded scraper)

5-9
 CYLINDER HEAD (YP125R)

TIP c. If the limit is exceeded, resurface the cylinder

Do not use a sharp instrument to avoid damag- head as follows.
ing or scratching: d. Place 400–600 grit wet sandpaper on the sur-
• Spark plug bore threads face plate and resurface the cylinder head
• Valve seats using a figure-eight sanding pattern.
TIP
To ensure an even surface, rotate the cylinder
head several times.
▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲
EAS37P1004

CHECKING THE CAMSHAFT SPROCKET

1. Check:
• Camshaft sprocket
More than 1/4 tooth wear “a” → Replace the
camshaft sprocket, timing chain and crank-
2. Check: shaft as a set.
• Cylinder head
Damage/scratches → Replace.
• Cylinder head water jacket
Mineral deposits/rust → Eliminate.
3. Measure:
• Cylinder head warpage
Out of specification → Resurface the cylinder
head.

Warpage limit
0.05 mm (0.0020 in)
a. 1/4 tooth
▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼
b. Correct
a. Place a straightedge “1” and a thickness 1. Timing chain roller
gauge “2” across the cylinder head. 2. Camshaft sprocket
EAS37P1005

CHECKING THE TIMING CHAIN TENSIONER

1. Check:
• Timing chain tensioner
Cracks/damage → Replace.
▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼
a. Remove the timing chain tensioner plug.
b. While lightly pressing the timing chain ten-
sioner rod by hand, turn the tensioner rod ful-
ly clockwise with a thin screwdriver “1”.

1 2

b. Measure the warpage. c. Remove the screwdriver and slowly release

the timing chain tensioner rod.

5-10
 CYLINDER HEAD (YP125R)

b. Align the “I” mark “a” on the generator rotor

with the stationary pointer “b” on the genera-
tor cover.
c. Install the timing chain “1” onto the camshaft
sprocket “2”, then the camshaft sprocket onto
the camshaft, and then finger tighten the
camshaft sprocket bolt.
TIP
Fit the projections “c” on the camshaft into the
holes “d” in the camshaft sprocket and fit the pin
d. Make sure that the timing chain tensioner rod “e” on the decompression cam into the slot “f” in
comes out of the timing chain tensioner hous- the decompression lever on the camshaft
ing smoothly. If there is rough movement, re- sprocket.
place the timing chain tensioner.
ECA37P1001
e. Install the timing chain tensioner plug.
NOTICE
▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲
Do not turn the crankshaft when installing
EAS37P1006

INSTALLING THE CYLINDER HEAD the camshaft to avoid damage or improper

1. Tighten: valve timing.
• Cylinder head nuts “1”
a
Cylinder head nut
22 Nm (2.2 m·kgf, 16 ft·lbf)
T.
R.

• Cylinder head bolts “2” b

Cylinder head bolt
10 Nm (1.0 m·kgf, 7.2 ft·lbf)
T.
R.

TIP
• Lubricate the cylinder head nuts with engine c d
oil. 2
• Tighten the cylinder head nuts and bolts in the
proper tightening sequence as shown and
torque them in two stages.

1
3
1 5 e f
1
2 d. Make sure the “I” mark “g” on the camshaft
sprocket with the stationary pointer “h” on the
4 6 cylinder head.
2
TIP
1 When installing the camshaft sprocket, be sure
2. Install: to keep the timing chain as tight as possible on
• Camshaft sprocket the exhaust side.
• Timing chain
• Camshaft sprocket bolt
▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼
a. Turn the primary sheave nut on the left side
of the crankshaft counterclockwise to turn the
crankshaft.

5-11
 CYLINDER HEAD (YP125R)

Timing chain tensioner bolt

10 Nm (1.0 m·kgf, 7.2 ft·lbf)

T.
R.
h d. Turn the timing chain tensioner rod counter-
clockwise with a thin screwdriver “1”, make
g sure it releases, and then install the timing
chain tensioner plug.
1
2
e. While holding the primary sheave nut with a
wrench, temporarily tighten the camshaft
sprocket bolt.
f. Remove the wire from the timing chain.
▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲
3. Install:
• Timing chain tensioner gasket New
• Timing chain tensioner ▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲
▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼ 4. Turn:
a. Remove the timing chain tensioner plug.
• Crankshaft
b. While lightly pressing the timing chain ten-
(turn the primary sheave nut on the left side
sioner rod by hand, turn the tensioner rod ful-
of the crankshaft several turns counterclock-
ly clockwise with a thin screwdriver “1”.
wise)
TIP 5. Check:
Make sure that the tensioner rod has been fully • “I” mark “a”
turned clockwise. Make sure the “I” mark “a” on the generator
rotor is aligned with the stationary pointer “b”
on the generator cover.
• “I” mark “c”
Make sure the “I” mark “c” on the camshaft
1 sprocket is aligned with the stationary pointer
“d” on the cylinder head.
Out of alignment → Correct.
Refer to the installation steps above.

a
c. Install the gasket and the timing chain ten-
sioner “2” onto the cylinder.
EWA37P1001

WARNING
b
Always use a new gasket.
TIP
Apply sealant to the threads of the timing chain
tensioner bolts.

Yamaha bond No. 1215

90890-85505
(Three Bond No.1215®)

5-12
 CYLINDER HEAD (YP125R)

6. Tighten:
• Camshaft sprocket bolt

Camshaft sprocket bolt

30 Nm (3.0 m·kgf, 22 ft·lbf)
T.
R.

ECA37P1002

NOTICE
Be sure to tighten the camshaft sprocket bolt
to the specified torque to avoid the possibil-
ity of the bolt coming loose and damaging
the engine.
7. Measure:
• Valve clearance
Out of specification → Adjust.
Refer to “ADJUSTING THE VALVE CLEAR-
ANCE” on page 3-6.

5-13
 CAMSHAFT (YP125R)

EAS37P1007

CAMSHAFT (YP125R)
Removing the rocker arms and camshaft

7 Nm (0.7 m•kgf, 5.1 ft•Ibf)

T.R
.

1 2 M
12
6

7
M
LT
E

8
3
2
1 E

2 5 4
M
1 6
LT

7 Nm (0.7 m•kgf, 5.1 ft•Ibf) M 7 Nm (0.7 m•kgf, 5.1 ft•Ibf)

T.R
.

T.R
.

Order Job/Parts to remove Q’ty Remarks

Refer to “CYLINDER HEAD (YP125R)” on
Cylinder head page 5-7.
1 Locknut 4
2 Adjusting screw 4
3 Decompression cam 1
4 Camshaft retainer 1
5 Camshaft 1
6 Rocker arm shaft 2
7 Intake rocker arm 1
8 Exhaust rocker arm 1
For installation, reverse the removal proce-
dure.

5-14
 CAMSHAFT (YP125R)

EAS37P1008

REMOVING THE CAMSHAFT

1. Remove:
• Camshaft “1”
TIP
Screw an M8 bolt “2” into the threaded end of the
camshaft, and then pull out the camshaft.

EAS37P1009

CHECKING THE CAMSHAFT

1. Check:
• Camshaft lobes 3. Check:
Blue discoloration/pitting/scratches → Re- • Camshaft oil passage
place the camshaft. Obstruction → Blow out with compressed air.
2. Measure:
EAS37P1010
• Camshaft lobe dimensions “a” and “b” CHECKING THE DECOMPRESSION SYSTEM
Out of specification → Replace the camshaft. 1. Check:
• Decompression system
Camshaft lobe dimensions
▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼
Intake A a. Check the decompression system with the
30.225–30.325 mm (1.1900–
camshaft sprocket and the decompression
1.1939 in)
Limit cam installed to the camshaft.
30.125 mm (1.1860 in) b. Check that the decompression lever “1”
Intake B moves smoothly.
25.064–25.164 mm (0.9868– c. Without operating the decompression lever,
0.9907 in) check that the decompression cam “2”
Limit projects from the camshaft (exhaust cam) as
24.964 mm (0.9828 in) shown in the illustration “A”.
Exhaust A d. Move the decompression lever in the direc-
30.261–30.361 mm (1.1914– tion of the arrow shown and check that the
1.1953 in) decompression cam does not project from
Limit the camshaft (exhaust cam) as shown in the
30.161 mm (1.1874 in)
illustration “B”.
Exhaust B
25.121–25.221 mm (0.9890–
0.9930 in) 1
Limit
25.021 mm (0.9851 in)

5-15
 CAMSHAFT (YP125R)

A Rocker arm inside diameter

2 9.985–10.000 mm (0.3931–
0.3937 in)
Limit
10.015 mm (0.3943 in)

B 2

4. Measure:
• Rocker arm shaft outside diameter “a”
Out of specification → Replace.

Rocker arm shaft outside diame-

▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲
ter
EAS37P1011
9.966–9.976 mm (0.3924–0.3928
CHECKING THE ROCKER ARMS AND in)
ROCKER ARM SHAFTS Limit
The following procedure applies to all of the 9.940 mm (0.3913 in)
rocker arms and rocker arm shafts.
1. Check:
• Rocker arm
• Rocker arm roller “1”
Damage/wear → Replace.

5. Calculate:
• Rocker-arm-to-rocker-arm-shaft clearance
TIP
Calculate the clearance by subtracting the rock-
2. Check: er arm shaft outside diameter from the rocker
• Rocker arm shaft arm inside diameter.
Blue discoloration/excessive wear/pit-
ting/scratches → Replace or check the lubri- Out of specification → Replace the defective
cation system. part(s).
3. Measure:
Rocker-arm-to-rocker-arm-shaft
• Rocker arm inside diameter “a”
clearance
Out of specification → Replace. 0.009–0.034 mm (0.0004–0.0013
in)
Limit
0.075 mm (0.0030 in)

5-16
 CAMSHAFT (YP125R)

EAS37P1012

INSTALLING THE CAMSHAFT AND ROCKER b

ARMS
1. Lubricate:
• Camshaft
1
Recommended lubricant
Camshaft a
Molybdenum disulfide grease
Camshaft bearing
Engine oil
5. Install:
2. Lubricate: • Camshaft retainer
• Rocker arms
• Rocker arm shafts Camshaft retainer bolt
7 Nm (0.7 m·kgf, 5.1 ft·lbf)

T.
R.
Recommended lubricant LOCTITE®
Molybdenum disulfide oil

3. Install:
• Rocker arms
• Rocker arm shafts “1”
TIP
• Make sure that the cutout “a” in each rocker
arm shaft is facing downward as shown in the
illustration.
• Make sure the rocker arm shafts (intake and
exhaust) are completely pushed into the cylin-
der head.

1 a

4. Install:
• Camshaft “1”
TIP
Make sure that the camshaft projections “a” and
hole “b” are positioned as shown in the illustra-
tion.

5-17
 VALVES AND VALVE SPRINGS (YP125R)

EAS37P1013

VALVES AND VALVE SPRINGS (YP125R)

Removing the valves and valve springs

1
2 5
1 3 M M

6 New
7
New 8
5
2
3
M
M
8 New
New 6
7
8 New
New 6 7 M

M 4
3

2 7
8 New
6 New

3 4
M M
1 2
1

Order Job/Parts to remove Q’ty Remarks

Refer to “CYLINDER HEAD (YP125R)” on
Cylinder head page 5-7.
Refer to “CAMSHAFT (YP125R)” on page
Rocker arms/Camshaft 5-14.
1 Valve cotter 8
2 Upper spring seat 4
3 Valve spring 4
4 Intake valve 2
5 Exhaust valve 2
6 Valve stem seal 4
7 Lower spring seat 4
8 Valve guide 4
For installation, reverse the removal proce-
dure.

5-18
 VALVES AND VALVE SPRINGS (YP125R)

EAS37P1014

REMOVING THE VALVES

The following procedure applies to all of the
valves and related components. 2
TIP
Before removing the internal parts of the cylinder
head (e.g., valves, valve springs, valve seats),
make sure the valves properly seal.
1. Check: 1
• Valve sealing
Leakage at the valve seat → Check the valve 3. Remove:
face, valve seat, and valve seat width. • Upper spring seat “1”
Refer to “CHECKING THE VALVE SEATS” • Valve spring “2”
on page 5-21. • Valve “3”
▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼
• Valve stem seal “4”
a. Pour a clean solvent “a” into the intake and • Lower spring seat “5”
exhaust ports. TIP
b. Check that the valves properly seal. Identify the position of each part very carefully so
TIP that it can be reinstalled in its original place.
There should be no leakage at the valve seat “1”.

EAS37P1015

▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲ CHECKING THE VALVES AND VALVE

2. Remove: GUIDES
• Valve cotters “1” The following procedure applies to all of the
valves and valve guides.
TIP
1. Measure:
Remove the valve cotters by compressing the • Valve-stem-to-valve-guide clearance
valve spring with the valve spring compressor Out of specification → Replace the valve
and the valve spring compressor attachment “2”. guide.
• Valve-stem-to-valve-guide clearance =
Valve spring compressor Valve guide inside diameter “a” -
90890-04019 Valve stem diameter “b”
YM-04019
Valve spring compressor attach-
ment
90890-04108
Valve spring compressor adapt-
er 22 mm
YM-04108

5-19
 VALVES AND VALVE SPRINGS (YP125R)

b. Install the new valve guide with the valve

Valve-stem-to-valve-guide clear- guide installer “2” and valve guide remover
ance (intake) “1”.
0.010–0.037 mm (0.0004–0.0015
in) Valve guide position
Limit Intake
0.080 mm (0.0031 in) 17.0–17.4 mm (0.670–0.685 in)
Valve-stem-to-valve-guide clear- Exhaust
ance (exhaust) 14.0–14.4 mm (0.551–0.567 in)
0.025–0.052 mm (0.0010–0.0020
in)
Limit
0.100 mm (0.0039 in)

a. Valve guide position

c. After installing the valve guide, bore the valve
guide with the valve guide reamer “3” to ob-
tain the proper valve-stem-to-valve-guide
clearance.

2. Replace:
• Valve guide TIP
TIP
After replacing the valve guide, reface the valve
To ease valve guide removal and installation, seat.
and to maintain the correct fit, heat the cylinder
head to 100 °C (212 °F) in an oven.
Valve guide remover (ø4.5)
▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼ 90890-04116
a. Remove the valve guide with the valve guide Valve guide remover (4.5 mm)
remover “1”. YM-04116
Valve guide installer (ø4.5)
90890-04117
Valve guide installer (4.5 mm)
YM-04117
Valve guide reamer (ø4.5)
90890-04118
Valve guide reamer (4.5 mm)
YM-04118

▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲

5-20
 VALVES AND VALVE SPRINGS (YP125R)

3. Eliminate: EAS37P1016

CHECKING THE VALVE SEATS

• Carbon deposits
The following procedure applies to all of the
(from the valve face and valve seat)
valves and valve seats.
4. Check:
1. Eliminate:
• Valve face
• Carbon deposits
Pitting/wear → Grind the valve face.
(from the valve face and valve seat)
• Valve stem end
2. Check:
Mushroom shape or diameter larger than the
• Valve seat
body of the valve stem → Replace the valve.
Pitting/wear → Replace the cylinder head.
5. Measure:
3. Measure:
• Valve margin thickness “a”
• Valve seat width “a”
Out of specification → Replace the valve.
Out of specification → Replace the cylinder
Valve margin thickness D (intake) head.
0.85–1.15 mm (0.0335–0.0453 in)
Valve margin thickness D (ex- Valve seat width C (intake)
haust) 0.90–1.10 mm (0.0354–0.0433 in)
0.85–1.15 mm (0.0335–0.0453 in) Limit
1.6 mm (0.06 in)
Valve seat width C (exhaust)
0.90–1.10 mm (0.0354–0.0433 in)
Limit
1.6 mm (0.06 in)

6. Measure:
• Valve stem runout
Out of specification → Replace the valve.
TIP
• When installing a new valve, always replace ▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼
the valve guide. a. Apply Mechanic’s blueing dye (Dykem) “b”
• If the valve is removed or replaced, always re- onto the valve face.
place the valve stem seal.

Valve stem runout

0.010 mm (0.0004 in)

b. Install the valve into the cylinder head.

c. Press the valve through the valve guide and
onto the valve seat to make a clear impres-
sion.
d. Measure the valve seat width.

5-21
 VALVES AND VALVE SPRINGS (YP125R)

TIP e. Apply a fine lapping compound to the valve

Where the valve seat and valve face contacted face and repeat the above steps.
one another, the blueing will have been re- f. After every lapping procedure, be sure to
moved. clean off all of the lapping compound from the
valve face and valve seat.
▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲ g. Apply Mechanic’s blueing dye (Dykem) “b”
4. Lap: onto the valve face.
• Valve face
• Valve seat
TIP
After replacing the cylinder head or replacing the
valve and valve guide, the valve seat and valve
face should be lapped.
▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼
a. Apply a coarse lapping compound “a” to the
valve face.
ECA13790

NOTICE h. Install the valve into the cylinder head.

i. Press the valve through the valve guide and
Do not let the lapping compound enter the
onto the valve seat to make a clear impres-
gap between the valve stem and the valve
sion.
guide.
j. Measure the valve seat width again. If the
valve seat width is out of specification, reface
and lap the valve seat.
▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲
EAS37P1017

CHECKING THE VALVE SPRINGS

The following procedure applies to all of the
valve springs.
1. Measure:
• Valve spring free length “a”
Out of specification → Replace the valve
b. Apply molybdenum disulfide oil onto the spring.
valve stem.
c. Install the valve into the cylinder head. Free length (intake)
d. Turn the valve until the valve face and valve 41.71 mm (1.64 in)
seat are evenly polished, and then clean off Limit
all of the lapping compound. 39.62 mm (1.56 in)
Free length (exhaust)
TIP
41.71 mm (1.64 in)
For the best lapping results, lightly tap the valve Limit
seat while rotating the valve back and forth be- 39.62 mm (1.56 in)
tween your hands.

5-22
 VALVES AND VALVE SPRINGS (YP125R)

2. Measure: 1. Deburr:
• Compressed valve spring force “a” • Valve stem end
Out of specification → Replace the valve (with an oil stone)
spring.

Installed compression spring

force (intake)
140–162 N (14.28–16.52 kgf,
31.47–36.42 lbf)
Installed compression spring
force (exhaust)
140–162 N (14.28–16.52 kgf,
31.47–36.42 lbf)
Installed length (intake)
35.30 mm (1.39 in) 2. Lubricate:
Installed length (exhaust) • Valve stem “1”
35.30 mm (1.39 in) • Valve stem seal “2”
(with the recommended lubricant)

Recommended lubricant
Molybdenum disulfide oil

b. Installed length
3. Measure:
• Valve spring tilt “a”
Out of specification → Replace the valve 3. Install:
spring. • Lower spring seat “1”
Spring tilt (intake) • Valve stem seal “2” New
2.5°/1.8 mm • Valve “3”
Spring tilt (exhaust) • Valve spring “4”
2.5°/1.8 mm • Upper spring seat “5”
(into the cylinder head)
TIP
• Make sure each valve is installed in its original
place.
• Install the valve springs with the larger pitch “a”
facing up.

EAS37P1018

INSTALLING THE VALVES

The following procedure applies to all of the
valves and related components.

5-23
 VALVES AND VALVE SPRINGS (YP125R)

b. Smaller pitch
4. Install:
• Valve cotters “1”
TIP
Install the valve cotters by compressing the
valve spring with the valve spring compressor
and the valve spring compressor attachment “2”.

Valve spring compressor

90890-04019
YM-04019
Valve spring compressor attach-
ment
90890-04108
Valve spring compressor adapt-
er 22 mm
YM-04108

5. To secure the valve cotters onto the valve

stem, lightly tap the valve tip with a soft-face
hammer.
ECA13800

NOTICE
Hitting the valve tip with excessive force
could damage the valve.

5-24
 CYLINDER AND PISTON (YP125R)

EAS37P1019

CYLINDER AND PISTON (YP125R)

Removing the cylinder and piston

3 New
4
2

New
7 Nm (0.7 m•kgf, 5.1 ft•Ibf) 5 New 7
T.R
.

10
9
8 6
5 New

Order Job/Parts to remove Q’ty Remarks

Refer to “CYLINDER HEAD (YP125R)” on
Cylinder head page 5-7.
1 Timing chain guide (exhaust side) 1
2 Cylinder 1
3 Cylinder gasket 1
4 Dowel pin 2
5 Clip 2
6 Piston pin 1
7 Piston 1
8 Top ring 1
9 2nd ring 1
10 Oil ring 1
For installation, reverse the removal proce-
dure.

5-25
 CYLINDER AND PISTON (YP125R)

EAS37P1020

REMOVING THE PISTON TIP

1. Remove: When removing a piston ring, open the end gap
• Piston pin clips “1” with your fingers and lift the other side of the ring
• Piston pin “2” over the piston crown.
• Piston “3”
ECA13810

NOTICE
Do not use a hammer to drive the piston pin
out.
TIP
• Before removing the piston pin clips, cover the
crankcase opening with a clean rag to prevent
them from falling into the crankcase.
• Before removing the piston pin, deburr the pis-
ton pin clip groove and the piston pin bore ar- EAS37P1021

ea. If both areas are deburred and the piston CHECKING THE CYLINDER AND PISTON
pin is still difficult to remove, remove it with the 1. Check:
piston pin puller set “4”. • Piston wall
• Cylinder wall
Vertical scratches → Rebore or replace the
Piston pin puller set cylinder, and replace the piston and piston
90890-01304 rings as a set.
Piston pin puller
2. Measure:
YU-01304
• Piston-to-cylinder clearance
▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼
a. Measure cylinder bore “C” with the cylinder
bore gauge.
TIP
1 Measure cylinder bore “C” by taking side-to-side
and front-to-back measurements of the cylinder.
Then, find the average of the measurements.

Bore
3 2 52.000–52.010 mm (2.0472–
2.0476 in)
Taper limit
0.050 mm (0.0020 in)
Out of round limit
0.005 mm (0.0002 in)

“C” = maximum of D1–D2

“T” = maximum of D1 or D2 - maximum of D5
or D6
“R” = maximum of D1, D3 or D5 - minimum of
2. Remove:
D2, D4 or D6
• Top ring
• 2nd ring
• Oil ring

5-26
 CYLINDER AND PISTON (YP125R)

EAS37P1081

CHECKING THE PISTON RINGS

1. Measure:
• Piston ring side clearance
Out of specification → Replace the piston
and piston rings as a set.
TIP
Before measuring the piston ring side clearance,
eliminate any carbon deposits from the piston
ring grooves and piston rings.
b. If out of specification, rebore or replace the
cylinder, and replace the piston and piston Piston ring
rings as a set. Top ring
c. Measure piston skirt diameter D “a” with the Ring side clearance
micrometer. 0.040–0.080 mm (0.0016–
0.0031 in)
Limit
0.120 mm (0.0047 in)
2nd ring
Ring side clearance
0.030–0.070 mm (0.0012–
0.0028 in)
Limit
0.120 mm (0.0047 in)

b. 5 mm (0.20 in) from the bottom edge of the

piston

Piston
Diameter D
51.962–51.985 mm (2.0457–
2.0466 in)

d. If out of specification, replace the piston and

piston rings as a set. 2. Install:
e. Calculate the piston-to-cylinder clearance • Piston ring
with the following formula. (into the cylinder)
• Piston-to-cylinder clearance = TIP
Cylinder bore “C” - Level the piston ring into the cylinder with the
Piston skirt diameter “D”
piston crown.

Piston-to-cylinder clearance
0.015–0.048 mm (0.0006–0.0019
in)
Limit
0.15 mm (0.0059 in)

f. If out of specification, rebore or replace the

cylinder, and replace the piston and piston
rings as a set.
▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲
a. 10 mm (0.39 in)

5-27
 CYLINDER AND PISTON (YP125R)

3. Measure: 3. Measure:
• Piston ring end gap • Piston pin bore diameter “b”
Out of specification → Replace the piston Out of specification → Replace the piston.
ring.
TIP
Piston pin bore inside diameter
14.002–14.013 mm (0.5513–
The oil ring expander spacer end gap cannot be 0.5517 in)
measured. If the oil ring rail gap is excessive, re- Limit
place all three piston rings. 14.043 mm (0.5529 in)

Piston ring
Top ring
End gap (installed)
0.10–0.25 mm (0.0039–0.0098
in)
Limit
0.50 mm (0.0197 in)
2nd ring
End gap (installed)
0.10–0.25 mm (0.0039–0.0098
in)
Limit 4. Calculate:
0.60 mm (0.0236 in) • Piston-pin-to-piston-pin-bore clearance
Oil ring Out of specification → Replace the piston pin
End gap (installed) and piston as a set.
0.20–0.70 mm (0.0079–0.0276 • Piston-pin-to-piston-pin-bore clearance =
in) Piston pin bore diameter “b” -
Piston pin outside diameter “a”
EAS37P1022

CHECKING THE PISTON PIN

1. Check: Piston-pin-to-piston-pin-bore
• Piston pin clearance
Blue discoloration/grooves → Replace the 0.002–0.018 mm (0.0001–0.0007
in)
piston pin, and then check the lubrication sys-
tem.
EAS37P1023
2. Measure: CHECKING THE TIMING CHAIN GUIDE
• Piston pin outside diameter “a” 1. Check:
Out of specification → Replace the piston pin. • Timing chain guide (exhaust side)
Damage/wear → Replace.
Piston pin outside diameter
13.995–14.000 mm (0.5510– EAS37P1024

0.5512 in) INSTALLING THE PISTON AND CYLINDER

Limit 1. Install:
13.975 mm (0.5502 in) • Top ring “1”
• 2nd ring “2”
• Upper oil ring rail “3”
• Oil ring expander “4”
• Lower oil ring rail “5”
TIP
Be sure to install the piston rings so that the
manufacturer marks or numbers face up.

5-28
 CYLINDER AND PISTON (YP125R)

e 120˚ a

120˚ 120˚

f f
d c b
A

2. Install: a. Top ring

• Piston “1” b. Upper oil ring rail
• Piston pin “2” c. Oil ring expander
• Piston pin clips “3” New d. Lower oil ring rail
TIP e. 2nd ring
f. 20 mm (0.79 in)
• Apply engine oil to the piston pin.
A. Intake side
• Make sure the punch mark “a” on the piston
points towards the exhaust side of the cylinder. 5. Install:
• Before installing the piston pin clips, cover the • Dowel pins
crankcase opening with a clean rag to prevent • Cylinder gasket New
the clips from falling into the crankcase. • Cylinder “1”
TIP

1 • While compressing the piston rings with one

hand, install the cylinder with the other hand.
• Pass the timing chain and timing chain guide
(intake side) through the timing chain cavity.
a

2
1
3 New

3. Lubricate:
• Piston
• Piston rings
• Cylinder
(with the recommended lubricant)

Recommended lubricant
Engine oil

4. Offset:
• Piston ring end gaps

5-29
 V-BELT AUTOMATIC TRANSMISSION (YP125R)

EAS37P1137

V-BELT AUTOMATIC TRANSMISSION (YP125R)

Removing the V-belt case cover

10 Nm (1.0 m•kgf, 7.2 ft•Ibf)

T.R
.
9

New 7 (8)

8
New 6 4
5
New (3)

3
1

7 Nm (0.7 m•kgf, 5.1 ft•Ibf)

T.R
.

7 Nm (0.7 m•kgf, 5.1 ft•Ibf)

T.R
.

Order Job/Parts to remove Q’ty Remarks

Refer to “GENERAL CHASSIS” on page
Bottom cover/Air filter case 4-1.
1 V-belt case cover 1
2 V-belt case air duct joint 1
3 V-belt case air duct 1
4 V-belt case air filter element 1
5 V-belt case 1
6 V-belt case gasket 1 1
7 V-belt case gasket 2 1
8 Dowel pin 1
9 Bearing 1
For installation, reverse the removal proce-
dure.

5-30
 V-BELT AUTOMATIC TRANSMISSION (YP125R)

Removing the V-belt, primary sheave and secondary sheave

8
7

6
New

5
4

* 11 *
3
10 New
14 2 1
12 10 New
13
* 55 Nm (5.5 m•kgf, 40 ft•Ibf)
T.R
.

9 * 60 Nm (6.0 m•kgf, 43 ft•Ibf)

T.R
.

Order Job/Parts to remove Q’ty Remarks

1 Primary sheave nut/Washer 1/1
2 Primary fixed sheave 1
3 Washer 1
4 Secondary sheave nut 1
5 Spacer 1
6 Clutch housing 1
7 Secondary sheave assembly 1
8 V-belt 1
9 Primary sliding sheave 1
10 Oil seal 2
11 Spacer 1
12 Cam 1
13 Primary sheave weight 6
14 Slider 3
For installation, reverse the removal proce-
dure.

* Apply BEL-RAY assembly lube®.

5-31
 V-BELT AUTOMATIC TRANSMISSION (YP125R)

Disassembling the secondary sheave

7 3 New
6
4

5 New
2

1
12 New 13
8

11 New 9

90 Nm (9.0 m•kgf, 65 ft•Ibf)

T.R
.
11 New
* 10 New

8 8

Order Job/Parts to remove Q’ty Remarks

1 Clutch carrier nut 1
2 Clutch carrier 1
3 Clip 3
4 Clutch carrier plate 1
5 Clutch shoe spring 3
6 Compression spring 1
7 Spring seat 1
8 Guide pin 3
9 Secondary sliding sheave 1
10 O-ring 2
11 Oil seal 2
12 Oil seal 1
13 Secondary fixed sheave 1
For assembly, reverse the disassembly pro-
cedure.

* Apply BEL-RAY assembly lube®.

5-32
 V-BELT AUTOMATIC TRANSMISSION (YP125R)

EAS37P1025

REMOVING THE PRIMARY SHEAVE

1. Remove:
• V-belt case
TIP
Loosen each bolt 1/4 of a turn at a time, in stag-
es and in a crisscross pattern. After all of the
bolts are fully loosened, remove them.
2. Remove:
• Primary sheave nut “1”
• Washer 2. Loosen:
• Primary fixed sheave “2” • Clutch carrier nut “1”
ECA13860

TIP NOTICE
While holding the primary fixed sheave with the Do not remove the clutch carrier nut at this
rotor holding tool “3”, loosen the primary sheave stage.
nut.
TIP
Rotor holding tool While holding the clutch carrier with the sheave
90890-01235 holder “2”, loosen the clutch carrier nut one full
Universal magneto & rotor holder turn with the locknut wrench “3”.
YU-01235
Sheave holder
90890-01701
Primary clutch holder
YS-01880-A
Locknut wrench
90890-01348
YM-01348

2
EAS37P1026

REMOVING THE SECONDARY SHEAVE

1. Remove:
• Secondary sheave nut “1” 3
• Spacer 1
• Clutch housing “2”
TIP
3. Remove:
While holding the clutch housing with the sheave
• Secondary sheave assembly “1”
holder “3”, loosen the secondary sheave nut.
• V-belt “2”
TIP
Sheave holder
90890-01701 Remove the V-belt and secondary sheave as-
Primary clutch holder sembly from the primary sheave side.
YS-01880-A

5-33
 V-BELT AUTOMATIC TRANSMISSION (YP125R)

EAS37P1027 EAS37P1029

DISASSEMBLING THE SECONDARY CHECKING THE CLUTCH SHOES

SHEAVE The following procedure applies to all of the
1. Remove: clutch shoes.
• Clutch carrier nut “1” 1. Check:
TIP • Clutch shoe
While compressing the compression spring with Damage/wear → Replace the clutch shoes
the clutch spring holder “2” and clutch spring and springs as a set.
holder arm “3”, remove the clutch carrier nut. Glazed areas → Sand with coarse sandpa-
per.
TIP
Clutch spring holder
90890-01337 After sanding the glazed areas, clean the clutch
Clutch spring holder arm with a cloth.
90890-01464
2. Measure:
• Clutch shoe thickness “a”
Out of specification → Replace the clutch
shoes and springs as a set.

Clutch shoe thickness

2.0 mm (0.08 in)
Wear limit
1.0 mm (0.04 in)

EAS37P1028

CHECKING THE CLUTCH HOUSING

1. Check:
• Clutch housing
Damage/wear → Replace.
2. Measure:
• Clutch housing inside diameter “a”
Out of specification → Replace the clutch
housing. EAS37P1030

CHECKING THE V-BELT

Clutch housing inside diameter 1. Check:
135.0 mm (5.31 in) • V-belt “1”
Limit Cracks/damage/wear → Replace.
135.5 mm (5.33 in)
Grease/oil → Clean the primary and second-
ary sheave.
2. Measure:
• V-belt width “2”
Out of specification → Replace.

5-34
 V-BELT AUTOMATIC TRANSMISSION (YP125R)

EAS37P1033

V-belt width CHECKING THE PRIMARY SHEAVE

22.0 mm (0.87 in) SLIDERS
Limit 1. Check:
19.8 mm (0.78 in) • Primary sheave slider
Cracks/damage/wear → Replace.
EAS37P1034

CHECKING THE SECONDARY SHEAVE

1. Check:
• Secondary fixed sheave
• Secondary sliding sheave
Cracks/damage/wear → Replace the sec-
ondary fixed and sliding sheaves as a set.
2. Check:
• Torque cam groove “1”
Damage/wear → Replace the secondary
EAS37P1031
fixed and sliding sheaves as a set.
CHECKING THE PRIMARY SHEAVE
3. Check:
1. Check:
• Guide pin “2”
• Primary sliding sheave
Damage/wear → Replace the secondary
• Primary fixed sheave
fixed and sliding sheaves as a set.
• Spacer
Cracks/damage/wear → Replace the primary
sliding sheave and primary fixed sheave as a
set.
EAS37P1032

CHECKING THE PRIMARY SHEAVE

WEIGHTS
The following procedure applies to all of the pri-
mary sheave weights.
1. Check:
• Primary sheave weight 4. Check:
Cracks/damage/wear → Replace. • Spring free length
2. Measure: Out of specification → Replace the spring.
• Primary sheave weight outside diameter
Out of specification → Replace. Compression spring free length
112.0 mm (4.41 in)
Weight outside diameter Limit
20.0 mm (0.79 in) 106.4 mm (4.19 in)
Limit
19.5 mm (0.77 in)

EAS37P1035

ASSEMBLING THE PRIMARY SHEAVE

1. Clean:
• Primary fixed sheave

5-35
 V-BELT AUTOMATIC TRANSMISSION (YP125R)

• Primary sliding sheave 2. Install:

• Spacer • Oil seal New
• Primary sheave weights • Secondary sliding sheave “1”
• Cam
TIP
2. Lubricate:
• Oil seal Install the secondary sliding sheave onto the
• Primary sliding sheave secondary fixed sheave “2” with the oil seal
• Spacer guide “3”.

Recommended lubricant Oil seal guide (ø41)

BEL-RAY assembly lube® 90890-01396

TIP
Fill the notches of the primary sliding sheave
3
with grease. Apply grease to the inner surface of
the primary sliding sheave as shown.
ECA37P1003

NOTICE 1
2
Do not get any grease on the surfaces of the
sheaves. If any grease gets on the sheaves,
be sure to wipe it off with alcohol, etc.
3. Install:
• Guide pins “1”
4. Lubricate:
• Guide pin grooves “2”
• O-rings “3” New
(with the recommended lubricant)

Recommended lubricant
BEL-RAY assembly lube®

EAS37P1036

ASSEMBLING THE SECONDARY SHEAVE

1. Lubricate:
• Secondary fixed sheave inner surface “1”
• Secondary sliding sheave inner surface “2”
• Oil seals
• Bearing
(with the recommended lubricant)

Recommended lubricant
BEL-RAY assembly lube® 5. Install:
• Spring seat
• Compression spring
• Clutch carrier “1”
• Clutch carrier nut “2”
TIP
• While compressing the compression spring
with the clutch spring holder “3” and clutch
spring holder arm “4”, install the clutch carrier
nut.

5-36
 V-BELT AUTOMATIC TRANSMISSION (YP125R)

• Install the clutch carrier nut “2” with its tapered 2. Tighten:
side “a” facing the clutch carrier. • Clutch carrier nut “1”

Clutch carrier nut

Clutch spring holder
90 Nm (9.0 m·kgf, 65 ft·lbf)

T.
90890-01337

R.
Clutch spring holder arm
90890-01464 TIP
While holding the clutch carrier with the sheave
holder “2”, tighten the clutch carrier nut with the
locknut wrench “3”.

Sheave holder
90890-01701
Primary clutch holder
YS-01880-A
Locknut wrench
90890-01348
YM-01348

3
1
a
EAS37P1037
3. Install:
INSTALLING THE V-BELT
• Clutch housing “1”
1. Install:
• Spacer
• V-belt “1”
• Secondary sheave nut “2”
• Secondary sheave assembly “2”
ECA37P1004

NOTICE Secondary sheave nut

60 Nm (6.0 m·kgf, 43 ft·lbf)
T.

Do not allow grease to come in contact with

R.

the V-belt or secondary sheave assembly. TIP

TIP While holding the clutch housing with the sheave
• Install the V-belt with the printed arrow mark on holder “3”, tighten the secondary sheave nut.
the V-belt facing in the direction shown in the il-
lustration. Sheave holder
• Install the V-belt onto the primary sheave side. 90890-01701
Primary clutch holder
YS-01880-A

5-37
 V-BELT AUTOMATIC TRANSMISSION (YP125R)

4. Install: 6. Install:
• V-belt “1” • V-belt case
• Primary fixed sheave “2” TIP
• Washer • Make sure that the V-belt case gasket lip fits
• Primary sheave nut “3” properly around the V-belt case.
TIP • Tighten the V-belt case bolts in stages and in a
Install the V-belt in the primary sheave (when the crisscross pattern.
pulley is at its widest position) and in the second-
ary sheave (when the pulley is at its narrowest
position), and make sure the V-belt is tight.
ECA37P1014

NOTICE
Do not allow grease to contact the primary
sheave assembly.

2 3 1

5. Tighten:
• Primary sheave nut “1”

Primary sheave nut

55 Nm (5.5 m·kgf, 40 ft·lbf)
T.
R.

TIP
While holding the primary fixed sheave with the
rotor holding tool “2”, tighten the primary sheave
nut.

Rotor holding tool

90890-01235
Universal magneto & rotor holder
YU-01235

5-38
 STARTER CLUTCH AND GENERATOR (YP125R)

EAS37P1038

STARTER CLUTCH AND GENERATOR (YP125R)

Removing the generator cover and stator coil
1

10 Nm (1.0 m•kgf, 7.2 ft•Ibf)

T.R
.
4
LT
LT

5
7 New

LS
(3)

LS
4

New 3 2
10 Nm (1.0 m•kgf, 7.2 ft•Ibf) LS
T.R
.

LT 6

(9)
10 Nm (1.0 m•kgf, 7.2 ft•Ibf) New
T.R
.

8 Nm (0.8 m•kgf, 5.8 ft•Ibf)

T.R
.

Order Job/Parts to remove Q’ty Remarks

Drain.
Engine oil Refer to “CHANGING THE ENGINE OIL” on
page 3-12.
Refer to “ENGINE REMOVAL (YP125R)” on
Muffler/Exhaust pipe page 5-1.
Crankshaft position sensor coupler/Stator as-
1 1/1 Disconnect.
sembly coupler
2 Generator cover 1
3 Generator cover gasket 1
4 Dowel pin 2
5 Crankshaft position sensor 1
6 Stator coil 1
7 Oil seal 1
For installation, reverse the removal proce-
dure.

5-39
 STARTER CLUTCH AND GENERATOR (YP125R)

Removing the generator rotor and starter clutch

13 Nm (1.3 m•kgf, 9.4 ft•Ibf)

T.R
.
6 LT
LT

(3) E

5
E

M
8
4

E
3 E
E 2

New 1 80 Nm (8.0 m•kgf, 58 ft•Ibf)

T.R
.

Order Job/Parts to remove Q’ty Remarks

1 Circlip 1
2 Washer 1
3 Starter clutch idle gear shaft 1
4 Starter clutch idle gear 1
5 Generator rotor 1
6 Woodruff key 1
7 Starter clutch gear 1
8 Starter clutch 1
For installation, reverse the removal proce-
dure.

5-40
 STARTER CLUTCH AND GENERATOR (YP125R)

EAS37P1039

REMOVING THE GENERATOR

1. Remove:
• Generator cover
TIP
Loosen each bolt 1/4 of a turn at a time, in stag-
es and in a crisscross pattern. After all of the
bolts are fully loosened, remove them.
2. Remove:
• Generator rotor nut “1”
• Washer EAS37P1040

REMOVING THE STARTER CLUTCH

TIP
1. Remove:
• While holding the generator rotor “2” with the • Starter clutch bolts “1”
sheave holder “3”, loosen the generator rotor • Starter clutch
nut.
TIP
• Do not allow the sheave holder to touch the
projection on the generator rotor. • While holding the generator rotor “2” with the
sheave holder “3”, remove the starter clutch
bolts.
Sheave holder • Do not allow the sheave holder to touch the
90890-01701
projection on the generator rotor.
Primary clutch holder
YS-01880-A
Sheave holder
90890-01701
Primary clutch holder
YS-01880-A
1
1
2

3. Remove:
• Generator rotor “1” 3
(with the flywheel puller “2”) 2
• Woodruff key
ECA37P1005 EAS37P1041

NOTICE CHECKING THE STARTER CLUTCH

To protect the end of the crankshaft, place an 1. Check:
appropriate sized socket between the fly- • Starter clutch rollers “1”
wheel puller set center bolt and the crank- • Starter clutch spring caps “2”
shaft. • Starter clutch springs “3”
Damage/wear → Replace.
TIP
Make sure the flywheel puller is centered over
the generator rotor.

Flywheel puller
90890-01362
Heavy duty puller
YU-33270-B

5-41
 STARTER CLUTCH AND GENERATOR (YP125R)

2 TIP
3
1 • While holding the generator rotor “2” with the
sheave holder “3”, tighten the starter clutch
bolts.
3 • Do not allow the sheave holder to touch the
projection on the generator rotor.
1 2
2 Sheave holder
3 1 90890-01701
Primary clutch holder
2. Check: YS-01880-A
• Starter clutch idle gear
• Starter clutch gear
Burrs/chips/roughness/wear → Replace the 1
defective part(s).
3. Check:
• Starter clutch gear contact surfaces
Damage/pitting/wear → Replace the starter
clutch gear.
4. Check: 3
• Starter clutch operation 2
▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼
a. Install the starter clutch gear “1” onto the
EAS37P1043
starter clutch and hold the generator rotor. INSTALLING THE GENERATOR
b. When turning the starter clutch gear clock- 1. Install:
wise “A”, the starter clutch and the starter • Starter clutch gear
clutch gear should turn freely, otherwise the • Woodruff key
starter clutch is faulty and must be replaced. • Generator rotor
c. When turning the starter clutch gear counter- • Washer
clockwise “B”, it should engage, otherwise • Generator rotor nut
the starter clutch is faulty and must be re-
TIP
placed.
• Clean the tapered portion of the crankshaft and
the generator rotor hub.
A
1 • When installing the generator rotor, make sure
the woodruff key is properly seated in the key-
way of the crankshaft.
B • Lubricate the crankshaft end threads with en-
gine oil.
• Make sure that the blunt-edged corner of the
washer is facing outward.
2. Tighten:
▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲ • Generator rotor nut “1”
EAS37P1042

INSTALLING THE STARTER CLUTCH Generator rotor nut

1. Install: 80 Nm (8.0 m·kgf, 58 ft·lbf)
T.
R.

• Starter clutch
• Starter clutch bolts “1” TIP
• While holding the generator rotor “2” with the
Starter clutch bolt sheave holder “3”, tighten the generator rotor
13 Nm (1.3 m·kgf, 9.4 ft·lbf) nut.
T.
R.

LOCTITE® • Do not allow the sheave holder to touch the

projection on the generator rotor.

5-42
 STARTER CLUTCH AND GENERATOR (YP125R)

Sheave holder Generator cover bolt

90890-01701 10 Nm (1.0 m·kgf, 7.2 ft·lbf)

T.
R.
Primary clutch holder
YS-01880-A TIP
Tighten the generator cover bolts in stages and
in a crisscross pattern.

3. Apply:
• Sealant
(onto the crankshaft position sensor/stator
assembly lead grommet)

Yamaha bond No. 1215

90890-85505
(Three Bond No.1215®)

4. Install:
• Oil seal “1” New

Oil seal installed depth

4.5–5.4 mm (0.18–0.21 in)

New 1

a. Oil seal installed depth

5. Install:
• Generator cover

5-43
 ELECTRIC STARTER (YP125R)

EAS37P1044

ELECTRIC STARTER (YP125R)

Removing the starter motor

2
1 3

7 Nm (0.7 m•kgf, 5.1 ft•Ibf)

T.R
.

Order Job/Parts to remove Q’ty Remarks

Refer to “GENERAL CHASSIS” on page
Storage box/Air filter case 4-1.
1 Starter motor lead 1 Disconnect.
2 Ground lead 1 Disconnect.
3 Starter motor 1
For installation, reverse the removal proce-
dure.

5-44
 ELECTRIC STARTER (YP125R)

Disassembling the starter motor

LS

1 New 8

6
7
3 New

6
2
7

New

Order Job/Parts to remove Q’ty Remarks

1 O-ring 1
2 Starter motor yoke 1
3 O-ring 1
4 Armature assembly 1
5 Shim *
6 Brush 2
7 Spring 2
8 Front bracket/brush holder set 1
For assembly, reverse the disassembly pro-
cedure.

5-45
 ELECTRIC STARTER (YP125R)

EAS37P1045

CHECKING THE STARTER MOTOR Digital circuit tester

1. Check: 90890-03174
• Commutator Model 88 Multimeter with ta-
Dirt → Clean with 600 grit sandpaper. chometer
2. Measure: YU-A1927
• Commutator diameter “a”
Out of specification → Replace the starter
Armature coil
motor.
Commutator resistance “1”
Limit Continuity (0.0378–0.0462 Ω at
16.6 mm (0.65 in) 20 °C (68 °F))
Insulation resistance “2”
No continuity (Above 1 MΩ at 20
°C (68 °F))

3. Measure:
• Mica undercut “a”
Out of specification → Scrape the mica to the b. If any resistance is out of specification, re-
proper measurement with a hacksaw blade place the starter motor.
that has been grounded to fit the commutator.
▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲

Mica undercut (depth) 5. Measure:

1.35 mm (0.05 in) • Brush length “a”
Out of specification → Replace the brushes
TIP as a set.
The mica of the commutator must be undercut to
Limit
ensure proper operation of the commutator.
3.50 mm (0.14 in)

4. Measure:
• Armature assembly resistances (commutator 6. Measure:
and insulation) • Brush spring force
Out of specification → Replace the starter Out of specification → Replace the brush
motor. springs as a set.
▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼
a. Measure the armature assembly resistances Brush spring force
with the digital circuit tester. 3.92–5.88 N (400–600 gf, 14.11–
21.17 oz)

5-46
 ELECTRIC STARTER (YP125R)

7. Check:
• Gear teeth
Damage/wear → Replace the gear.
8. Check:
• Bearing
• Oil seal
• Bushing
Damage/wear → Replace the defective
part(s).

5-47
 OIL PUMP (YP125R)

EAS37P1046

OIL PUMP (YP125R)

Removing the oil pump

3
6
7
8
4
5

4 Nm (0.4 m•kgf, 2.9 ft•Ibf)

T.R
.

1
LT

12 Nm (1.2 m•kgf, 8.7 ft•Ibf)

T.R
.

Order Job/Parts to remove Q’ty Remarks

Refer to “STARTER CLUTCH AND GENER-
Starter clutch gear ATOR (YP125R)” on page 5-39.
1 Oil pump plate 1
2 Oil pump assembly 1
3 Oil pump housing cover 1
4 Pin 1
5 Oil pump driven gear 1
6 Oil pump inner rotor 1
7 Oil pump outer rotor 1
8 Oil pump housing 1
For installation, reverse the removal proce-
dure.

5-48
 OIL PUMP (YP125R)

EAS37P1047

CHECKING THE OIL PUMP Inner-rotor-to-outer-rotor-tip

1. Check: clearance
• Oil pump drive gear Less than 0.15 mm (0.0059 in)
• Oil pump driven gear Limit
• Oil pump housing 0.23 mm (0.0091 in)
• Oil pump housing cover Outer-rotor-to-oil-pump-housing
Cracks/damage/wear → Replace the defec- clearance
tive part(s). 0.013–0.018 mm (0.0005–0.0007
2. Measure: in)
Limit
• Inner-rotor-to-outer-rotor-tip clearance “a”
0.25 mm (0.0098 in)
• Outer-rotor-to-oil-pump-housing clearance Oil-pump-housing-to-inner-and-
“b” outer-rotor clearance
• Oil-pump-housing-to-inner-rotor-and-outer- 0.06–0.11 mm (0.0024–0.0043 in)
rotor clearance “c” Limit
Out of specification → Replace the oil pump. 0.18 mm (0.0071 in)

3. Check:
• Oil pump operation
Rough movement → Repeat steps (1) and
(2) or replace the defective part(s).

EAS37P1048

ASSEMBLING THE OIL PUMP

1. Lubricate:
• Inner rotor
• Outer rotor

1. Inner rotor
Recommended lubricant
Engine oil
2. Outer rotor
3. Oil pump housing 2. Lubricate:
• Oil pump shaft
(with the recommended lubricant)

Recommended lubricant
Molybdenum disulfide grease

3. Install:
• Oil pump driven gear
• Oil pump housing “1”
• Oil pump outer rotor “2”
• Oil pump inner rotor “3”
• Pin “4”
• Oil pump housing cover

5-49
 OIL PUMP (YP125R)

TIP
When installing the inner rotor, align the pin “4”
in the oil pump driven gear with the groove “a” in
the inner rotor.

4 3

2
a
1

4. Check:
• Oil pump operation
Refer to “CHECKING THE OIL PUMP” on
page 5-49.
EAS37P1049

INSTALLING THE OIL PUMP

1. Install:
• Oil pump assembly

Oil pump assembly screw

4 Nm (0.4 m·kgf, 2.9 ft·lbf)
T.
R.

ECA37P1006

NOTICE
After tightening the screws, make sure the
oil pump turns smoothly.

5-50
 TRANSMISSION (YP125R)

EAS37P1050

TRANSMISSION (YP125R)
Removing the transmission

3 New E

LS

New
11 E
10 8B
3 9 7
6A
5 E

4 New
New 2
E
1 (6)
LS
A 6 5 B 8
9 E 16 Nm (1.6 m•kgf, 11 ft•Ibf)
T.R

11
.

Order Job/Parts to remove Q’ty Remarks

Rear wheel Refer to “REAR WHEEL” on page 4-15.
Drain.
Final transmission oil Refer to “CHANGING THE FINAL TRANS-
MISSION OIL” on page 3-14.
Refer to “V-BELT AUTOMATIC TRANSMIS-
Secondary sheave assembly SION (YP125R)” on page 5-30.
1 Transmission case cover 1
2 Gasket 1
3 Dowel pin 2
4 Primary drive gear 1
5 Washer 1
6 Conical spring washer 1
7 1st wheel gear 1
8 Conical spring washer 1
9 Main axle/primary driven gear 1
10 Washer 1

5-51
 TRANSMISSION (YP125R)

Removing the transmission

3 New E

LS

New
11 E
10 8B
3 9 7
6A
5 E

4 New
New 2
E
1 (6)
LS
A 6 5 B 8
9 E 16 Nm (1.6 m•kgf, 11 ft•Ibf)
T.R

11
.

Order Job/Parts to remove Q’ty Remarks

11 Drive axle 1
For installation, reverse the removal proce-
dure.

5-52
 TRANSMISSION (YP125R)

EAS37P1051

REMOVING THE TRANSMISSION

1. Remove:
• Transmission case cover
TIP
Loosen each bolt 1/4 of a turn at a time, in stag-
es and in a crisscross pattern. After all of the
bolts are fully loosened, remove them.

EAS37P1052

CHECKING THE TRANSMISSION

1. Check:
• Transmission gears
Blue discoloration/pitting/wear → Replace
the defective gear(s).
• Transmission gear dogs
Cracks/damage/rounded edges → Replace
the defective gear(s).
2. Check:
• Transmission gear engagement
(each pinion gear to its respective wheel
gear)
Incorrect → Reassemble the transmission
axle assemblies.
3. Check:
• Transmission gear movement
Rough movement → Replace the defective
part(s).
EAS37P1053

INSTALLING THE TRANSMISSION

1. Install:
• Oil seal “1”
• Oil seal “2”

Oil seal installed depth

0–0.5 mm (0–0.020 in)

1
a. Oil seal installed depth

5-53
 CRANKSHAFT (YP125R)

EAS37P1054

CRANKSHAFT (YP125R)
Removing the crankshaft

11
9 E

13 14
20 Nm (2.0 m•kgf, 14 ft•Ibf)

T.R
.
12
LS New
New
8
E
5 9
E

4 LS
New
LS
7 (3)
3 6
(5)
New
10 New
15 New
2

10 Nm (1.0 m•kgf, 7.2 ft•Ibf) 1

T.R
.

LS (3)
New
32 Nm (3.2 m•kgf, 23 ft•Ibf)
T.R

10 Nm (1.0 m•kgf, 7.2 ft•Ibf)

.

T.R
.

20 Nm (2.0 m•kgf, 14 ft•Ibf)

T.R
.

7 Nm (0.7 m•kgf, 5.1 ft•Ibf)

T.R
.

Order Job/Parts to remove Q’ty Remarks

Refer to “ENGINE REMOVAL (YP125R)” on
Engine page 5-1.
Refer to “CYLINDER HEAD (YP125R)” on
Cylinder head page 5-7.
Refer to “CYLINDER AND PISTON
Piston (YP125R)” on page 5-25.
Refer to “V-BELT AUTOMATIC TRANSMIS-
Belt drive SION (YP125R)” on page 5-30.
Refer to “OIL PUMP (YP125R)” on page
Oil pump assembly 5-48.
Refer to “TRANSMISSION (YP125R)” on
Transmission page 5-51.
1 Oil filter element cover 1
2 Oil filter element 1
3 Oil strainer cover 1
4 Spring 1
5 Oil strainer 1
6 Timing chain guide retaining bolt 1

5-54
 CRANKSHAFT (YP125R)

Removing the crankshaft

11
9 E

13 14
20 Nm (2.0 m•kgf, 14 ft•Ibf)

T.R
.
12
LS New
New
8
E
5 9
E

4 LS
New
LS
7 (3)
3 6
(5)
New
10 New
15 New
2

10 Nm (1.0 m•kgf, 7.2 ft•Ibf) 1

T.R
.

LS (3)
New
32 Nm (3.2 m•kgf, 23 ft•Ibf)
T.R

10 Nm (1.0 m•kgf, 7.2 ft•Ibf)

.

T.R
.

20 Nm (2.0 m•kgf, 14 ft•Ibf)

T.R
.

7 Nm (0.7 m•kgf, 5.1 ft•Ibf)

T.R
.

Order Job/Parts to remove Q’ty Remarks

7 Timing chain guide (intake side) 1
8 Left crankcase 1
9 Dowel pin 2
10 Timing chain 1
11 Right crankcase 1
12 Crankshaft assembly 1
13 Oil pump drive gear 1
14 Bearing 1
15 Oil seal 1
For installation, reverse the removal proce-
dure.

5-55
 CRANKSHAFT (YP125R)

EAS37P1055 ECA37P1008

DISASSEMBLING THE CRANKCASE NOTICE

1. Remove: • To protect the end of the crankshaft, place
• Crankcase bolts an appropriate sized socket “4” between
TIP the crankcase separating tool bolt and the
Loosen each bolt 1/4 of a turn at a time, in stag- crankshaft.
es and in a crisscross pattern. After all of the • Do not tap on the crankshaft.
bolts are fully loosened, remove them.
Crankcase separating tool
90890-01135
Crankcase separator
YU-01135-B

2. Remove: 1
• Left crankcase “1” 4
ECA37P1007
3 2
NOTICE
Tap on one side of the crankcase with a soft-
EAS37P1057
face hammer. Tap only on the reinforced por- CHECKING THE TIMING CHAIN AND TIMING
tions of the crankcase, not on the crankcase CHAIN GUIDE
mating surfaces. Work slowly and carefully, 1. Check:
and make sure the crankcase halves sepa- • Timing chain
rate evenly. Damage/stiffness → Replace the timing
chain and camshaft sprocket as a set.

EAS37P1056

REMOVING THE CRANKSHAFT ASSEMBLY 2. Check:

1. Remove: • Timing chain guide (intake side)
• Crankshaft assembly “1” Damage/wear → Replace.
TIP EAS37P1058

• Remove the crankshaft assembly with the CHECKING THE CRANKSHAFT AND
crankcase separating tool “2” and M6 bolts “3”. CONNECTING ROD
• Make sure that the crankcase separating tool 1. Measure:
is centered over the crankshaft assembly. • Crankshaft runout
Out of specification → Replace the crank-
shaft.
TIP
Turn the crankshaft slowly.

5-56
 CRANKSHAFT (YP125R)

• Bearing “2”
Runout limit C Cracks/damage/wear → Replace the crank-
0.030 mm (0.0012 in) shaft.

5. Check:
2. Measure:
• Crankshaft journal
• Big end side clearance
Scratches/wear → Replace the crankshaft.
Out of specification → Replace the crank-
• Crankshaft journal oil passage
shaft.
Obstruction → Blow out with compressed air.
Big end side clearance D
0.150–0.450 mm (0.0059–0.0177
in)

EAS37P1059

CHECKING THE CRANKCASE

1. Thoroughly wash the crankcase halves in a
mild solvent.
3. Measure: 2. Thoroughly clean all the gasket surfaces and
• Crankshaft width crankcase mating surfaces.
Out of specification → Replace the crank- 3. Check:
shaft. • Crankcase
Cracks/damage → Replace.
Width A • Oil delivery passages
45.95–46.00 mm (1.809–1.811 in) Obstruction → Blow out with compressed air.
EAS37P1060

CHECKING THE BEARING AND OIL SEAL

1. Check:
• Bearing
Clean and lubricate the bearings, and then
rotate the inner race with your finger.
Rough movement → Replace.
EAS37P1061

CHECKING THE OIL PUMP DRIVE GEAR

1. Check:
4. Check: • Oil pump drive gear
• Crankshaft sprocket “1” Damage/wear → Replace.
Damage/wear → Replace the crankshaft.

5-57
 CRANKSHAFT (YP125R)

EAS37P1062

CHECKING THE OIL STRAINERS Crankshaft installer pot

1. Check: 90890-01274
• Oil strainers Installing pot
Damage → Replace. YU-90058
Contaminants → Clean with solvent. Crankshaft installer bolt
90890-01275
EAS37P1063
Bolt
INSTALLING THE CRANKSHAFT YU-90060
1. Lubricate: Adapter (M14)
• Oil seals 90890-01478
• Bearings Adapter #6
• Oil pump drive gear YM-90066
Fork seal driver attachment
Recommended lubricant 90890-01186
Oil seal Replacement 27 mm
Lithium-soap-based grease YM-A9409-1
Bearing, oil pump drive gear
Engine oil
5
2. Install:
• Oil seal “1” 4
(to the left crankcase) 2
1
Oil seal installed depth
0–0.5 mm (0–0.020 in) 3

ECA13970

NOTICE
To avoid scratching the crankshaft and to
a ease the installation procedure, lubricate the
1 oil seal lips with lithium-soap-based grease
and each bearing with engine oil.
TIP
Hold the connecting rod at top dead center
a. Oil seal installed depth (TDC) with one hand while turning the nut of the
3. Install: crankshaft installer bolt with the other. Turn the
• Bearing crankshaft installer bolt until the crankshaft as-
(to the right crankcase) sembly bottoms against the bearing.
4. Install: 5. Install:
• Crankshaft assembly “1” • Oil pump drive gear “1”
TIP TIP
• Install the crankshaft assembly with the crank- Install the oil pump drive gear with the crankshaft
shaft installer pot “2”, crankshaft installer bolt installer pot “2”, crankshaft installer bolt “3”, and
“3”, adapter “4”, and fork seal driver attachment adapter “4”.
“5”.
• The fork seal driver attachment should only
contact the inner race of the bearing.

5-58
 CRANKSHAFT (YP125R)

TIP
Crankshaft installer pot
90890-01274 After installing the left crankcase, make sure that
Installing pot the timing chain is securely meshed with the
YU-90058 crankshaft sprocket.
Crankshaft installer bolt
90890-01275
Bolt
YU-90060
Adapter (M14)
90890-01478
Adapter #6
YM-90066
1 2

4. Install:
1 • Crankcase bolts

Crankcase bolt
T.
10 Nm (1.0 m·kgf, 7.2 ft·lbf)
R.
3
2 4 TIP
Tighten the crankcase bolts in stages and in a
EAS37P1064
crisscross pattern.
ASSEMBLING THE CRANKCASE
• M6 × 110 mm (4.33 in) bolts: “1”
1. Thoroughly clean all the gasket mating sur-
• M6 × 80 mm (3.15 in) bolts: “2”
faces and crankcase mating surfaces.
• M6 × 70 mm (2.76 in) bolts: “3”
2. Apply:
• Sealant 3 2
(onto the crankcase mating surfaces) 1

Yamaha bond No. 1215

90890-85505
(Three Bond No.1215®)
2 3
TIP
Do not allow any sealant to come into contact 1
1
with the oil gallery.
5. Install:
• Oil filter element cover “1”

Oil filter element cover

10 Nm (1.0 m·kgf, 7.2 ft·lbf)
T.
R.

TIP
Be sure to face the “ ” mark “a” on the oil filter
element cover in the direction shown in the illus-
tration.

3. Install:
• Timing chain “1”
• Left crankcase “2”

5-59
 CRANKSHAFT (YP125R)

5-60
 ENGINE REMOVAL (YP250R)

EAS23710

ENGINE REMOVAL (YP250R)

Removing the muffler and exhaust pipe

1
45 Nm (4.5 m•kgf, 32 ft•Ibf)
T.R
.

4 New 6 New
2
5

65 Nm (6.5 m•kgf, 47 ft•Ibf)

T.R
.

14 Nm (1.4 m•kgf, 10 ft•Ibf) 20 Nm (2.0 m•kgf, 14 ft•Ibf)

T.R
.

T.R
.

Order Job/Parts to remove Q’ty Remarks

1 O2 sensor coupler 1 Disconnect.

2 O2 sensor 1

3 Muffler 1
4 Gasket 1
5 Exhaust pipe 1
6 Gasket 1
For installation, reverse the removal proce-
dure.

5-61
 ENGINE REMOVAL (YP250R)

Disconnecting the leads and hoses

7 Nm (0.7 m•kgf, 5.1 ft•Ibf)

T.R
.
3

8
2 7

1 6

Order Job/Parts to remove Q’ty Remarks

Drain.
Engine oil Refer to “CHANGING THE ENGINE OIL” on
page 3-27.
Drain.
Coolant Refer to “CHANGING THE COOLANT” on
page 3-32.
Refer to “GENERAL CHASSIS” on page
Air filter case 4-1.
Fuel injector assembly/Throttle body/Intake Refer to “THROTTLE BODY” on page 7-5.
manifold
1 Spark plug cap 1 Disconnect.
2 Coolant temperature sensor coupler 1 Disconnect.
Crankshaft position sensor/stator assembly
3 2 Disconnect.
coupler
4 Radiator inlet hose 1 Disconnect.
5 Radiator outlet hose 1 Disconnect.
6 Cylinder head breather hose 1
7 Starter motor lead 1 Disconnect.

5-62
 ENGINE REMOVAL (YP250R)

Disconnecting the leads and hoses

7 Nm (0.7 m•kgf, 5.1 ft•Ibf)

T.R
.
3

8
2 7

1 6

Order Job/Parts to remove Q’ty Remarks

8 Ground lead 1 Disconnect.
For installation, reverse the removal proce-
dure.

5-63
 ENGINE REMOVAL (YP250R)

Removing the engine

8 59 Nm (5.9 m•kgf, 43 ft•Ibf)

T.R
.
9
8
5
32 Nm (3.2 m•kgf, 23 ft•Ibf)

T.R
.
43 Nm (4.3 m•kgf, 31 ft•Ibf)
T.R
.

2
3
4
18 Nm (1.8 m•kgf, 13 ft•Ibf)
1

T.R
6

.
5

64 Nm (6.4 m•kgf, 46 ft•Ibf) 5

6
T.R
.

64 Nm (6.4 m•kgf, 46 ft•Ibf)

T.R
.

Order Job/Parts to remove Q’ty Remarks

Refer to “REAR SHOCK ABSORBER AS-
Rear brake caliper SEMBLIES AND SWINGARM” on page
4-61.

TIP
Place a suitable stand under the engine.

1 Mudguard 1
2 Rear shock absorber 2
3 Engine mounting nut/washer/bolt 1/1/1
4 Spacer 1
5 Engine bracket rod nut/washer/bolt 2/2/2
6 Engine bracket rod 2
7 Engine 1
8 Engine bracket nut/bolt 2/2
9 Engine bracket 1
For installation, reverse the removal proce-
dure.

5-64
 ENGINE REMOVAL (YP250R)

EAS23720

INSTALLING THE ENGINE 7 2

1. Install:
• Engine “1”
• Engine bracket “2” 7
• Engine bracket rods “3” 6
• Spacer “4”
• Engine mounting nut/washer/bolt “5”
• Engine bracket rod bolts/washers/nuts “6” 7
• Engine bracket nuts/bolts “7”
• Rear shock absorber assemblies “8” 6
TIP 8
• Do not fully tighten the bolts and nuts. 5
4
• Be sure to install each engine bracket rod “3”
with the white mark “a” on the rod facing for-
ward. 3
6
1 3
5
6

a
3. Tighten:
• Rear shock absorber assembly upper nuts
• Rear shock absorber assembly lower bolts
3 Rear shock absorber assembly
2. Tighten: upper nut
T.
R.

• Engine bracket rod nuts “6” 32 Nm (3.2 m·kgf, 23 ft·lbf)

Rear shock absorber assembly
• Engine mounting nut “5”
lower bolt
• Engine bracket nuts “7” 18 Nm (1.8 m·kgf, 13 ft·lbf)
Engine bracket rod nut
4. Install:
64 Nm (6.4 m·kgf, 46 ft·lbf)
T.
R.

Engine mounting nut • Gasket New

43 Nm (4.3 m·kgf, 31 ft·lbf) • Exhaust pipe
Engine bracket nut • Exhaust pipe nuts
59 Nm (5.9 m·kgf, 43 ft·lbf) (temporarily tighten)
5. Install:
• Muffler
• Muffler mounting bolts
(temporarily tighten)
TIP
Install the muffler mounting bolts in the proper in-
stalling sequence as shown.
6. Tighten:
• Muffler mounting bolts

Muffler mounting bolt

65 Nm (6.5 m·kgf, 47 ft·lbf)
T.
R.

5-65
 ENGINE REMOVAL (YP250R)

TIP
Tighten the muffler mounting bolts in the proper
tightening sequence as shown.

2
3

7. Tighten:
• Exhaust pipe nuts

Exhaust pipe nut

20 Nm (2.0 m·kgf, 14 ft·lbf)
T.
R.

8. Tighten:
• Muffler joint bolt
• O2 sensor

Muffler joint bolt

14 Nm (1.4 m·kgf, 10 ft·lbf)
T.
R.

O2 sensor
45 Nm (4.5 m·kgf, 32 ft·lbf)

5-66
 CYLINDER HEAD (YP250R)

EAS24100

CYLINDER HEAD (YP250R)

Removing the cylinder head
New 1 18 Nm (1.8 m•kgf, 13 ft•Ibf)
10 Nm (1.0 m•kgf, 7.2 ft•Ibf)

T.R
.
T.R
.

7 60 Nm (6.0 m•kgf, 43 ft•Ibf)

T.R
.
13
LS

E New

22 Nm (2.2 m•kgf, 16 ft•Ibf) 5

12
T.R
.

(4) 11
10
New
18 Nm (1.8 m•kgf, 13 ft•Ibf) 6
T.R
.

10 Nm (1.0 m•kgf, 7.2 ft•Ibf)

T.R
.

7 Nm (0.7 m•kgf, 5.1 ft•Ibf) New New

T.R
.

8 Nm (0.8 m•kgf, 5.8 ft•Ibf) 7

T.R
.

2
LS
8 LS
4 10 Nm (1.0 m•kgf, 7.2 ft•Ibf)
New New T.R
.

9 New 10 Nm (1.0 m•kgf, 7.2 ft•Ibf)

T.R
LS
.

New 14 3
15
Order Job/Parts to remove Q’ty Remarks
Refer to “THERMOSTAT (YP250R)” on page
Thermostat 6-10.
Refer to “ENGINE REMOVAL (YP250R)” on
Engine page 5-61.
1 Coolant temperature sensor 1
2 Oil check bolt 1
3 V-belt case air filter cover 1
4 Timing mark accessing plug 1
5 Spark plug 1
6 Camshaft sprocket cover 1
7 Tappet cover 2
8 Timing chain tensioner 1
9 Timing chain tensioner gasket 1
10 Camshaft sprocket plate 1
11 Camshaft sprocket 1
12 Dowel pin 1
13 Cylinder head 1

5-67
 CYLINDER HEAD (YP250R)

Removing the cylinder head

New 1 18 Nm (1.8 m•kgf, 13 ft•Ibf)
10 Nm (1.0 m•kgf, 7.2 ft•Ibf)

T.R
.
T.R
.

7 60 Nm (6.0 m•kgf, 43 ft•Ibf)

T.R
.
13
LS

E New

22 Nm (2.2 m•kgf, 16 ft•Ibf) 5

12
T.R
.

(4) 11
10
New
18 Nm (1.8 m•kgf, 13 ft•Ibf) 6
T.R
.

10 Nm (1.0 m•kgf, 7.2 ft•Ibf)

T.R
.

7 Nm (0.7 m•kgf, 5.1 ft•Ibf) New New

T.R
.

8 Nm (0.8 m•kgf, 5.8 ft•Ibf) 7

T.R
.

2
LS
8 LS
4 10 Nm (1.0 m•kgf, 7.2 ft•Ibf)
New New

T.R
.
9 New 10 Nm (1.0 m•kgf, 7.2 ft•Ibf)

T.R
LS

New 14 3
15
Order Job/Parts to remove Q’ty Remarks
14 Cylinder head gasket 1
15 Dowel pin 2
For installation, reverse the removal proce-
dure.

5-68
 CYLINDER HEAD (YP250R)

EAS24130
• Camshaft sprocket bolt “1”
REMOVING THE CYLINDER HEAD
• Camshaft sprocket plate “2”
1. Align:
• Camshaft sprocket
• “I” mark “a” on the generator rotor
(with the stationary pointer “b” on the genera- TIP
tor cover) To prevent the timing chain from falling into the
▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼ crankcase, fasten it with a wire “3”.
a. Turn the primary sheave nut on the left side
of the crankshaft counterclockwise to turn the
crankshaft.

1
2
3

4. Remove:
• Cylinder head
TIP
b. When the piston is at TDC on the compres-
sion stroke, align the “I” mark “c” on the cam- • Loosen the bolts and nuts in the proper se-
shaft sprocket with the stationary pointer “d” quence as shown.
on the cylinder head. • Loosen each bolt and nut 1/2 of a turn at a
time. After all of the bolts and nuts are fully
loosened, remove them.

▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲
2. Loosen:
• Camshaft sprocket bolt “1” EAS24160

TIP CHECKING THE CYLINDER HEAD

While holding the primary sheave nut with a 1. Eliminate:
wrench, remove the camshaft sprocket bolt. • Combustion chamber carbon deposits
(with a rounded scraper)
TIP
1
Do not use a sharp instrument to avoid damag-
ing or scratching:
• Spark plug bore threads
• Valve seats

3. Remove:
• Timing chain tensioner
(along with the gasket)

5-69
 CYLINDER HEAD (YP250R)

TIP
To ensure an even surface, rotate the cylinder
head several times.
▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲
EAS23870

CHECKING THE CAMSHAFT SPROCKET

1. Check:
• Camshaft sprocket
More than 1/4 tooth wear “a” → Replace the
2. Check: camshaft sprocket, timing chain and crank-
• Cylinder head shaft as a set.
Damage/scratches → Replace.
• Cylinder head water jacket
Mineral deposits/rust → Eliminate.
3. Measure:
• Cylinder head warpage
Out of specification → Resurface the cylinder
head.

Warpage limit
0.05 mm (0.0020 in)
a. 1/4 tooth
▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼
a. Place a straightedge “1” and a thickness b. Correct
gauge “2” across the cylinder head. 1. Timing chain roller
2. Camshaft sprocket
EAS24190

CHECKING THE TIMING CHAIN TENSIONER

1. Check:
• Timing chain tensioner
Cracks/damage → Replace.
2. Check:
• One-way cam operation
Rough movement → Replace the timing
chain tensioner housing.

1 2

b. Measure the warpage. 3. Check:

c. If the limit is exceeded, resurface the cylinder • Cap bolt
head as follows. • Spring
d. Place 400–600 grit wet sandpaper on the sur- • One-way cam
face plate and resurface the cylinder head • Timing chain tensioner rod
using a figure-eight sanding pattern. Damage/wear → Replace the defective
part(s).

5-70
 CYLINDER HEAD (YP250R)

EAS24230

INSTALLING THE CYLINDER HEAD

1. Tighten:
• Cylinder head nuts “1”

Cylinder head nut

22 Nm (2.2 m·kgf, 16 ft·lbf)
T.
R.

• Cylinder head bolts “2”

Cylinder head bolt

10 Nm (1.0 m·kgf, 7.2 ft·lbf)
T.
R.

TIP
• Lubricate the cylinder head nuts and washers
with engine oil.
• Tighten the cylinder head nuts and bolts in the
proper tightening sequence as shown and
torque them in two stages.

d. Install the timing chain onto the camshaft

sprocket, and then install the camshaft
sprocket onto the camshaft.
TIP
• When installing the camshaft sprocket, be sure
to keep the timing chain as tight as possible on
the exhaust side.
• Align the dowel pin “1” on the camshaft with the
2. Install: slot in the camshaft sprocket.
• Dowel pin “1” ECA37P1009
• Camshaft sprocket “2” NOTICE
• Timing chain “3”
Do not turn the crankshaft when installing
• Camshaft sprocket plate
the camshaft to avoid damage or improper
• Washer
valve timing.
• Camshaft sprocket bolt
▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼ e. Install the camshaft sprocket plate and cam-
a. Turn the primary sheave nut on the left side shaft sprocket bolt.
of the crankshaft counterclockwise to turn the f. While holding the primary sheave nut, tempo-
crankshaft. rarily tighten the camshaft sprocket bolt.
b. Align the “I” mark “a” on the generator rotor g. Remove the wire from the timing chain.
with the stationary pointer “b” on the genera- ▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲
tor cover. 3. Install:
c. Align the “I” mark “c” on the camshaft sprock-
et with the stationary pointer “d” on the cylin- • Timing chain tensioner gasket New
der head. • Timing chain tensioner
▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼
a. Remove the timing chain tensioner cap bolt
“1” and spring “2”.
b. Release the timing chain tensioner one-way
cam “3” and push the timing chain tensioner
rod “4” all the way into the timing chain ten-
sioner housing.

5-71
 CYLINDER HEAD (YP250R)

c. Install the timing chain tensioner and gasket ECA37P1010

“5” onto the cylinder. NOTICE

Be sure to tighten the camshaft sprocket bolt
Timing chain tensioner bolt to the specified torque to avoid the possibil-
10 Nm (1.0 m·kgf, 7.2 ft·lbf) ity of the bolt coming loose and damaging
T.
R.

the engine.
d. Install the spring and timing chain tensioner
cap bolt. 7. Measure:
• Valve clearance
Timing chain tensioner cap bolt Out of specification → Adjust.
8 Nm (0.8 m·kgf, 5.8 ft·lbf) Refer to “ADJUSTING THE VALVE CLEAR-
T.
R.

ANCE” on page 3-21.

1
2

3
5 New
4

▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲
4. Turn:
• Crankshaft
(turn the primary sheave nut on the left side
of the crankshaft several turns counterclock-
wise)
5. Check:
• “I” mark “a”
Make sure the “I” mark “a” on the generator
rotor is aligned with the stationary pointer “b”
on the generator cover.
• “I” mark “c”
Make sure the “I” mark “c” on the camshaft
sprocket is aligned with the stationary pointer
“d” on the cylinder head.
Out of alignment → Correct.
Refer to the installation steps above.

6. Tighten:
• Camshaft sprocket bolt

Camshaft sprocket bolt

60 Nm (6.0 m·kgf, 43 ft·lbf)
T.
R.

5-72
 CAMSHAFT (YP250R)

EAS23730

CAMSHAFT (YP250R)
Removing the rocker arms and camshaft

1 14 Nm (1.4 m•kgf, 10 ft•Ibf)

T.R
.
2 7 M

M
8
8 Nm (0.8 m•kgf, 5.8 ft•Ibf)

T.R
.
7 4
6 3 New

5
New
2 LS
1 M

14 Nm (1.4 m•kgf, 10 ft•Ibf) E E

T.R
.

Order Job/Parts to remove Q’ty Remarks

Refer to “CYLINDER HEAD (YP250R)” on
Cylinder head page 5-67.
1 Locknut 2 Loosen.
2 Adjusting screw 2 Loosen.
3 Lock plate 1
4 Camshaft retainer 1
5 Intake rocker arm shaft 1
6 Exhaust rocker arm shaft 1
7 Rocker arm 2
8 Camshaft 1
For installation, reverse the removal proce-
dure.

5-73
 CAMSHAFT (YP250R)

EAS23770

REMOVING THE ROCKER ARMS AND

CAMSHAFT
1. Straighten the lock plate tabs “a”.
2. Remove:
• Lock plate “1”
• Camshaft retainer “2”

EAS23840

CHECKING THE CAMSHAFT

1. Check:
• Camshaft lobes
Blue discoloration/pitting/scratches → Re-
place the camshaft.
2. Measure:
3. Remove: • Camshaft lobe dimensions “a” and “b”
• Rocker arm shafts Out of specification → Replace the camshaft.
• Rocker arms
TIP Camshaft lobe dimensions
Remove the rocker arm shafts with the slide Intake A
hammer bolt “1” and weight “2”. 37.051–37.151 mm (1.4587–
1.4626 in)
Limit
Slide hammer bolt 36.950 mm (1.4547 in)
90890-01083 Intake B
Slide hammer bolt 6 mm 30.074–30.174 mm (1.1840–
YU-01083-1 1.1880 in)
Weight Limit
90890-01084 29.974 mm (1.1801 in)
YU-01083-3 Exhaust A
37.053–37.153 mm (1.4588–
1.4627 in)
Limit
36.953 mm (1.4548 in)
Exhaust B
30.091–30.191 mm (1.1847–
1.1886 in)
Limit
29.991 mm (1.1807 in)

4. Remove:
• Camshaft “1”
TIP
Screw a M10 bolt “2” into the threaded end of the
camshaft, and then pull out the camshaft.

5-74
 CAMSHAFT (YP250R)

Rocker arm shaft outside diame-

ter
11.981–11.991 mm (0.4717–
0.4721 in)
Limit
11.950 mm (0.4705 in)

3. Check:
• Camshaft oil passage
Obstruction → Blow out with compressed air.
EAS23880

CHECKING THE ROCKER ARMS AND

ROCKER ARM SHAFTS
The following procedure applies to all of the
rocker arms and rocker arm shafts. 5. Calculate:
1. Check: • Rocker-arm-to-rocker-arm-shaft clearance
• Rocker arm TIP
Damage/wear → Replace. Calculate the clearance by subtracting the rock-
2. Check: er arm shaft outside diameter from the rocker
• Rocker arm shaft arm inside diameter.
Blue discoloration/excessive wear/pit-
Out of specification → Replace the defective
ting/scratches → Replace or check the lubri-
part(s).
cation system.
3. Measure: Rocker-arm-to-rocker-arm-shaft
• Rocker arm inside diameter “a” clearance
Out of specification → Replace. 0.009–0.037 mm (0.0004–0.0015
in)
Rocker arm inside diameter Limit
12.000–12.018 mm (0.4724– 0.080 mm (0.0031 in)
0.4731 in)
Limit EAS24040
12.030 mm (0.4736 in) INSTALLING THE CAMSHAFT AND ROCKER
ARMS
1. Lubricate:
• Camshaft

Recommended lubricant
Camshaft
Molybdenum disulfide grease
Camshaft bearing
Engine oil

2. Lubricate:
• Rocker arms
4. Measure:
• Rocker arm shafts
• Rocker arm shaft outside diameter “a”
Out of specification → Replace. Recommended lubricant
Rocker arm inner surface
Molybdenum disulfide grease
Rocker arm shaft
Engine oil

5-75
 CAMSHAFT (YP250R)

3. Install:
• Exhaust rocker arm
• Exhaust rocker arm shaft
TIP
Make sure the exhaust rocker arm shaft is com-
pletely pushed into the cylinder head.
4. Install:
• Intake rocker arm
• Intake rocker arm shaft “1”
TIP
Insert a guide stud (8 mm) “2” into the stud-bolt
hole in the cylinder head and install the intake
rocker arm shaft as shown.
ECA13780

NOTICE
Make sure the threaded part of the rocker
arm shaft faces out.

5. Install:
• Camshaft retainer “1”
• Lock plate “2” New

Camshaft retainer bolt

8 Nm (0.8 m·kgf, 5.8 ft·lbf)
T.
R.

TIP
Bend the lock plate tabs along a flat side of the
bolts “3”.

5-76
 VALVES AND VALVE SPRINGS (YP250R)

EAS24270

VALVES AND VALVE SPRINGS (YP250R)

Removing the valves and valve springs

1
2
M
4

3
7 New
8
10 New
9 New

6
M

M
9 New 8 3 4 2 1
10 New 7 New
5

Order Job/Parts to remove Q’ty Remarks

Refer to “CYLINDER HEAD (YP250R)” on
Cylinder head page 5-67.
Refer to “CAMSHAFT (YP250R)” on page
Rocker arms/Camshaft 5-73.
1 Valve cotter 4
2 Upper spring seat 2
3 Outer valve spring 2
4 Inner valve spring 2
5 Intake valve 1
6 Exhaust valve 1
7 Valve stem seal 2
8 Lower spring seat 2
9 Valve guide 2
10 Clip 2
For installation, reverse the removal proce-
dure.

5-77
 VALVES AND VALVE SPRINGS (YP250R)

EAS24280

REMOVING THE VALVES

The following procedure applies to all of the
valves and related components.
TIP
Before removing the internal parts of the cylinder
head (e.g., valves, valve springs, valve seats),
make sure the valves properly seal.
1. Check:
• Valve sealing
Leakage at the valve seat → Check the valve 3. Remove:
face, valve seat, and valve seat width. • Upper spring seat “1”
Refer to “CHECKING THE VALVE SEATS” • Outer valve spring “2”
on page 5-80. • Inner valve spring “3”
▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼
• Valve “4”
a. Pour a clean solvent “a” into the intake and • Valve stem seal “5”
exhaust ports. • Lower spring seat “6”
b. Check that the valves properly seal. TIP
TIP Identify the position of each part very carefully so
There should be no leakage at the valve seat “1”. that it can be reinstalled in its original place.

▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲ EAS24290

2. Remove: CHECKING THE VALVES AND VALVE

• Valve cotters “1” GUIDES
The following procedure applies to all of the
TIP
valves and valve guides.
Remove the valve cotters by compressing the 1. Measure:
valve spring with the valve spring compressor • Valve-stem-to-valve-guide clearance
and the valve spring compressor attachment “2”. Out of specification → Replace the valve
guide.
Valve spring compressor • Valve-stem-to-valve-guide clearance =
90890-04019 Valve guide inside diameter “a” -
YM-04019 Valve stem diameter “b”
Valve spring compressor attach-
ment
90890-04108
Valve spring compressor adapt-
er 22 mm
YM-04108

5-78
 VALVES AND VALVE SPRINGS (YP250R)

b. Install a new clip and new valve guide with

Valve-stem-to-valve-guide clear- the valve guide installer “2” and valve guide
ance (intake) remover “1”.
0.010–0.037 mm (0.0004–0.0015
in)
Limit
0.080 mm (0.0031 in)
Valve-stem-to-valve-guide clear-
ance (exhaust)
0.025–0.052 mm (0.0010–0.0020
in)
Limit
0.100 mm (0.0039 in)

c. After installing the valve guide, bore the valve

guide with the valve guide reamer “3” to ob-
tain the proper valve-stem-to-valve-guide
clearance.

TIP
After replacing the valve guide, reface the valve
seat.

Valve guide remover (ø6)

90890-04064
2. Replace: Valve guide remover (6.0 mm)
• Valve guide YM-04064-A
Valve guide installer (ø6)
TIP 90890-04065
To ease valve guide removal and installation, Valve guide installer (6.0 mm)
and to maintain the correct fit, heat the cylinder YM-04065-A
head to 100 °C (212 °F) in an oven. Valve guide reamer (ø6)
90890-04066
▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼
Valve guide reamer (6.0 mm)
a. Remove the valve guide with the valve guide
YM-04066
remover “1”.
▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲
3. Eliminate:
• Carbon deposits
(from the valve face and valve seat)
4. Check:
• Valve face
Pitting/wear → Grind the valve face.

5-79
 VALVES AND VALVE SPRINGS (YP250R)

• Valve stem end 2. Check:

Mushroom shape or diameter larger than the • Valve seat
body of the valve stem → Replace the valve. Pitting/wear → Replace the cylinder head.
5. Measure: 3. Measure:
• Valve margin thickness “a” • Valve seat width “a”
Out of specification → Replace the valve. Out of specification → Replace the cylinder
head.
Valve margin thickness D (intake)
0.80–1.20 mm (0.0315–0.0472 in) Valve seat width C (intake)
Valve margin thickness D (ex- 0.90–1.10 mm (0.0354–0.0433 in)
haust) Limit
0.80–1.20 mm (0.0315–0.0472 in) 1.6 mm (0.06 in)
Valve seat width C (exhaust)
0.90–1.10 mm (0.0354–0.0433 in)
Limit
1.6 mm (0.06 in)

6. Measure:
• Valve stem runout
Out of specification → Replace the valve.
TIP
▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼
• When installing a new valve, always replace a. Apply Mechanic’s blueing dye (Dykem) “b”
the valve guide. onto the valve face.
• If the valve is removed or replaced, always re-
place the valve stem seal.

Valve stem runout

0.010 mm (0.0004 in)

b. Install the valve into the cylinder head.

c. Press the valve through the valve guide and
onto the valve seat to make a clear impres-
sion.
d. Measure the valve seat width.
TIP
EAS24300

CHECKING THE VALVE SEATS Where the valve seat and valve face contacted
The following procedure applies to all of the one another, the blueing will have been re-
valves and valve seats. moved.
1. Eliminate: ▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲
• Carbon deposits 4. Lap:
(from the valve face and valve seat) • Valve face
• Valve seat

5-80
 VALVES AND VALVE SPRINGS (YP250R)

TIP
After replacing the cylinder head or replacing the
valve and valve guide, the valve seat and valve
face should be lapped.
▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼
a. Apply a coarse lapping compound “a” to the
valve face.
ECA13790

NOTICE
Do not let the lapping compound enter the
h. Install the valve into the cylinder head.
gap between the valve stem and the valve
i. Press the valve through the valve guide and
guide.
onto the valve seat to make a clear impres-
sion.
j. Measure the valve seat width again. If the
valve seat width is out of specification, reface
and lap the valve seat.
▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲
EAS24310

CHECKING THE VALVE SPRINGS

The following procedure applies to all of the
valve springs.
1. Measure:
b. Apply molybdenum disulfide oil onto the • Valve spring free length “a”
valve stem. Out of specification → Replace the valve
c. Install the valve into the cylinder head. spring.
d. Turn the valve until the valve face and valve
seat are evenly polished, and then clean off Inner spring
all of the lapping compound. Free length (intake)
TIP 38.10 mm (1.50 in)
Limit
For the best lapping results, lightly tap the valve 36.10 mm (1.42 in)
seat while rotating the valve back and forth be- Free length (exhaust)
tween your hands. 38.10 mm (1.50 in)
Limit
36.10 mm (1.42 in)
Outer spring
Free length (intake)
36.93 mm (1.45 in)
Limit
35.00 mm (1.38 in)
Free length (exhaust)
36.93 mm (1.45 in)
Limit
35.00 mm (1.38 in)
e. Apply a fine lapping compound to the valve
face and repeat the above steps.
f. After every lapping procedure, be sure to
clean off all of the lapping compound from the
valve face and valve seat.
g. Apply Mechanic’s blueing dye (Dykem) “b”
onto the valve face.

5-81
 VALVES AND VALVE SPRINGS (YP250R)

3. Measure:
• Valve spring tilt “a”
Out of specification → Replace the valve
spring.

Inner spring
Spring tilt (intake)
2.5°/1.7 mm
Spring tilt (exhaust)
2.5°/1.7 mm
Outer spring
2. Measure: Spring tilt (intake)
• Compressed valve spring force “a” 2.5°/1.6 mm
Out of specification → Replace the valve Spring tilt (exhaust)
spring. 2.5°/1.6 mm
Inner spring
Installed compression spring
force (intake)
76–88 N (7.75–8.97 kgf, 17.08–
19.78 lbf)
Installed compression spring
force (exhaust)
76–88 N (7.75–8.97 kgf, 17.08–
19.78 lbf)
Installed length (intake)
30.10 mm (1.19 in)
Installed length (exhaust) EAS24340

30.10 mm (1.19 in) INSTALLING THE VALVES

Outer spring The following procedure applies to all of the
Installed compression spring valves and related components.
force (intake) 1. Deburr:
115–133 N (11.73–13.56 kgf, • Valve stem end
25.85–29.90 lbf) (with an oil stone)
Installed compression spring
force (exhaust)
115–133 N (11.73–13.56 kgf,
25.85–29.90 lbf)
Installed length (intake)
31.60 mm (1.24 in)
Installed length (exhaust)
31.60 mm (1.24 in)

2. Lubricate:
• Valve stem “1”
• Valve stem seal “2”
(with the recommended lubricant)

Recommended lubricant
Molybdenum disulfide oil

b. Installed length

5-82
 VALVES AND VALVE SPRINGS (YP250R)

Valve spring compressor

90890-04019
YM-04019
Valve spring compressor attach-
ment
90890-04108
Valve spring compressor adapt-
er 22 mm
YM-04108

3. Install:
• Lower spring seat “1”
• Valve stem seal “2” New
• Valve “3”
• Inner valve spring “4”
• Outer valve spring “5”
• Upper spring seat “6”
(into the cylinder head)
TIP
• Make sure each valve is installed in its original 5. To secure the valve cotters onto the valve
place. stem, lightly tap the valve tip with a soft-face
• Install the valve springs with the larger pitch “a” hammer.
facing up. ECA13800

NOTICE
Hitting the valve tip with excessive force
could damage the valve.

b. Smaller pitch
4. Install:
• Valve cotters “1”
TIP
Install the valve cotters by compressing the
valve spring with the valve spring compressor
and the valve spring compressor attachment “2”.

5-83
 CYLINDER AND PISTON (YP250R)

EAS24350

CYLINDER AND PISTON (YP250R)

Removing the cylinder and piston

4 New

3 5

6 New

11
New 10 2
E 9

LS

8 7 6 New
1 LS

New E

7 Nm (0.7 m•kgf, 5.1 ft•Ibf) E

T.R
.

Order Job/Parts to remove Q’ty Remarks

Refer to “CYLINDER HEAD (YP250R)” on
Cylinder head page 5-67.
1 Water pump outlet pipe 1
2 Timing chain guide (exhaust side) 1
3 Cylinder 1
4 Cylinder gasket 1
5 Dowel pin 2
6 Clip 2
7 Piston pin 1
8 Piston 1
9 Top ring 1
10 2nd ring 1
11 Oil ring 1
For installation, reverse the removal proce-
dure.

5-84
 CYLINDER AND PISTON (YP250R)

EAS24380

REMOVING THE PISTON TIP

1. Remove: When removing a piston ring, open the end gap
• Piston pin clips “1” with your fingers and lift the other side of the ring
• Piston pin “2” over the piston crown.
• Piston “3”
ECA13810

NOTICE
Do not use a hammer to drive the piston pin
out.
TIP
• Before removing the piston pin clips, cover the
crankcase opening with a clean rag to prevent
them from falling into the crankcase.
• Before removing the piston pin, deburr the pis-
ton pin clip groove and the piston pin bore ar- EAS24390

ea. If both areas are deburred and the piston CHECKING THE CYLINDER AND PISTON
pin is still difficult to remove, remove it with the 1. Check:
piston pin puller set “4”. • Piston wall
• Cylinder wall
Vertical scratches → Rebore or replace the
Piston pin puller set cylinder, and replace the piston and piston
90890-01304 rings as a set.
Piston pin puller
2. Measure:
YU-01304
• Piston-to-cylinder clearance
▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼
a. Measure cylinder bore “C” with the cylinder
bore gauge.
TIP
Measure cylinder bore “C” by taking side-to-side
and front-to-back measurements of the cylinder.
Then, find the average of the measurements.

Bore
69.000–69.005 mm (2.7165–
2.7167 in)
Taper limit
0.030 mm (0.0012 in)
Out of round limit
0.030 mm (0.0012 in)

“C” = maximum of D1–D2

“T” = maximum of D1 or D2 - maximum of D5
or D6
“R” = maximum of D1, D3 or D5 - minimum of
2. Remove:
D2, D4 or D6
• Top ring
• 2nd ring
• Oil ring

5-85
 CYLINDER AND PISTON (YP250R)

EAS24430

CHECKING THE PISTON RINGS

1. Measure:
• Piston ring side clearance
Out of specification → Replace the piston
and piston rings as a set.
TIP
Before measuring the piston ring side clearance,
eliminate any carbon deposits from the piston
ring grooves and piston rings.
b. If out of specification, rebore or replace the
cylinder, and replace the piston and piston Piston ring
rings as a set. Top ring
c. Measure piston skirt diameter D “a” with the Ring side clearance
micrometer. 0.040–0.080 mm (0.0016–
0.0031 in)
Limit
0.130 mm (0.0051 in)
2nd ring
Ring side clearance
0.030–0.070 mm (0.0012–
0.0028 in)
Limit
0.130 mm (0.0051 in)

b. 5 mm (0.20 in) from the bottom edge of the

piston

Piston
Diameter D
68.965–68.980 mm (2.7152–
2.7157 in)

d. If out of specification, replace the piston and

piston rings as a set. 2. Install:
e. Calculate the piston-to-cylinder clearance • Piston ring
with the following formula. (into the cylinder)
• Piston-to-cylinder clearance = TIP
Cylinder bore “C” - Level the piston ring into the cylinder with the
Piston skirt diameter “D”
piston crown.

Piston-to-cylinder clearance
0.020–0.040 mm (0.0008–0.0016
in)
Limit
0.15 mm (0.0059 in)

f. If out of specification, rebore or replace the

cylinder, and replace the piston and piston
rings as a set.
▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲
a. 5 mm (0.20 in)

5-86
 CYLINDER AND PISTON (YP250R)

3. Measure: 3. Measure:
• Piston ring end gap • Piston pin bore diameter “b”
Out of specification → Replace the piston Out of specification → Replace the piston.
ring.
TIP
Piston pin bore inside diameter
17.004–17.015 mm (0.6694–
The oil ring expander spacer end gap cannot be 0.6699 in)
measured. If the oil ring rail gap is excessive, re- Limit
place all three piston rings. 17.045 mm (0.6711 in)

Piston ring
Top ring
End gap (installed)
0.15–0.30 mm (0.0059–0.0118
in)
Limit
0.55 mm (0.0217 in)
2nd ring
End gap (installed)
0.30–0.45 mm (0.0118–0.0177
in)
Limit 4. Calculate:
0.80 mm (0.0315 in) • Piston-pin-to-piston-pin-bore clearance
Oil ring Out of specification → Replace the piston pin
End gap (installed) and piston as a set.
0.20–0.70 mm (0.0079–0.0276 • Piston-pin-to-piston-pin-bore clearance =
in) Piston pin bore diameter “b” -
Piston pin outside diameter “a”
EAS24440

CHECKING THE PISTON PIN

1. Check: Piston-pin-to-piston-pin-bore
• Piston pin clearance
Blue discoloration/grooves → Replace the 0.004–0.024 mm (0.0002–0.0009
in)
piston pin, and then check the lubrication sys-
tem.
EAS37P1065
2. Measure: CHECKING THE TIMING CHAIN GUIDE
• Piston pin outside diameter “a” 1. Check:
Out of specification → Replace the piston pin. • Timing chain guide (exhaust side)
Damage/wear → Replace.
Piston pin outside diameter
16.991–17.000 mm (0.6689– EAS24450

0.6693 in) INSTALLING THE PISTON AND CYLINDER

Limit 1. Install:
16.971 mm (0.6681 in) • Top ring “1”
• 2nd ring “2”
• Upper oil ring rail “3”
• Oil ring expander “4”
• Lower oil ring rail “5”
TIP
Be sure to install the piston rings so that the
manufacturer marks or numbers face up.

5-87
 CYLINDER AND PISTON (YP250R)

e 120˚ a

120˚ 120˚

f f
d c b
A
2. Install: a. Top ring
• Piston “1” b. Upper oil ring rail
• Piston pin “2” c. Oil ring expander
• Piston pin clips “3” New d. Lower oil ring rail
TIP e. 2nd ring
f. 20 mm (0.79 in)
• Apply engine oil to the piston pin.
A. Intake side
• Make sure the arrow mark “a” on the piston
points towards the exhaust side of the cylinder. 5. Install:
• Before installing the piston pin clips, cover the • Dowel pins
crankcase opening with a clean rag to prevent • Cylinder gasket New
the clips from falling into the crankcase. • Cylinder
TIP
• While compressing the piston rings with one
hand, install the cylinder with the other hand.
• Pass the timing chain and timing chain guide
(intake side) through the timing chain cavity.

3. Lubricate:
• Piston
• Piston rings
• Cylinder
(with the recommended lubricant)

Recommended lubricant
Engine oil

4. Offset:
• Piston ring end gaps

5-88
 V-BELT AUTOMATIC TRANSMISSION (YP250R)

EAS24610

V-BELT AUTOMATIC TRANSMISSION (YP250R)

Removing the V-belt case cover

7 Nm (0.7 m•kgf, 5.1 ft•Ibf)

T.R
.
6
New 5
4 (11)

10 Nm (1.0 m•kgf, 7.2 ft•Ibf) New

T.R
.

3
New
7 Nm (0.7 m•kgf, 5.1 ft•Ibf) 2
T.R
.

Order Job/Parts to remove Q’ty Remarks

Refer to “GENERAL CHASSIS” on page
Air filter case 4-1.
1 V-belt case air filter cover 1
2 V-belt case air filter element 1
3 V-belt case cover 1
4 V-belt case 1
5 V-belt case gasket 1
6 Dowel pin 2
For installation, reverse the removal proce-
dure.

5-89
 V-BELT AUTOMATIC TRANSMISSION (YP250R)

Removing the V-belt, primary sheave and secondary sheave

22 Nm (2.2 m•kgf, 16 ft•Ibf)

T.R
.
8
7 E
LS

LT
LT

(4) (4)
15 5
* 10
4
11 New 2 3
1
14 12
13 New
LS
New
9
60 Nm (6.0 m•kgf, 43 ft•Ibf)
T.R

LS LS
.

80 Nm (8.0 m•kgf, 58 ft•Ibf)

T.R
.

3 Nm (0.3 m•kgf, 2.2 ft•Ibf)

T.R
.

Order Job/Parts to remove Q’ty Remarks

1 Primary sheave nut/washer 1/1
2 Primary fixed sheave 1
3 Secondary sheave bracket 1
4 Secondary sheave nut 1
5 Spacer 1
6 Clutch housing 1
7 Secondary sheave assembly 1
8 V-belt 1
9 Primary sliding sheave 1
10 Spacer 1
11 Primary sheave cap 1
12 Cam 1
13 Weight 8
14 Slider 4

5-90
 V-BELT AUTOMATIC TRANSMISSION (YP250R)

Removing the V-belt, primary sheave and secondary sheave

22 Nm (2.2 m•kgf, 16 ft•Ibf)

T.R
.
8
7 E
LS

LT
LT

(4) (4)
15 5
* 10
4
11 New 2 3
1
14 12
13 New
LS
New
9
60 Nm (6.0 m•kgf, 43 ft•Ibf)
T.R

LS LS
.

80 Nm (8.0 m•kgf, 58 ft•Ibf)

T.R
.

3 Nm (0.3 m•kgf, 2.2 ft•Ibf)

T.R
.

Order Job/Parts to remove Q’ty Remarks

15 Spacer 4
For installation, reverse the removal proce-
dure.

* Apply Shell BT grease 3® (Yamaha grease G 90793-40016).

Yamaha grease G
90793-40016

5-91
 V-BELT AUTOMATIC TRANSMISSION (YP250R)

Disassembling the secondary sheave

7
6

5 New

12 *
8 1
3 New
4
11 New
9
LS
90 Nm (9.0 m•kgf, 65 ft•Ibf)

T.R
.
11 New

* 10 New

*
LS
*
Order Job/Parts to remove Q’ty Remarks
1 Clutch carrier nut 1
2 Clutch carrier 1
3 Clip 3
4 Clutch carrier plate 1
5 Clutch shoe spring 3
6 Compression spring 1
7 Spring seat 1
8 Guide pin 4
9 Secondary sliding sheave 1
10 O-ring 2
11 Oil seal 2
12 Secondary fixed sheave 1
For assembly, reverse the disassembly pro-
cedure.

* Apply BEL-RAY assembly lube®.

5-92
 V-BELT AUTOMATIC TRANSMISSION (YP250R)

EAS24620

REMOVING THE PRIMARY SHEAVE

1. Remove:
• V-belt case
TIP
Loosen each bolt 1/4 of a turn at a time, in stag-
es and in a crisscross pattern. After all of the
bolts are fully loosened, remove them.
2. Remove:
• Primary sheave nut “1”
• Washer 2. Loosen:
• Primary fixed sheave “2” • Clutch carrier nut “1”
ECA13860

TIP NOTICE
While holding the primary fixed sheave with the Do not remove the clutch carrier nut at this
rotor holding tool “3”, loosen the primary sheave stage.
nut.
TIP
Rotor holding tool While holding the clutch carrier with the sheave
90890-01235 holder “2”, loosen the clutch carrier nut one full
Universal magneto & rotor holder turn with the locknut wrench “3”.
YU-01235
Sheave holder
90890-01701
Primary clutch holder
YS-01880-A
Locknut wrench
90890-01348
YM-01348

2
EAS24630

REMOVING THE SECONDARY SHEAVE

1. Remove:
• Secondary sheave nut “1” 3
• Spacer 1
• Clutch housing “2”
TIP
3. Remove:
While holding the clutch housing with the sheave
• Secondary sheave assembly “1”
holder “3”, loosen the secondary sheave nut.
• V-belt “2”
TIP
Sheave holder
90890-01701 Remove the V-belt and secondary sheave as-
Primary clutch holder sembly from the primary sheave side.
YS-01880-A

5-93
 V-BELT AUTOMATIC TRANSMISSION (YP250R)

EAS24640 EAS24660
DISASSEMBLING THE SECONDARY CHECKING THE CLUTCH SHOES
SHEAVE The following procedure applies to all of the
1. Remove: clutch shoes.
• Clutch carrier nut “1” 1. Check:
TIP • Clutch shoe
While compressing the compression spring with Damage/wear → Replace the clutch shoes
the clutch spring holder “2” and clutch spring and springs as a set.
holder arm “3”, remove the clutch carrier nut. Glazed areas → Sand with coarse sandpa-
per.
Clutch spring holder TIP
90890-01337 After sanding the glazed areas, clean the clutch
Clutch spring holder arm with a cloth.
90890-01464
2. Measure:
• Clutch shoe thickness “a”
Out of specification → Replace the clutch
shoes and springs as a set.

Clutch shoe thickness

3.3 mm (0.13 in)
Wear limit
2.0 mm (0.08 in)

EAS24650

CHECKING THE CLUTCH HOUSING

1. Check:
• Clutch housing
Damage/wear → Replace.
2. Measure:
• Clutch housing inside diameter “a”
Out of specification → Replace the clutch
housing. EAS24670

CHECKING THE V-BELT

Clutch housing inside diameter 1. Check:
145.0 mm (5.71 in) • V-belt “1”
Limit
Cracks/damage/wear → Replace.
145.5 mm (5.73 in)
Grease/oil → Clean the primary and second-
ary sheave.
2. Measure:
• V-belt width “2”
Out of specification → Replace.

5-94
 V-BELT AUTOMATIC TRANSMISSION (YP250R)

EAS24700

V-belt width CHECKING THE PRIMARY SHEAVE

23.0 mm (0.91 in) SLIDERS
Limit 1. Check:
21.0 mm (0.83 in) • Primary sheave slider
Cracks/damage/wear → Replace.
EAS24710

CHECKING THE SECONDARY SHEAVE

1. Check:
• Secondary fixed sheave
• Secondary sliding sheave
Cracks/damage/wear → Replace the sec-
ondary fixed and sliding sheaves as a set.
2. Check:
• Torque cam groove “1”
Damage/wear → Replace the secondary
EAS24680
fixed and sliding sheaves as a set.
CHECKING THE PRIMARY SHEAVE
3. Check:
1. Check:
• Guide pin “2”
• Primary sliding sheave
Damage/wear → Replace the secondary
• Primary fixed sheave
fixed and sliding sheaves as a set.
• Spacer
Cracks/damage/wear → Replace the primary
sliding sheave and primary fixed sheave as a
set.
EAS24690

CHECKING THE PRIMARY SHEAVE

WEIGHTS
The following procedure applies to all of the pri-
mary sheave weights.
1. Check:
• Primary sheave weight 4. Check:
Cracks/damage/wear → Replace. • Spring free length
2. Measure: Out of specification → Replace the spring.
• Primary sheave weight outside diameter
Out of specification → Replace. Compression spring free length
102.4 mm (4.03 in)
Weight outside diameter Limit
20.0 mm (0.79 in) 90.0 mm (3.54 in)
Limit
19.5 mm (0.77 in)

EAS24720

ASSEMBLING THE PRIMARY SHEAVE

1. Clean:
• Primary fixed sheave

5-95
 V-BELT AUTOMATIC TRANSMISSION (YP250R)

• Primary sliding sheave TIP

• Spacer Install the secondary sliding sheave onto the
• Primary sheave weights secondary fixed sheave “2” with the oil seal
• Cam guide “3”.
2. Install:
• Primary sheave weights “1”
Oil seal guide (ø41)
• Spacer “2”
90890-01396
TIP
Before installing the primary sheave weights, lu-
bricate the inside and outside of each weight
with Shell BT grease 3®. 3

Recommended lubricant
Shell BT grease 3® 1
2

3. Install:
• Guide pins “1”
4. Lubricate:
• Guide pin grooves “2”
• O-rings “3” New
(with the recommended lubricant)

EAS24730 Recommended lubricant

ASSEMBLING THE SECONDARY SHEAVE BEL-RAY assembly lube®
1. Lubricate:
• Secondary fixed sheave’s inner surface “1”
• Secondary sliding sheave’s inner surface “2”
• Oil seals
• Bearing
(with the recommended lubricant)

Recommended lubricant
BEL-RAY assembly lube®

5. Install:
• Spring seat
• Compression spring
• Spacer
• Clutch carrier “1”
• Clutch carrier nut “2”
TIP
• While compressing the compression spring
2. Install: with the clutch spring holder “3” and clutch
spring holder arm “4”, install the clutch carrier
• Oil seals New nut.
• Secondary sliding sheave “1” • Install the clutch carrier nut “2” with its tapered
side “a” facing the clutch carrier.

5-96
 V-BELT AUTOMATIC TRANSMISSION (YP250R)

Clutch spring holder Clutch carrier nut

90890-01337 90 Nm (9.0 m·kgf, 65 ft·lbf)

T.
R.
Clutch spring holder arm
90890-01464 TIP
While holding the clutch carrier with the sheave
holder “2”, tighten the clutch carrier nut with the
locknut wrench “3”.

Sheave holder
90890-01701
Primary clutch holder
YS-01880-A
Locknut wrench
90890-01348
YM-01348

2 2

2 3
1
a
EAS24740
3. Install:
INSTALLING THE V-BELT
• Clutch housing “1”
1. Install:
• Spacer
• V-belt “1”
• Secondary sheave nut “2”
• Secondary sheave assembly “2”
ECA37P1011

NOTICE Secondary sheave nut

60 Nm (6.0 m·kgf, 43 ft·lbf)
T.

Do not allow grease to come in contact with

R.

the V-belt or secondary sheave assembly. TIP

TIP While holding the clutch housing with the sheave
• Install the V-belt with the printed arrow mark on holder “3”, tighten the secondary sheave nut.
the V-belt facing in the direction shown in the il-
lustration. Sheave holder
• Install the V-belt onto the primary sheave side. 90890-01701
Primary clutch holder
YS-01880-A

2. Tighten:
• Clutch carrier nut “1”

5-97
 V-BELT AUTOMATIC TRANSMISSION (YP250R)

4. Install: TIP
• V-belt “1” • Make sure that the V-belt case gasket lip fits
• Primary fixed sheave “2” properly around the V-belt case.
• Washer • Tighten the V-belt case bolts in stages and in a
• Primary sheave nut “3” crisscross pattern.
ECA37P1012

NOTICE
Do not allow grease to contact the primary
sheave assembly.
TIP
Install the V-belt in the primary sheave (when the
pulley is at its widest position) and in the second-
ary sheave (when the pulley is at its narrowest
position), and make sure the V-belt is tight.

5. Tighten:
• Primary sheave nut “1”

Primary sheave nut

80 Nm (8.0 m·kgf, 58 ft·lbf)
T.
R.

TIP
While holding the primary fixed sheave with the
rotor holding tool “2”, tighten the primary sheave
nut.

Rotor holding tool

90890-01235
Universal magneto & rotor holder
YU-01235

6. Install:
• V-belt case

5-98
 STARTER CLUTCH AND GENERATOR (YP250R)

EAS24480

STARTER CLUTCH AND GENERATOR (YP250R)

Removing the generator cover and stator coil

7 Nm (0.7 m•kgf, 5.1 ft•Ibf)

T.R
1

.
LT
LT

4
5

7 New
4 LT LS LS

10 Nm (1.0 m•kgf, 7.2 ft•Ibf) 6 2

T.R
.

New

LS
New 3
New

8 Nm (0.8 m•kgf, 5.8 ft•Ibf)

T.R
.

(10)

10 Nm (1.0 m•kgf, 7.2 ft•Ibf)

T.R
.

Order Job/Parts to remove Q’ty Remarks

Drain.
Engine oil Refer to “CHANGING THE ENGINE OIL” on
page 3-27.
Refer to “ENGINE REMOVAL (YP250R)” on
Muffler/Exhaust pipe page 5-61.
Crankshaft position sensor coupler/Stator as-
1 1/1 Disconnect.
sembly coupler
2 Generator cover 1
3 Generator cover gasket 1
4 Dowel pin 2
5 Crankshaft position sensor 1
6 Stator coil 1
7 Oil seal 1
For installation, reverse the removal proce-
dure.

5-99
 STARTER CLUTCH AND GENERATOR (YP250R)

Removing the generator rotor and starter clutch

LT

30 Nm (3.0 m•kgf, 22 ft•Ibf)

T.R
.

80 Nm (8.0 m•kgf, 58 ft•Ibf)

T.R
.

Order Job/Parts to remove Q’ty Remarks

1 Circlip 1
2 Washer 1
3 Starter clutch idle gear shaft 1
4 Starter clutch idle gear 1
5 Generator rotor 1
6 Woodruff key 1
7 Starter clutch gear 1
8 Starter clutch 1
For installation, reverse the removal proce-
dure.

5-100
 STARTER CLUTCH AND GENERATOR (YP250R)

EAS24490

REMOVING THE GENERATOR

1. Remove:
• Generator cover
TIP
Loosen each bolt 1/4 of a turn at a time, in stag-
es and in a crisscross pattern. After all of the
bolts are fully loosened, remove them.
2. Remove:
• Generator rotor nut “1”
• Washer EAS24560

REMOVING THE STARTER CLUTCH

TIP
1. Remove:
• While holding the generator rotor “2” with the • Starter clutch bolts “1”
sheave holder “3”, loosen the generator rotor • Starter clutch
nut.
TIP
• Do not allow the sheave holder to touch the
projection on the generator rotor. • While holding the generator rotor “2” with the
sheave holder “3”, remove the starter clutch
bolts.
Sheave holder • Do not allow the sheave holder to touch the
90890-01701
projection on the generator rotor.
Primary clutch holder
YS-01880-A
Sheave holder
90890-01701
Primary clutch holder
YS-01880-A
1

3
3. Remove:
• Generator rotor “1”
(with the flywheel puller “2”)
• Woodruff key
ECA37P1005 EAS24570

NOTICE CHECKING THE STARTER CLUTCH

To protect the end of the crankshaft, place an 1. Check:
appropriate sized socket between the fly- • Starter clutch rollers “1”
wheel puller set center bolt and the crank- Damage/wear → Replace.
shaft.
TIP
Make sure the flywheel puller is centered over
the generator rotor.

Flywheel puller
90890-01362
Heavy duty puller 1
YU-33270-B

5-101
 STARTER CLUTCH AND GENERATOR (YP250R)

2. Check:
• Starter clutch idle gear Sheave holder
• Starter clutch gear 90890-01701
Burrs/chips/roughness/wear → Replace the Primary clutch holder
YS-01880-A
defective part(s).
3. Check:
• Starter clutch gear’s contact surfaces
Damage/pitting/wear → Replace the starter
clutch gear.
4. Check:
• Starter clutch operation
▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼
a. Install the starter clutch gear “1” onto the
starter clutch “2” and hold the starter clutch.
b. When turning the starter clutch gear clock-
wise “A”, the starter clutch and the starter
clutch gear should engage, otherwise the EAS24500

INSTALLING THE GENERATOR

starter clutch is faulty and must be replaced.
1. Install:
c. When turning the starter clutch gear counter-
• Starter clutch gear
clockwise “B”, it should turn freely, otherwise
• Woodruff key
the starter clutch is faulty and must be re-
• Generator rotor
placed.
• Washer
• Generator rotor nut
TIP
• Clean the tapered portion of the crankshaft and
the generator rotor hub.
• When installing the generator rotor, make sure
the woodruff key is properly seated in the key-
way of the crankshaft.
• Make sure that the blunt-edged corner of the
washer is facing outward.
▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲ 2. Tighten:
EAS24600 • Generator rotor nut “1”
INSTALLING THE STARTER CLUTCH
1. Install: Generator rotor nut
• Starter clutch 80 Nm (8.0 m·kgf, 58 ft·lbf)
T.
R.

• Starter clutch bolts “1”

TIP
Starter clutch bolt • While holding the generator rotor “2” with the
30 Nm (3.0 m·kgf, 22 ft·lbf) sheave holder “3”, tighten the generator rotor
T.
R.

LOCTITE®
nut.
• Do not allow the sheave holder to touch the
TIP
projection on the generator rotor.
• While holding the generator rotor “2” with the
sheave holder “3”, tighten the starter clutch
Sheave holder
bolts.
90890-01701
• Do not allow the sheave holder to touch the Primary clutch holder
projection on the generator rotor. YS-01880-A

5-102
 STARTER CLUTCH AND GENERATOR (YP250R)

TIP
Tighten the generator cover bolts in stages and
1 in a crisscross pattern.

3
3. Apply:
• Sealant
(onto the crankshaft position sensor/stator
assembly lead grommet)

Yamaha bond No. 1215

90890-85505
(Three Bond No.1215®)

4. Install:
• Oil seal “1” New

Installed depth “a”

6.0–7.3 mm (0.24–0.29 in)

1 New

5. Install:
• Generator cover

Generator cover bolt

10 Nm (1.0 m·kgf, 7.2 ft·lbf)
T.
R.

5-103
 ELECTRIC STARTER (YP250R)

EAS24780

ELECTRIC STARTER (YP250R)

Removing the starter motor

7 Nm (0.7 m•kgf, 5.1 ft•Ibf)

T.R
.

2
1

Order Job/Parts to remove Q’ty Remarks

Refer to “GENERAL CHASSIS” on page
Storage box/Air filter case 4-1.
1 Starter motor lead 1 Disconnect.
2 Ground lead 1 Disconnect.
3 Starter motor 1
For installation, reverse the removal proce-
dure.

5-104
 ELECTRIC STARTER (YP250R)

Disassembling the starter motor

7 Nm (0.7 m•kgf, 5.1 ft•Ibf)

T.R
.

11

12 7
13
8
10
9 New 3
4
6
1

New
LS
5 New
New
2 New

New

5 Nm (0.5 m•kgf, 3.6 ft•Ibf)

T.R
.

Order Job/Parts to remove Q’ty Remarks

1 Starter motor front cover 1
2 O-ring 1
3 Shim *
4 Lock washer 1
5 Oil seal 1
6 Bearing 1
7 Starter motor yoke 1
8 Armature assembly 1
9 O-ring 1
10 Shim *
11 Brush holder set 1
12 Starter motor rear cover 1
13 Bushing 1
For assembly, reverse the disassembly pro-
cedure.

5-105
 ELECTRIC STARTER (YP250R)

EAS24790

CHECKING THE STARTER MOTOR Digital circuit tester

1. Check: 90890-03174
• Commutator Model 88 Multimeter with ta-
Dirt → Clean with 600 grit sandpaper. chometer
2. Measure: YU-A1927
• Commutator diameter “a”
Out of specification → Replace the starter
Armature coil
motor.
Commutator resistance “1”
Limit Continuity (0.0100–0.0140 Ω at
22.4 mm (0.88 in) 20 °C (68 °F))
Insulation resistance “2”
No continuity (Above 1 MΩ at 20
°C (68 °F))

3. Measure:
• Mica undercut “a”
Out of specification → Scrape the mica to the b. If any resistance is out of specification, re-
proper measurement with a hacksaw blade place the starter motor.
that has been grounded to fit the commutator.
▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲

Mica undercut (depth) 5. Measure:

1.00 mm (0.04 in) • Brush length “a”
Out of specification → Replace the brushes
TIP as a set.
The mica of the commutator must be undercut to
Limit
ensure proper operation of the commutator.
3.00 mm (0.12 in)

4. Measure:
• Armature assembly resistances (commutator 6. Measure:
and insulation) • Brush spring force
Out of specification → Replace the starter Out of specification → Replace the brush
motor. springs as a set.
▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼
a. Measure the armature assembly resistances Brush spring force
with the digital circuit tester. 7.75 N (790 gf, 27.90 oz)

5-106
 ELECTRIC STARTER (YP250R)

7. Check:
• Gear teeth
Damage/wear → Replace the gear.
8. Check:
• Bearing
Damage/wear → Replace the bearing.
EAS24800

ASSEMBLING THE STARTER MOTOR

1. Install:
• Starter motor rear cover “1”
• Starter motor yoke “2”
• Starter motor front cover “3”
TIP
Align the match marks “a” on the starter motor
yoke with the match marks “b” on the starter mo-
tor front and rear covers.

5-107
 OIL PUMP (YP250R)

EAS24910

OIL PUMP (YP250R)

Removing the oil pump

LS

3 New M

8 E
11
12
13
9
14
2
10 7
6
9 5
4

E
New

7 Nm (0.7 m•kgf, 5.1 ft•Ibf)

T.R
.

12 Nm (1.2 m•kgf, 8.7 ft•Ibf)

T.R
.

Order Job/Parts to remove Q’ty Remarks

Refer to “STARTER CLUTCH AND GENER-
Starter clutch gear ATOR (YP250R)” on page 5-99.
1 Oil baffle plate 1
2 Oil pump assembly 1
3 Oil pump gasket 1
4 Circlip 1
5 Washer 1
6 Oil pump driven gear 1
7 Pin 1
8 Oil pump housing cover 1
9 Pin 2
10 Pin 1
11 Oil pump shaft 1
12 Oil pump inner rotor 1
13 Oil pump outer rotor 1

5-108
 OIL PUMP (YP250R)

Removing the oil pump

LS

3 New M

8 E
11
12
13
9
14
2
10 7
6
9 5
4

E
New

7 Nm (0.7 m•kgf, 5.1 ft•Ibf)

T.R
.

12 Nm (1.2 m•kgf, 8.7 ft•Ibf)

T.R
.

Order Job/Parts to remove Q’ty Remarks

14 Oil pump housing 1
For installation, reverse the removal proce-
dure.

5-109
 OIL PUMP (YP250R)

EAS24960

CHECKING THE OIL PUMP Inner-rotor-to-outer-rotor-tip

1. Check: clearance
• Oil pump drive gear Less than 0.15 mm (0.0059 in)
• Oil pump driven gear Limit
• Oil pump housing 0.23 mm (0.0091 in)
• Oil pump housing cover Outer-rotor-to-oil-pump-housing
Cracks/damage/wear → Replace the defec- clearance
tive part(s). 0.013–0.036 mm (0.0005–0.0014
2. Measure: in)
Limit
• Inner-rotor-to-outer-rotor-tip clearance “a”
0.106 mm (0.0042 in)
• Outer-rotor-to-oil-pump-housing clearance Oil-pump-housing-to-inner-and-
“b” outer-rotor clearance
• Oil-pump-housing-to-inner-rotor-and-outer- 0.04–0.09 mm (0.0016–0.0035 in)
rotor clearance “c” Limit
Out of specification → Replace the oil pump. 0.16 mm (0.0063 in)

3. Check:
• Oil pump operation
Rough movement → Repeat steps (1) and
(2) or replace the defective part(s).

EAS25000

ASSEMBLING THE OIL PUMP

1. Lubricate:
• Inner rotor
• Outer rotor

1. Inner rotor
Recommended lubricant
Engine oil
2. Outer rotor
3. Oil pump housing 2. Lubricate:
• Oil pump shaft
(with the recommended lubricant)

Recommended lubricant
Molybdenum disulfide grease

3. Install:
• Oil pump shaft “1”
• Pin “2”
TIP
When installing the oil pump shaft, align the pin
in the oil pump shaft with the groove “a” in the in-
ner rotor.

5-110
 OIL PUMP (YP250R)

2 a

4. Check:
• Oil pump operation
Refer to “CHECKING THE OIL PUMP” on
page 5-110.
EAS25020

INSTALLING THE OIL PUMP

1. Install:
• Oil pump assembly

Oil pump assembly bolt

7 Nm (0.7 m·kgf, 5.1 ft·lbf)
T.
R.

ECA13890

NOTICE
After tightening the bolts, make sure the oil
pump turns smoothly.

5-111
 TRANSMISSION (YP250R)

EAS26240

TRANSMISSION (YP250R)
Removing the transmission

E
E

A B
LS

New
E

16 Nm (1.6 m•kgf, 11 ft•Ibf)

T.R
.

Order Job/Parts to remove Q’ty Remarks

Rear wheel Refer to “REAR WHEEL” on page 4-15.
Drain.
Final transmission oil Refer to “CHANGING THE FINAL TRANS-
MISSION OIL” on page 3-28.
Refer to “V-BELT AUTOMATIC TRANSMIS-
Secondary sheave assembly SION (YP250R)” on page 5-89.
1 Transmission case cover 1
2 Gasket 1
3 Dowel pin 2
4 Primary drive gear 1
5 Washer 2
6 Washer 1
7 1st wheel gear 1
8 Conical spring washer 1
9 Drive axle 1
10 Main axle 1
11 Conical spring washer 1

5-112
 TRANSMISSION (YP250R)

Removing the transmission

E
E

A B
LS

New
E

16 Nm (1.6 m•kgf, 11 ft•Ibf)

T.R
.

Order Job/Parts to remove Q’ty Remarks

12 Primary driven gear 1
For installation, reverse the removal proce-
dure.

5-113
 TRANSMISSION (YP250R)

EAS26250

REMOVING THE TRANSMISSION

1. Remove:
• Transmission case cover
TIP
Loosen each bolt 1/4 of a turn at a time, in stag-
es and in a crisscross pattern. After all of the
bolts are fully loosened, remove them.

EAS26300

CHECKING THE TRANSMISSION

1. Check:
• Transmission gears
Blue discoloration/pitting/wear → Replace
the defective gear(s).
• Transmission gear dogs
Cracks/damage/rounded edges → Replace
the defective gear(s).
2. Check:
• Transmission gear engagement
(each pinion gear to its respective wheel
gear)
Incorrect → Reassemble the transmission
axle assemblies.
3. Check:
• Transmission gear movement
Rough movement → Replace the defective
part(s).
EAS37P1066

INSTALLING THE TRANSMISSION

1. Install:
• Oil seal “1”
• Oil seal “2”

Oil seal installed depth

0–0.5 mm (0–0.020 in)

a
2

1
a

a. Oil seal installed depth

5-114
 CRANKSHAFT (YP250R)

EAS25960

CRANKSHAFT (YP250R)
Removing the crankshaft

8
9

10
E

22 Nm (2.2 m•kgf, 16 ft•Ibf)

T.R
.
New 1
LS

9
5 12
4
LS
3 E
LS
New New
2
7
32 Nm (3.2 m•kgf, 23 ft•Ibf) 13
T.R
.

6
New
11
LS
10 Nm (1.0 m•kgf, 7.2 ft•Ibf) New
T.R
.

20 Nm (2.0 m•kgf, 14 ft•Ibf)

T.R
.

10 Nm (1.0 m•kgf, 7.2 ft•Ibf)

T.R
.

Order Job/Parts to remove Q’ty Remarks

Refer to “WATER PUMP (YP250R)” on page
Water pump assembly 6-12.
Refer to “ENGINE REMOVAL (YP250R)” on
Engine page 5-61.
Refer to “CYLINDER HEAD (YP250R)” on
Cylinder head page 5-67.
Refer to “CYLINDER AND PISTON
Piston (YP250R)” on page 5-84.
Refer to “V-BELT AUTOMATIC TRANSMIS-
Belt drive SION (YP250R)” on page 5-89.
Refer to “OIL PUMP (YP250R)” on page
Oil pump assembly 5-108.
Refer to “TRANSMISSION (YP250R)” on
Transmission page 5-112.
1 Transmission case breather hose 1
2 Oil strainer cover 1
3 Spring 1
4 Oil strainer 1
5 Breather pipe 1

5-115
 CRANKSHAFT (YP250R)

Removing the crankshaft

8
9

10
E

22 Nm (2.2 m•kgf, 16 ft•Ibf)

T.R
.
New 1
LS

9
5 12
4
LS
3 E
LS
New New
2
7
32 Nm (3.2 m•kgf, 23 ft•Ibf) 13
T.R
.

6
New
11
LS
10 Nm (1.0 m•kgf, 7.2 ft•Ibf) New
T.R
.

20 Nm (2.0 m•kgf, 14 ft•Ibf)

T.R
.

10 Nm (1.0 m•kgf, 7.2 ft•Ibf)

T.R
.

Order Job/Parts to remove Q’ty Remarks

6 Timing chain guide retaining bolt 1
7 Timing chain guide (intake side) 1
8 Right crankcase 1
9 Dowel pin 2
10 Crankshaft assembly 1
11 Timing chain 1
12 Left crankcase 1
13 Oil seal 1
For installation, reverse the removal proce-
dure.

5-116
 CRANKSHAFT (YP250R)

EAS25560

DISASSEMBLING THE CRANKCASE TIP

1. Remove: • Before removing the crankshaft assembly, re-
• Crankcase bolts move the timing chain from the crankshaft
TIP
sprocket.
• The crankshaft assembly cannot be removed if
Loosen each bolt 1/4 of a turn at a time, in stag-
the timing chain is attached onto the crankshaft
es and in a crisscross pattern. After all of the
sprocket.
bolts are fully loosened, remove them.

2. Remove: 2. Remove:
• Right crankcase “1” • Crankshaft assembly “1”
TIP TIP
• Remove the right crankcase with the crank- • Remove the crankshaft assembly with the
case separating tool “2” and M6 bolts “3”. crankcase separating tool “2” and M6 bolts “3”.
• Make sure that the crankcase separating tool • Make sure that the crankcase separating tool
is centered over the crankshaft. is centered over the crankshaft assembly.
ECA37P1013 ECA37P1013

NOTICE NOTICE
• To protect the end of the crankshaft, place • To protect the end of the crankshaft, place
an appropriate sized socket “4” between an appropriate sized socket “4” between
the crankcase separating tool bolt and the the crankcase separating tool bolt and the
crankshaft. crankshaft.
• Do not tap on the crankshaft. • Do not tap on the crankshaft.

Crankcase separating tool Crankcase separating tool

90890-01135 90890-01135
Crankcase separator Crankcase separator
YU-01135-B YU-01135-B

EAS26020

REMOVING THE CRANKSHAFT ASSEMBLY

1. Remove:
• Timing chain “1”

5-117
 CRANKSHAFT (YP250R)

EAS24180

CHECKING THE TIMING CHAIN AND TIMING

CHAIN GUIDE
1. Check:
• Timing chain
Damage/stiffness → Replace the timing
chain and camshaft sprocket as a set.

3. Measure:
• Crankshaft width
Out of specification → Replace the crank-
shaft.

Width A
59.75–59.80 mm (2.352–2.354 in)
2. Check:
• Timing chain guide (intake side)
Damage/wear → Replace.
EAS26060

CHECKING THE CRANKSHAFT AND

CONNECTING ROD
1. Measure:
• Crankshaft runout
Out of specification → Replace the crank-
shaft.
TIP
4. Check:
Turn the crankshaft slowly. • Crankshaft sprocket “1”
Damage/wear → Replace the crankshaft.
Runout limit C • Bearings “2”
0.030 mm (0.0012 in) Cracks/damage/wear → Replace the crank-
shaft.
• Oil pump drive gear “3”
Damage/wear → Replace the crankshaft.

2. Measure:
• Big end side clearance
Out of specification → Replace the crank- 5. Check:
shaft. • Crankshaft journal
Big end side clearance D Scratches/wear → Replace the crankshaft.
0.350–0.850 mm (0.0138–0.0335 • Crankshaft journal oil passage
in) Obstruction → Blow out with compressed air.

5-118
 CRANKSHAFT (YP250R)

1
a

EAS25580 a. Oil seal installed depth

CHECKING THE CRANKCASE
1. Thoroughly wash the crankcase halves in a 3. Install:
mild solvent. • Timing chain “1”
2. Thoroughly clean all the gasket surfaces and TIP
crankcase mating surfaces. Install the timing chain so it is not visible through
3. Check: the opening “a” in the left crankcase “2”.
• Crankcase
Cracks/damage → Replace.
• Oil delivery passages
Obstruction → Blow out with compressed air.
EAS37P1067

CHECKING THE BEARING AND OIL SEAL

1. Check:
• Bearing
Clean and lubricate the bearings, and then
rotate the inner race with your finger.
Rough movement → Replace. 4. Install:
EAS37P1068
• Crankshaft assembly “1”
CHECKING THE OIL STRAINERS (to the left crankcase)
1. Check: TIP
• Oil strainers Install the crankshaft assembly with the crank-
Damage → Replace. shaft installer pot “2”, crankshaft installer bolt “3”,
Contaminants → Clean with solvent. adapter “4”, and spacer “5”.
EAS26210

INSTALLING THE CRANKSHAFT Crankshaft installer pot

1. Lubricate: 90890-01274
• Oil seals Installing pot
• Bearings YU-90058
• Oil pump drive gear Crankshaft installer bolt
90890-01275
Recommended lubricant Bolt
Oil seal YU-90060
Lithium-soap-based grease Adapter (M14)
Bearing, oil pump drive gear 90890-01478
Engine oil Adapter #6
YM-90066
2. Install: Spacer (crankshaft installer)
• Oil seal “1” 90890-04081
(to the left crankcase) Pot spacer
YM-91044
Oil seal installed depth
0–0.5 mm (0–0.020 in)

5-119
 CRANKSHAFT (YP250R)

TIP
5
Install the crankshaft assembly with the crank-
shaft installer pot “2”, crankshaft installer bolt “3”,
adapter “4”, and spacer “5”.

1 Crankshaft installer pot

90890-01274
Installing pot
4 3 YU-90058
2
Crankshaft installer bolt
ECA13970
90890-01275
NOTICE Bolt
To avoid scratching the crankshaft and to YU-90060
ease the installation procedure, lubricate the Adapter (M16)
oil seal lips with lithium-soap-based grease 90890-01280
and each bearing with engine oil. Adapter #7
YM-90067
TIP Spacer
Hold the connecting rod at top dead center 90890-01288
(TDC) with one hand while turning the nut of the
crankshaft installer bolt with the other. Turn the
crankshaft installer bolt until the crankshaft as-
sembly bottoms against the bearing.

EAS25700

ASSEMBLING THE CRANKCASE

1. Thoroughly clean all the gasket mating sur-
faces and crankcase mating surfaces.
2. Apply:
• Sealant
(onto the crankcase mating surfaces) 4. Install:
• Water pump assembly
Yamaha bond No. 1215 • Crankcase bolts
90890-85505
(Three Bond No.1215®) Crankcase bolt
10 Nm (1.0 m·kgf, 7.2 ft·lbf)
T.
R.

TIP
Do not allow any sealant to come into contact TIP
with the oil gallery. Tighten the crankcase bolts in stages and in a
crisscross pattern.
• M6 × 100 mm (3.94 in) bolts: “1”
• M6 × 70 mm (2.76 in) bolts: “2”

3. Install:
• Right crankcase “1”

5-120
 CRANKSHAFT (YP250R)

5-121
 COOLING SYSTEM

RADIATOR (YP125R) ..................................................................................... 6-1

CHECKING THE RADIATOR.................................................................... 6-2
INSTALLING THE RADIATOR.................................................................. 6-2

THERMOSTAT (YP125R) ............................................................................... 6-3

CHECKING THE THERMOSTAT.............................................................. 6-4
INSTALLING THE THERMOSTAT............................................................ 6-4

WATER PUMP (YP125R)................................................................................ 6-5

DISASSEMBLING THE WATER PUMP.................................................... 6-6
CHECKING THE WATER PUMP .............................................................. 6-6
ASSEMBLING THE WATER PUMP.......................................................... 6-6
INSTALLING THE WATER PUMP ............................................................ 6-7

RADIATOR (YP250R) ..................................................................................... 6-8

CHECKING THE RADIATOR.................................................................... 6-9
INSTALLING THE RADIATOR.................................................................. 6-9

THERMOSTAT (YP250R) ............................................................................. 6-10

CHECKING THE THERMOSTAT............................................................ 6-11
INSTALLING THE THERMOSTAT.......................................................... 6-11

WATER PUMP (YP250R).............................................................................. 6-12

DISASSEMBLING THE WATER PUMP.................................................. 6-14
CHECKING THE WATER PUMP ............................................................ 6-14
ASSEMBLING THE WATER PUMP........................................................ 6-14
INSTALLING THE WATER PUMP .......................................................... 6-15
6
 RADIATOR (YP125R)

EAS37P1105

RADIATOR (YP125R)
Removing the radiator

7 Nm (0.7 m•kgf, 5.1 ft•Ibf) 7 Nm (0.7 m•kgf, 5.1 ft•Ibf)

T.R

T.R
.

.
3
1

2
4

(3)
7 Nm (0.7 m•kgf, 5.1 ft•Ibf) 7
T.R
.

(3) 9 5
(3)

8 6

10 Nm (1.0 m•kgf, 7.2 ft•Ibf)

T.R
.

Order Job/Parts to remove Q’ty Remarks

Radiator cover/Radiator air duct/Bottom cov- Refer to “GENERAL CHASSIS” on page
er/Footrest board 4-1.
Drain.
Coolant Refer to “CHANGING THE COOLANT” on
page 3-18.
1 Radiator cap 1
2 Coolant reservoir hose 1
3 Coolant reservoir 1
4 Radiator filler hose 1
5 Radiator inlet hose 1
6 Radiator outlet hose 1
7 Radiator fan motor coupler 1 Disconnect.
8 Radiator 1
9 Radiator fan motor 1
For installation, reverse the removal proce-
dure.

6-1
 RADIATOR (YP125R)

EAS37P1106
Refer to “CHANGING THE COOLANT” on
CHECKING THE RADIATOR
page 3-18.
1. Check:
3. Check:
• Radiator fins
• Cooling system
Obstruction → Clean.
Leaks → Repair or replace any faulty part.
Apply compressed air to the rear of the radia-
tor.
Damage → Repair or replace.
TIP
Straighten any flattened fins with a thin, flat-head
screwdriver.

2. Check:
• Radiator hoses
Cracks/damage → Replace.
3. Check:
• Radiator fan motor
Damage → Replace.
Malfunction → Check and repair.
Refer to “CHECKING THE RADIATOR FAN
MOTOR” on page 8-87.
EAS37P1107

INSTALLING THE RADIATOR

1. Install:
• Radiator outlet hose screw clamp “1”
TIP
Install the radiator outlet hose screw clamp in the
position shown in the illustration.

2. Fill:
• Cooling system
(with the specified amount of the recom-
mended coolant)

6-2
 THERMOSTAT (YP125R)

EAS37P1108

THERMOSTAT (YP125R)
Removing the thermostat

New
10 Nm (1.0 m•kgf, 7.2 ft•Ibf)
T.R
.

2
4
1

Order Job/Parts to remove Q’ty Remarks

Refer to “GENERAL CHASSIS” on page
Storage box 4-1.
Drain.
Coolant Refer to “CHANGING THE COOLANT” on
page 3-18.
1 Radiator inlet hose 1 Disconnect.
2 Thermostat inlet hose 1
3 Thermostat cover 1
4 Thermostat 1
For installation, reverse the removal proce-
dure.

6-3
 THERMOSTAT (YP125R)

EAS37P1109

CHECKING THE THERMOSTAT

1. Check:
• Thermostat
Does not open at 70.5–73.5 °C (158.9–164.3
°F) → Replace. a
▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼
a. Suspend the thermostat “1” in a container “2”
filled with water.
b. Slowly heat the water “3”.
c. Place a thermometer “4” in the water.
d. While stirring the water, observe the thermo- 2. Fill:
stat and thermometer’s indicated tempera- • Cooling system
ture. (with the specified amount of the recom-
mended coolant)
Refer to “CHANGING THE COOLANT” on
page 3-18.
3. Check:
• Cooling system
Leaks → Repair or replace any faulty part.

A. Fully closed
B. Fully open

TIP
If the accuracy of the thermostat is in doubt, re-
place it. A faulty thermostat could cause serious
overheating or overcooling.
▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲
2. Check:
• Thermostat cover
Cracks/damage → Replace.
EAS37P1110

INSTALLING THE THERMOSTAT

1. Install:
• Thermostat
TIP
Install the thermostat with its breather hole “a” in
the position shown in the illustration.

6-4
 WATER PUMP (YP125R)

EAS37P1111

WATER PUMP (YP125R)

Removing the water pump

LT
1

11
7 8 10
9 12

6
10 Nm (1.0 m•kgf, 7.2 ft•Ibf)
T.R
.

4
3

10 Nm (1.0 m•kgf, 7.2 ft•Ibf) 2

T.R
.

10 Nm (1.0 m•kgf, 7.2 ft•Ibf)

T.R
.

Order Job/Parts to remove Q’ty Remarks

Refer to “GENERAL CHASSIS” on page
Storage box/Footrest board 4-1.
1 Thermostat inlet hose 1 Disconnect.
2 Radiator outlet hose 1 Disconnect.
3 Water pump housing cover 1
4 Water pump housing cover gasket 1
5 Cylinder head breather hose 1 Disconnect.
6 Water pump housing 1
7 Water pump housing plate 1 1
8 Water pump housing plate 2 1
9 Water pump housing plate gasket 1
10 Impeller shaft 1
11 Water pump seal 1
12 Bearing 1
For installation, reverse the removal proce-
dure.

6-5
 WATER PUMP (YP125R)

EAS37P1112

DISASSEMBLING THE WATER PUMP TIP

1. Remove: Install the water pump seal with the special tools
• Water pump seal “1” to the specified depth as shown in the illustra-
TIP
tion.
Remove the water pump seal from the inside of
the water pump housing “2”. Installed depth of water pump
seal
0–0.5 mm (0–0.02 in)

Mechanical seal installer

90890-04145
Middle driven shaft bearing driv-
er
2
90890-04058
Bearing driver 40 mm
1 YM-04058

2. Remove:
• Bearing “1” A
TIP 4
Remove the bearing from the outside of the wa- 3
ter pump housing “2”.
1
2

1 A. Push down
3. Mechanical seal installer
2 4. Middle driven shaft bearing driver

EAS37P1113
a
CHECKING THE WATER PUMP
1. Check:
• Water pump housing cover
• Water pump housing
• Impeller shaft
Cracks/damage/wear → Replace.
2. Check:
• Bearing a. Installed depth of water pump seal
Rough movement → Replace.
2. Lubricate:
EAS37P1114
• Water pump seal
ASSEMBLING THE WATER PUMP
1. Install: Recommended lubricant
• Water pump seal “1” New Lithium-soap-based grease
(into the water pump housing “2”)
3. Install:
• Impeller shaft
• Water pump housing plate gasket “1” New
• Water pump housing plate 2 “2”

6-6
 WATER PUMP (YP125R)

• Water pump housing plate 1 “3” Refer to “CHANGING THE COOLANT” on

page 3-18.
Water pump housing plate 1 bolt 3. Check:
10 Nm (1.0 m·kgf, 7.2 ft·lbf) • Cooling system
T.
R.

LOCTITE® Leaks → Repair or replace any faulty part.

TIP
• After installation, check that the impeller shaft
rotates smoothly.
• Be sure to align the bolt holes in the water
pump housing plate gasket and water pump
housing plates. Make sure that the gasket
does not block the holes “a” in the water pump
housing plates.

1 New

3 2

EAS37P1115

INSTALLING THE WATER PUMP

1. Install:
• O-rings New
• Water pump assembly “1”

Water pump assembly bolt

10 Nm (1.0 m·kgf, 7.2 ft·lbf)
T.
R.

TIP
• Lubricate the O-rings with a thin coat of lithium-
soap-based grease.
• Align the projection “a” on the impeller shaft
with the slot “b” in the camshaft sprocket bolt.

a
b

2. Fill:
• Cooling system
(with the specified amount of the recom-
mended coolant)

6-7
 RADIATOR (YP250R)

EAS26380

RADIATOR (YP250R)
Removing the radiator
7 Nm (0.7 m•kgf, 5.1 ft•Ibf) 7 Nm (0.7 m•kgf, 5.1 ft•Ibf)
T.R

T.R
.

.
3
1

2
4

7 Nm (0.7 m•kgf, 5.1 ft•Ibf)

5
(3)
T.R
.

7
(3) 9
(3) 6

10 Nm (1.0 m•kgf, 7.2 ft•Ibf)

T.R
.

Order Job/Parts to remove Q’ty Remarks

Radiator cover/Radiator air duct/Bottom cov- Refer to “GENERAL CHASSIS” on page
er/Footrest board 4-1.
Drain.
Coolant Refer to “CHANGING THE COOLANT” on
page 3-32.
1 Radiator cap 1
2 Coolant reservoir hose 1
3 Coolant reservoir 1
4 Radiator filler hose 1
5 Radiator inlet hose 1
6 Radiator outlet hose 1
7 Radiator fan motor coupler 1 Disconnect.
8 Radiator 1
9 Radiator fan motor 1
For installation, reverse the removal proce-
dure.

6-8
 RADIATOR (YP250R)

EAS26390
Refer to “CHANGING THE COOLANT” on
CHECKING THE RADIATOR
page 3-32.
1. Check:
3. Check:
• Radiator fins
• Cooling system
Obstruction → Clean.
Leaks → Repair or replace any faulty part.
Apply compressed air to the rear of the radia-
tor.
Damage → Repair or replace.
TIP
Straighten any flattened fins with a thin, flat-head
screwdriver.

2. Check:
• Radiator hoses
Cracks/damage → Replace.
3. Check:
• Radiator fan motor
Damage → Replace.
Malfunction → Check and repair.
Refer to “CHECKING THE RADIATOR FAN
MOTOR” on page 8-87.
EAS26400

INSTALLING THE RADIATOR

1. Install:
• Radiator outlet hose screw clamp “1”
TIP
Install the radiator outlet hose screw clamp in the
position shown in the illustration.

2. Fill:
• Cooling system
(with the specified amount of the recom-
mended coolant)

6-9
 THERMOSTAT (YP250R)

EAS26440

THERMOSTAT (YP250R)
Removing the thermostat

3 Nm (0.3 m•kgf, 2.2 ft•Ibf) New

T.R
.
10 Nm (1.0 m•kgf, 7.2 ft•Ibf)
2
T.R
.

Order Job/Parts to remove Q’ty Remarks

Refer to “GENERAL CHASSIS” on page
Storage box 4-1.
Drain.
Coolant Refer to “CHANGING THE COOLANT” on
page 3-32.
1 Radiator inlet hose 1 Disconnect.
2 Thermostat inlet hose 1
3 Thermostat cover 1
4 Thermostat 1
For installation, reverse the removal proce-
dure.

6-10
 THERMOSTAT (YP250R)

EAS26450

CHECKING THE THERMOSTAT

1. Check: a
• Thermostat
Does not open at 80.5–83.5 °C (176.9–182.3
°F) → Replace.
▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼
a. Suspend the thermostat “1” in a container “2”
filled with water.
b. Slowly heat the water “3”.
c. Place a thermometer “4” in the water.
d. While stirring the water, observe the thermo- 2. Fill:
stat and thermometer’s indicated tempera- • Cooling system
ture. (with the specified amount of the recom-
mended coolant)
Refer to “CHANGING THE COOLANT” on
page 3-32.
3. Check:
• Cooling system
Leaks → Repair or replace any faulty part.

A. Fully closed
B. Fully open

TIP
If the accuracy of the thermostat is in doubt, re-
place it. A faulty thermostat could cause serious
overheating or overcooling.
▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲
2. Check:
• Thermostat cover
Cracks/damage → Replace.
EAS26460

INSTALLING THE THERMOSTAT

1. Install:
• Thermostat
TIP
Install the thermostat with its breather hole “a” in
the position shown in the illustration.

6-11
 WATER PUMP (YP250R)

EAS26500

WATER PUMP (YP250R)

Removing the water pump

12 Nm (1.2 m•kgf, 8.7 ft•Ibf)

T.R
.
M

3
2
New LS
LS
9 LT
LS 12 13

8
5

New
10 Nm (1.0 m•kgf, 7.2 ft•Ibf)

T.R
.
7 Nm (0.7 m•kgf, 5.1 ft•Ibf)
New 11
6
T.R
.

LS 7
10
4

New
10 Nm (1.0 m•kgf, 7.2 ft•Ibf)
T.R
.

Order Job/Parts to remove Q’ty Remarks

It is not necessary to remove the water
pump unless the coolant level is extremely
low or the coolant contains engine oil.
Refer to “GENERAL CHASSIS” on page
Bottom cover 4-1.
Refer to “STARTER CLUTCH AND GENER-
Generator rotor ATOR (YP250R)” on page 5-99.
Drain.
Coolant Refer to “CHANGING THE COOLANT” on
page 3-32.
1 Oil baffle plate 1
2 Impeller shaft gear 1
3 Washer 1
4 Radiator outlet hose 1 Disconnect.
5 Water pump outlet pipe 1
6 Water pump housing cover 1
7 Gasket 1
8 Water pump housing 1

6-12
 WATER PUMP (YP250R)

Removing the water pump

12 Nm (1.2 m•kgf, 8.7 ft•Ibf)

T.R
.
M

3
2
New LS
LS
9 LT
LS 12 13

8
5

New
10 Nm (1.0 m•kgf, 7.2 ft•Ibf)

T.R
.
7 Nm (0.7 m•kgf, 5.1 ft•Ibf)
New 11
6
T.R
.

LS 7
10
4

New
10 Nm (1.0 m•kgf, 7.2 ft•Ibf)
T.R
.

Order Job/Parts to remove Q’ty Remarks

9 Circlip 1
10 Impeller shaft 1
11 Water pump seal 1
12 Bearing 1
13 Oil seal 1
For installation, reverse the removal proce-
dure.

A: Oil pump side

6-13
 WATER PUMP (YP250R)

EAS26510 EAS26550

DISASSEMBLING THE WATER PUMP CHECKING THE WATER PUMP

1. Remove: 1. Check:
• Rubber damper holder “1” • Water pump housing cover
• Rubber damper “2” • Water pump housing
(from the impeller, with a thin, flat-head • Impeller shaft
screwdriver) Cracks/damage/wear → Replace.
TIP 2. Check:
Do not scratch the impeller shaft. • Bearing
Rough movement → Replace.
EAS26570

ASSEMBLING THE WATER PUMP

1. Install:
• Oil seal “1” New
(into the water pump housing)
TIP
• Before installing the oil seal, apply tap water or
coolant onto its outer surface.
• Install the oil seal with a socket that matches its
2. Remove: outside diameter.
• Water pump seal “1”
TIP Installed depth of oil seal “a”
Remove the water pump seal from the inside of 8.1–8.7 mm (0.32–0.34 in)
the water pump housing.

1 New

1
2. Install:
3. Remove:
• Bearing “1” • Water pump seal “1” New
• Oil seal “2” TIP
TIP • Install the water pump seal with the special
Remove the bearing and oil seal from the out- tools.
side of the water pump housing. • Before installing the water pump seal, apply
Yamaha bond No.1215 (Three Bond
No.1215®) “2” to the water pump housing “3”.
1

6-14
 WATER PUMP (YP250R)

Mechanical seal installer Impeller shaft tilt limit

90890-04132 0.15 mm (0.0059 in)
Water pump seal installer
YM-33221-A
Middle driven shaft bearing driv-
er
90890-04058
Bearing driver 40 mm
YM-04058
Yamaha bond No. 1215
90890-85505
(Three Bond No.1215®)

1. Straightedge
2. Impeller
5. Install:
• Impeller shaft
• Circlip New
TIP
After installation, check that the impeller shaft ro-
tates smoothly.
A. Push down
4. Mechanical seal installer EAS26580

5. Middle driven shaft bearing driver INSTALLING THE WATER PUMP

1. Install:
3. Install: • Impeller shaft gear “1”
• Rubber damper “1” New TIP
• Rubber damper holder “2” New Align the slot on the impeller shaft with the pro-
TIP jection on the impeller shaft gear when installing.
Before installing the rubber damper, apply tap
water or coolant onto its outer surface.

2. Fill:
• Cooling system
4. Measure: (with the specified amount of the recom-
• Impeller shaft tilt mended coolant)
Out of specification → Repeat steps (3) and Refer to “CHANGING THE COOLANT” on
(4). page 3-32.
ECA14090 3. Check:
NOTICE • Cooling system
Make sure the rubber damper and rubber Leaks → Repair or replace any faulty part.
damper holder are flush with the impeller.

6-15
 FUEL SYSTEM

FUEL TANK..................................................................................................... 7-1

REMOVING THE FUEL TANK .................................................................. 7-3
CHECKING THE FUEL PRESSURE ........................................................ 7-3
INSTALLING THE FUEL TANK................................................................. 7-4

THROTTLE BODY........................................................................................... 7-5

REMOVING THE FUEL HOSE ................................................................. 7-9
CHECKING THE FUEL INJECTOR .......................................................... 7-9
CHECKING THE THROTTLE BODY ........................................................ 7-9
INSTALLING THE INTAKE MANIFOLD (YP125R) ................................... 7-9
INSTALLING THE INTAKE MANIFOLD (YP250R) ................................... 7-9
INSTALLING THE FUEL HOSE .............................................................. 7-10
INSTALLING THE THROTTLE BODY .................................................... 7-10
CHECKING THE THROTTLE POSITION SENSOR ............................... 7-10
CHECKING THE ISC (IDLE SPEED CONTROL) UNIT.......................... 7-10

7
 FUEL TANK

EAS26620

FUEL TANK
Removing the fuel tank
10 Nm (1.0 m•kgf, 7.2 ft•Ibf) 7 Nm (0.7 m•kgf, 5.1 ft•Ibf) 14 Nm (1.4 m•kgf, 10 ft•Ibf)

T.R
T.R

.
T.R

.
.

13 14 Nm (1.4 m•kgf, 10 ft•Ibf)

14

T.R
.
13
12

5
16 10 3

New 8 New
7

6 2

9
17

16

1
15
(4)
4
10 Nm (1.0 m•kgf, 7.2 ft•Ibf) 11
T.R
.

7 Nm (0.7 m•kgf, 5.1 ft•Ibf)

T.R
.

13 Nm (1.3 m•kgf, 9.4 ft•Ibf)

(4) LT
T.R
.

Order Job/Parts to remove Q’ty Remarks

Storage box/Front cowling assembly/Bottom Refer to “GENERAL CHASSIS” on page
cover 4-1.
1 Horn 1
2 Fuel pump coupler 1 Disconnect.
3 Fuel sender coupler 1 Disconnect.
4 Fuel tank breather hose 1
5 Fuel tank overflow hose 1
6 Plastic locking tie 1 YP250R only
7 Tube 1 YP250R only
8 Fuel hose connector cover 1
9 Fuel hose 1 Disconnect.
10 Fuel sender 1
11 Fuel tank bracket 1
12 Radiator fan motor coupler 1 Disconnect.
13 Clamp 3
14 Radiator cap holder bolt 1

7-1
 FUEL TANK

Removing the fuel tank

10 Nm (1.0 m•kgf, 7.2 ft•Ibf) 7 Nm (0.7 m•kgf, 5.1 ft•Ibf) 14 Nm (1.4 m•kgf, 10 ft•Ibf)

T.R
T.R

.
T.R

.
.

13 14 Nm (1.4 m•kgf, 10 ft•Ibf)

14

T.R
.
13
12

5
16 10 3

New 8 New
7

6 2

9
17

16

1
15
(4)
4
10 Nm (1.0 m•kgf, 7.2 ft•Ibf) 11
T.R
.

7 Nm (0.7 m•kgf, 5.1 ft•Ibf)

T.R
.

13 Nm (1.3 m•kgf, 9.4 ft•Ibf)

(4) LT
T.R
.

Order Job/Parts to remove Q’ty Remarks

15 Radiator bracket 1
16 Radiator bolt 2
17 Fuel tank 1
For installation, reverse the removal proce-
dure.

7-2
 FUEL TANK

EAS26630
5. Remove:
REMOVING THE FUEL TANK
• Fuel tank
1. Extract the fuel in the fuel tank through the
fuel tank filler hole with a pump. TIP
2. Remove: To remove the fuel tank, lower the radiator “1”.
• Fuel hose connector cover “1” ECA37P1021

3. Remove: NOTICE
• Fuel hose “2” When removing the fuel tank, be sure not to
ECA37P1023
pull forcefully on the radiator hoses “2”.
NOTICE
• Be sure to disconnect the fuel hose by
hand. Do not forcefully disconnect the
hose with tools. 2
• Although the fuel has been removed from
the fuel tank, be careful when removing the
fuel hose, since there may be fuel remain- 2
ing in it. 1
• Do not disconnect the fuel hose from the 2
fuel hose connector. Disconnect the con-
nector from the fuel pump.
EAS37P1071
TIP
CHECKING THE FUEL PRESSURE
Before removing the hose, place a few rags in 1. Check:
the area under where it will be removed. • Pressure regulator operation
▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼
a. Remove the fuel hose connector cover “1”,
and then remove the fuel hose “2” from the
fuel pump.
ECA37P1024

NOTICE
Although the fuel has been removed from
1 2 the fuel tank, be careful when removing the
fuel hose, since there may be fuel remaining
in it.
TIP
4. Remove:
• Fuel sender “1” Before removing the hose, place a few rags in
the area under where it will be removed.
TIP
Remove the fuel sender with the fuel sender
wrench “2”.

Fuel sender wrench

90890-11098

1 2
2

b. Connect the pressure gauge “3” and fuel

pressure adapter “4”.

7-3
 FUEL TANK

2. Install:
Pressure gauge • Fuel hose
90890-03153 • Fuel hose connector cover
YU-03153 ECA37P1022

Fuel pressure adapter NOTICE

90890-03181
When installing the fuel hose, make sure that
it is securely connected, and that the fuel
hose connector cover is in the correct posi-
tion, otherwise the fuel hose will not be prop-
3 erly installed.
2
TIP
• Wipe up any fuel remaining in the recess “a” in
the fuel pump with a dry rag “1”.
4
• After installing the fuel hose connector cover
“2”, make sure that it is installed securely.

c. Start the engine. 1

d. Measure the fuel pressure.

Output pressure
250.0 kPa (2.50 kgf/cm², 36.3
psi)
a
Faulty → Replace the fuel tank (with fuel
pump).
e. Connect the fuel hose and install the fuel
hose connector cover.
Refer to “INSTALLING THE FUEL TANK” on
page 7-4.
▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲ 2
EAS37P1072

INSTALLING THE FUEL TANK

1. Install:
• Gasket New
• Fuel sender “1”
TIP
Install the fuel sender with the fuel sender
wrench “2”.

Fuel sender wrench

90890-11098

7-4
 THROTTLE BODY

EAS26970

THROTTLE BODY
Removing the throttle body (YP125R)
10 Nm (1.0 m•kgf, 7.2 ft•Ibf) 10 Nm (1.0 m•kgf, 7.2 ft•Ibf) 1.5 Nm (0.15 m•kgf, 1.1 ft•Ibf)
T.R

T.R

T.R
.

.
10 Nm (1.0 m•kgf, 7.2 ft•Ibf) 2 Nm (0.2 m•kgf, 1.4 ft•Ibf)
T.R

T.R
.

.
12 Nm (1.2 m•kgf, 8.7 ft•Ibf) 12
9

T.R
.
4 5
11
2
E
3 7
15
1
13 14 10
New
6
New
8
16 LS

New

10 Nm (1.0 m•kgf, 7.2 ft•Ibf) LS

T.R
.

5 Nm (0.5 m•kgf, 3.6 ft•Ibf)

T.R
.

3 Nm (0.3 m•kgf, 2.2 ft•Ibf)

T.R
.

Order Job/Parts to remove Q’ty Remarks

Refer to “GENERAL CHASSIS” on page
Storage box/Footrest board 4-1.
1 Intake air pressure sensor hose 1
2 Intake air pressure sensor coupler 1 Disconnect.
3 Intake air pressure sensor 1
4 Intake air pressure sensor bracket 1
5 ISC (idle speed control) unit coupler 1 Disconnect.
6 Throttle position sensor coupler 1 Disconnect.
7 Throttle position sensor 1
8 Throttle cable 2 Disconnect.
9 Air filter case joint clamp screw 1 Loosen.
10 Throttle body joint clamp screw 1 Loosen.
11 Throttle body 1
12 Fuel injector coupler 1 Disconnect.
13 Fuel hose connector cover 1
14 Fuel injector assembly 1

7-5
 THROTTLE BODY

Removing the throttle body (YP125R)

10 Nm (1.0 m•kgf, 7.2 ft•Ibf) 10 Nm (1.0 m•kgf, 7.2 ft•Ibf) 1.5 Nm (0.15 m•kgf, 1.1 ft•Ibf)
T.R

T.R

T.R
.

.
10 Nm (1.0 m•kgf, 7.2 ft•Ibf) 2 Nm (0.2 m•kgf, 1.4 ft•Ibf)

T.R

T.R
.

.
12 Nm (1.2 m•kgf, 8.7 ft•Ibf) 12
9

T.R
.
4 5
11
2
E
3 7
15
1
13 14 10
New
6
New
8
16 LS

New

10 Nm (1.0 m•kgf, 7.2 ft•Ibf) LS

T.R
.

5 Nm (0.5 m•kgf, 3.6 ft•Ibf)

T.R
.
T.R
.
3 Nm (0.3 m•kgf, 2.2 ft•Ibf)

Order Job/Parts to remove Q’ty Remarks

15 Intake manifold 1
16 Intake manifold joint 1
For installation, reverse the removal proce-
dure.

7-6
 THROTTLE BODY

Removing the throttle body (YP250R)

10 Nm (1.0 m•kgf, 7.2 ft•Ibf) 2 Nm (0.2 m•kgf, 1.4 ft•Ibf)
T.R

T.R
.

.
2
3 12
6
4 7
5 10

10 Nm (1.0 m•kgf, 7.2 ft•Ibf)

T.R
.

13 9
3 Nm (0.3 m•kgf, 2.2 ft•Ibf)
T.R
.

12 Nm (1.2 m•kgf, 8.7 ft•Ibf)

T.R
.

11
15
1 New
8
16
LS
E 8
New
14 LS 17

New

5 Nm (0.5 m•kgf, 3.6 ft•Ibf)

T.R
.

10 Nm (1.0 m•kgf, 7.2 ft•Ibf)

T.R
.

Order Job/Parts to remove Q’ty Remarks

Refer to “GENERAL CHASSIS” on page
Storage box/Footrest board 4-1.
1 Intake air pressure sensor hose 1
2 Intake air pressure sensor coupler 1 Disconnect.
3 Intake air pressure sensor 1
4 Intake air pressure sensor bracket 1
5 ISC (idle speed control) unit coupler 1 Disconnect.
6 Throttle position sensor coupler 1 Disconnect.
7 Throttle position sensor 1
8 Throttle cable 2 Disconnect.
9 Breather hose (air filter case to throttle body) 1
10 Air filter case joint clamp screw 1 Loosen.
11 Throttle body joint clamp screw 1 Loosen.
12 Throttle body 1
13 Fuel injector coupler 1 Disconnect.
14 Fuel hose connector cover 1
15 Fuel injector assembly 1
16 Intake manifold 1

7-7
 THROTTLE BODY

Removing the throttle body (YP250R)

10 Nm (1.0 m•kgf, 7.2 ft•Ibf) 2 Nm (0.2 m•kgf, 1.4 ft•Ibf)
T.R

T.R
.

.
2
3 12
6
4 7
5 10

10 Nm (1.0 m•kgf, 7.2 ft•Ibf)

T.R
.

13 9
3 Nm (0.3 m•kgf, 2.2 ft•Ibf)
T.R
.

12 Nm (1.2 m•kgf, 8.7 ft•Ibf)

T.R
.

11
15
1 New
8
16
LS
E 8
New
14 LS 17

New

5 Nm (0.5 m•kgf, 3.6 ft•Ibf)

T.R
.

10 Nm (1.0 m•kgf, 7.2 ft•Ibf)

T.R
.

Order Job/Parts to remove Q’ty Remarks

17 Intake manifold joint 1
For installation, reverse the removal proce-
dure.

7-8
 THROTTLE BODY

EAS37P1074
b. Blow out all of the passages with compressed
REMOVING THE FUEL HOSE
air.
1. Extract the fuel in the fuel tank through the
▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲
fuel tank filler hole with a pump.
2. Remove: 3. Check: (YP250R only)
• Fuel hose connector cover “1” • Piston valve
3. Disconnect: Damage/scratches/wear → Replace.
• Fuel hose “2” • Piston valve diaphragm
ECA37P1025 Cracks/tears → Replace.
NOTICE 4. Check: (YP250R only)
• Be sure to disconnect the fuel hose by • Vacuum chamber cover
hand. Do not forcefully disconnect the • Piston valve spring
hose with tools. Cracks/damage → Replace.
• Although the fuel has been removed from 5. Check: (YP250R only)
the fuel tank, be careful when removing the • Piston valve movement
fuel hose, since there may be fuel remain- Insert the piston valve into the throttle body
ing in it. and move it up and down.
• Do not disconnect the fuel hose from the Tightness → Replace the piston valve.
fuel hose connector. Disconnect the con-
nector from the fuel pump.
TIP
Before removing the hose, place a few rags in
the area under where it will be removed.

EAS37P1116

INSTALLING THE INTAKE MANIFOLD

(YP125R)
1 2 1. Install:
• Intake manifold joint “1”
• Intake manifold “2”
EAS26980
TIP
CHECKING THE FUEL INJECTOR Make sure that the projection “a” on the intake
1. Check: manifold joint is facing down.
• Fuel injector
Damage → Replace.
EAS26990

CHECKING THE THROTTLE BODY

1. Check: 2
• Throttle body
Cracks/damage → Replace the throttle body. 1
2. Check:
• Fuel passages a
Obstructions → Clean.
▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼ EAS37P1073
a. Wash the throttle body in a petroleum-based INSTALLING THE INTAKE MANIFOLD
solvent. (YP250R)
Do not use any caustic carburetor cleaning 1. Install:
solution. • Intake manifold joint “1”

7-9
 THROTTLE BODY

EAS37P1076
TIP INSTALLING THE THROTTLE BODY
Make sure that the recess “a” in the intake man- 1. Install:
ifold joint is aligned with the thermostat cover. • Throttle body
TIP
Align the projection “a” on the throttle body with
the slot “b” in the throttle body joint.
1
A

a
a

EAS37P1075 b
INSTALLING THE FUEL HOSE
1. Install:
• Fuel hose B
• Fuel hose connector cover
ECA37P1026

NOTICE b
a
When installing the fuel hose, make sure that
it is securely connected, and that the fuel
hose connector cover is in the correct posi-
tion, otherwise the fuel hose will not be prop-
erly installed.
TIP
A. YP125R
• Wipe up any fuel remaining in the recess “a” in
B. YP250R
the fuel pump with a dry rag “1”.
• After installing the fuel hose connector cover EAS37P1077

“2”, make sure that it is installed securely. CHECKING THE THROTTLE POSITION
SENSOR
1 1. Check:
• Throttle position sensor
Refer to “CHECKING THE THROTTLE PO-
SITION SENSOR” on page 8-88.
EAS37P1078

a CHECKING THE ISC (IDLE SPEED

CONTROL) UNIT
1. Check:
• ISC (idle speed control) unit
Refer to “CHECKING THE ISC (IDLE
SPEED CONTROL) UNIT” on page 8-90.

7-10
 THROTTLE BODY

7-11
 ELECTRICAL SYSTEM

IGNITION SYSTEM ......................................................................................... 8-1

CIRCUIT DIAGRAM .................................................................................. 8-1
TROUBLESHOOTING .............................................................................. 8-3

ELECTRIC STARTING SYSTEM .................................................................... 8-5

CIRCUIT DIAGRAM .................................................................................. 8-5
STARTING CIRCUIT CUT-OFF SYSTEM OPERATION .......................... 8-7
TROUBLESHOOTING .............................................................................. 8-9

CHARGING SYSTEM.................................................................................... 8-11

CIRCUIT DIAGRAM ................................................................................ 8-11
TROUBLESHOOTING ............................................................................ 8-13

LIGHTING SYSTEM ...................................................................................... 8-15

CIRCUIT DIAGRAM ................................................................................ 8-15
TROUBLESHOOTING ............................................................................ 8-17

SIGNALING SYSTEM ................................................................................... 8-19

CIRCUIT DIAGRAM ................................................................................ 8-19
TROUBLESHOOTING ............................................................................ 8-21

COOLING SYSTEM....................................................................................... 8-27

CIRCUIT DIAGRAM ................................................................................ 8-27
TROUBLESHOOTING ............................................................................ 8-29

FUEL INJECTION SYSTEM.......................................................................... 8-31

CIRCUIT DIAGRAM ................................................................................ 8-31
ECU SELF-DIAGNOSTIC FUNCTION.................................................... 8-33
TROUBLESHOOTING METHOD............................................................ 8-34
DIAGNOSTIC MODE .............................................................................. 8-34
TROUBLESHOOTING DETAILS ............................................................ 8-36
DIAGNOSTIC CODE TABLE .................................................................. 8-54

FUEL PUMP SYSTEM................................................................................... 8-57

CIRCUIT DIAGRAM ................................................................................ 8-57
TROUBLESHOOTING ............................................................................ 8-59

IMMOBILIZER SYSTEM................................................................................ 8-61

8
CIRCUIT DIAGRAM ................................................................................ 8-61
GENERAL INFORMATION ..................................................................... 8-63
PART REPLACEMENT AND KEY CODE REGISTRATION
REQUIREMENTS................................................................................... 8-63
TROUBLESHOOTING ............................................................................ 8-67
SELF-DIAGNOSIS FAULT CODE INDICATION..................................... 8-67
ELECTRICAL COMPONENTS...................................................................... 8-71
CHECKING THE SWITCHES ................................................................. 8-73
CHECKING THE BULBS AND BULB SOCKETS ................................... 8-76
CHECKING THE FUSES ........................................................................ 8-77
CHECKING AND CHARGING THE BATTERY....................................... 8-78
CHECKING THE RELAYS ...................................................................... 8-80
CHECKING THE TURN SIGNAL/HAZARD RELAY................................ 8-81
CHECKING THE SPARK PLUG CAP ..................................................... 8-82
CHECKING THE IGNITION COIL ........................................................... 8-82
CHECKING THE IGNITION SPARK GAP............................................... 8-83
CHECKING THE CRANKSHAFT POSITION SENSOR.......................... 8-83
CHECKING THE LEAN ANGLE SENSOR.............................................. 8-84
CHECKING THE STARTER MOTOR OPERATION ............................... 8-84
CHECKING THE STATOR COIL ............................................................ 8-85
CHECKING THE RECTIFIER/REGULATOR .......................................... 8-85
CHECKING THE HORN.......................................................................... 8-85
CHECKING THE FUEL SENDER ........................................................... 8-86
CHECKING THE FUEL LEVEL WARNING LIGHT ................................. 8-86
CHECKING THE SPEED SENSOR ........................................................ 8-87
CHECKING THE RADIATOR FAN MOTOR ........................................... 8-87
CHECKING THE COOLANT TEMPERATURE SENSOR....................... 8-87
CHECKING THE THROTTLE POSITION SENSOR ............................... 8-88
CHECKING THE INTAKE AIR PRESSURE SENSOR ........................... 8-88
CHECKING THE INTAKE AIR TEMPERATURE SENSOR .................... 8-89
CHECKING THE AIR TEMPERATURE SENSOR .................................. 8-89
CHECKING THE ISC (IDLE SPEED CONTROL) UNIT.......................... 8-90
CHECKING THE V-BELT REPLACEMENT INDICATOR RESET
COUPLER .............................................................................................. 8-90
 EAS27100
EAS27090

W/R
Gy/B P/W Y/G Br/W L B/W W/R L/Y L/W L/R Sb B/R G B1 W/B
Gy/B W/R R W
2 G/R Y Gy/G Gy/R Gy/B Y/L R/G Gy R/B Lg G/B P B2 O/B O

L/R R/B L/Y G/Y Gy/B

R/B W/Y
W W R L/Y L/R
W W2 W W G/Y R/B (BLUE)
W2 W2 3 G/R Gy/B
W3 W
1 W3 W3 B B
W/R
18 25 32
19 Gy/B R/B
B
B R 17 Gy/R Gy/B Y G/R G/R O O
B R/B L/R 20
W W2 W3 R R A
R (BLACK)
(BLUE) 33 A
CIRCUIT DIAGRAM

R Gy/R Gy/R A Gy/R Gy/R

B
B L/W L/Y
W/Y L/Y 26 Y Y A Y Y L
(BLACK) B Gy/B Gy/R Gy/R Gy/B
Gy/B Gy/B A Gy/B Y
13 (BLUE) Y
12 L/W
L/Y
34
IGNITION SYSTEM

14 O/B R/B R/L O/B WIRE HARNESS SUB-WIRE HARNESS

4 B
L/W
R/L R 21 L/W W/Y Gy/R (BLACK) (BLACK)
B L/W
B Gy/B P/W Gy/R 27 P/W P/W O/B O/B R/B
B Gy/B
R (BLACK)
B B B
22 23 24
16
Gy/B
R 35
Br/W Gy/B L/W 31 Gy/G Gy/G Gy/B
B
28
5 15 (GREEN)
ON Br/W Br/W B/R B/R R/B
Dg Br/W Ch
Br/R Br/R
OFF L/W W/Y G/Y Br B1 B2 R/B B/R
OPEN W L Gy/G Gy/B
Gy/R
R R LOCK Dg Br/W Ch Br G/Y
Ch Br/W Dg Y/G Y/G (BLACK)
Br/L Br/L P Gy/R Y/G Gy/B 29 Gy/B
G/Y Br W/Y L/W

6 B1 P P
Lg Sb
Br/L Br/R R R/G R/G Lg Lg
36 P G
G G
7 Sb Sb (BLACK)
Gy/R
R R/W Gy Gy/B Gy/R O/R B/W P Gy
30 Gy/B Gy
8
Br/R Br/R2
G/B
9 W/B
B/W R/L Br/L R/B R/B
Y/L G/L R/B Y/L
10
R/G B2 B Br/L R/Y
R/W Lg Y/L
11 B2 B/W
Br/L Br

8-1
R/B
B/W Br/R2
R/Y R/Y2
76 Y/L
Br/W Br
40 R/Y
R/L R/W Br/R2 38
L/B 39
R/B P
R/Y2 W/B (BLACK)

74 L/B W/B
R/W Br/W
G/L Br
L R Br
R/B G/B
41 L/B R/Y Br/W P 37
B
G B
L G/B
B/W R/L
42 43 44 45 46
L
Y/L Y/L

Y/L B B
L Y G P B G/Y
B/W 75 Y/L R 73
R/L Dg Br/W Ch L/B R/Y Br
(BLACK) (BLACK)
G Y Dg Ch B G/Y Br
G Y G/Y B P
B
Ch Br/W Dg Br R/Y L/B

R/B
60 G/L R/L Y/L Br Y Dg Ch

Br
Sb
Gy
61 62 57 B Sb Br B

54 Ch B Ch Dg Dg B 50 Ch Br G/Y 47 Dg Br G/Y
G Y Br

63 64 65 66 67 68 69 70 71 53 52 51 49 48 49
B 55 55 56 56

Sb Ch Br
B/L B G Br Br W
B B
B/L Gy B G/Y
Ch Dg Y R/B R/L Sb Y B G/Y B
G/L Br Y/L B/L Gy B 58 (BLACK)
59 Sb B B Br G B Dg Br B
72 Br Ch
B Gy B B B Y B G/Y
G/Y B
B2 B1 (BLACK)
B B
B1 B1 B/L
IGNITION SYSTEM
 IGNITION SYSTEM

2. Crankshaft position sensor

5. Main switch
6. ECU fuse
9. Ignition fuse
12.Battery
13.Main fuse
17.Frame ground
18.Sidestand switch
29.Lean angle sensor
31.ECU (engine control unit)
32.Ignition coil
33.Spark plug

8-2
 IGNITION SYSTEM

EAS27120

TROUBLESHOOTING
The ignition system fails to operate (no spark or intermittent spark).
TIP
• Before troubleshooting, remove the following part(s):
1. Storage box
2. Front cowling
3. Storage compartment
4. Footrest board

1. Check the fuses. NG →

(Main, ECU, and ignition)
Replace the fuse(s).
Refer to “CHECKING THE FUS-
ES” on page 8-77.

OK ↓
2. Check the battery. NG →
Refer to “CHECKING AND • Clean the battery terminals.
CHARGING THE BATTERY” on • Recharge or replace the battery.
page 8-78.
OK ↓
3. Check the spark plug. NG →
Refer to “CHECKING THE SPARK Re-gap or replace the spark plug.
PLUG” on page 3-24.

OK ↓
4. Check the ignition spark gap. OK →
Refer to “CHECKING THE IGNI- Ignition system is OK.
TION SPARK GAP” on page 8-83.

NG ↓
5. Check the spark plug cap. NG →
Refer to “CHECKING THE SPARK Replace the spark plug cap.
PLUG CAP” on page 8-82.
OK ↓
6. Check the ignition coil. NG →
Refer to “CHECKING THE IGNI- Replace the ignition coil.
TION COIL” on page 8-82.

OK ↓
7. Check the crankshaft position sen- NG →
sor.
Replace the crankshaft position sen-
Refer to “CHECKING THE CRANK-
sor/stator assembly.
SHAFT POSITION SENSOR” on
page 8-83.

OK ↓

8-3
 IGNITION SYSTEM

8. Check the main switch. NG →

Refer to “CHECKING THE Replace the main switch/immobilizer unit.
SWITCHES” on page 8-73.
OK ↓
9. Check the sidestand switch. NG →
Refer to “CHECKING THE Replace the sidestand switch.
SWITCHES” on page 8-73.
OK ↓
10.Check the lean angle sensor. NG →
Refer to “CHECKING THE LEAN Replace the lean angle sensor.
ANGLE SENSOR” on page 8-84.

OK ↓
11.Check the entire ignition system NG →
wiring. Properly connect or repair the ignition sys-
Refer to “CIRCUIT DIAGRAM” on tem wiring.
page 8-1.

OK ↓
Replace the ECU.

8-4
 EAS27170
EAS27160

W/R
Gy/B P/W Y/G Br/W L B/W W/R L/Y L/W L/R Sb B/R G B1 W/B
Gy/B W/R R W
2 G/R Y Gy/G Gy/R Gy/B Y/L R/G Gy R/B Lg G/B P B2 O/B O

L/R R/B L/Y G/Y Gy/B

R/B W/Y
W W R L/Y L/R
W W2 W W G/Y R/B (BLUE)
W2 W2 3 G/R Gy/B
W3 W
1 W3 W3 B B
W/R
18 25 32
19 Gy/B R/B
B
B R 17 Gy/R Gy/B Y G/R G/R O O
B R/B L/R 20
W W2 W3 R R A
R (BLACK)
(BLUE) 33 A
R Gy/R Gy/R A Gy/R Gy/R
CIRCUIT DIAGRAM

B
B L/W L/Y
W/Y L/Y 26 Y Y A Y Y L
(BLACK) B Gy/B Gy/R Gy/R Gy/B
Gy/B Gy/B A Gy/B Y
13 (BLUE) Y
12 L/W
L/Y
34
14 O/B R/B R/L O/B WIRE HARNESS SUB-WIRE HARNESS
4 B
L/W
R/L R 21 L/W W/Y Gy/R (BLACK) (BLACK)
B L/W
B Gy/B P/W Gy/R 27 P/W P/W O/B O/B R/B
B Gy/B
R (BLACK)
B B B
22 23 24
16
Gy/B
R 35
Br/W Gy/B L/W 31 Gy/G Gy/G Gy/B
B
28
5 15 (GREEN)
ON Br/W Br/W B/R B/R R/B
Dg Br/W Ch
Br/R Br/R
OFF L/W W/Y G/Y Br B1 B2 R/B B/R
OPEN W L Gy/G Gy/B
Gy/R
R R LOCK Dg Br/W Ch Br G/Y
Ch Br/W Dg Y/G Y/G (BLACK)
Br/L Br/L P Gy/R Y/G Gy/B 29 Gy/B
G/Y Br W/Y L/W

6 B1 P P
Lg Sb
Br/LBr/R R R/G R/G Lg Lg
36 P G
G G
7 Sb Sb (BLACK)
Gy/R
R R/W Gy Gy/B Gy/R O/R B/W P Gy
30 Gy/B Gy
ELECTRIC STARTING SYSTEM

8
Br/R Br/R2
G/B
9 W/B
B/W R/L Br/L R/B R/B
Y/L G/L R/B Y/L
10
R/G B2 B Br/L R/Y
R/W Lg Y/L
11 B2 B/W
Br/L Br

R/B

8-5
B/W Br/R2
R/Y R/Y2
76 Y/L
Br/W Br
40 R/Y
R/L R/W Br/R2 38
L/B 39
R/B P
R/Y2 W/B (BLACK)

74 L/B W/B
R/W Br/W
G/L Br
L R Br
R/B G/B
41 L/B R/Y Br/W P 37
B
G B
L G/B
B/W R/L
42 43 44 45 46
L
Y/L Y/L

Y/L B B
L Y G P B G/Y
B/W 75 Y/L R 73
R/L Dg Br/W Ch L/B R/Y Br
(BLACK) (BLACK)
G Y Dg Ch B G/Y Br
G Y G/Y B P
B
Ch Br/W Dg Br R/Y L/B

R/B
60 G/L R/L Y/L Br Y Dg Ch

Br
Sb
Gy
61 62 57 B Sb Br B

54 Ch B Ch Dg Dg B 50 Ch Br G/Y 47 Dg Br G/Y
G Y Br

63 64 65 66 67 68 69 70 71 53 52 51 49 48 49
B 55 55 56 56

Sb Ch Br
B/L B G Br Br W
B B
B/L Gy B G/Y
Ch Dg Y R/B R/L Sb Y B G/Y B
G/L Br Y/L B/L Gy B 58 (BLACK)
59 Sb B B Br G B Dg Br B
72 Br Ch
B Gy B B B Y B G/Y
G/Y B
B2 B1 (BLACK)
B B
B1 B1 B/L
ELECTRIC STARTING SYSTEM
 ELECTRIC STARTING SYSTEM

5. Main switch
9. Ignition fuse
11.Signaling system fuse
12.Battery
13.Main fuse
14.Starter relay
15.Starter motor
16.Diode
17.Frame ground
18.Sidestand switch
20.Starting circuit cut-off relay
22.Start switch
24.Front brake light switch
46.Rear brake light switch

8-6
 ELECTRIC STARTING SYSTEM

EAS27180

STARTING CIRCUIT CUT-OFF SYSTEM OPERATION

If the main switch is set to “ON” (switch circuit is closed), the starter motor can only operate if the fol-
lowing conditions are met:
• The brake lever is pulled to the handlebar (the brake switch is closed) and the sidestand is up (the
sidestand switch is closed).
The starting circuit cut-off relay prevents the starter motor from operating when neither of these condi-
tions has been met. In this instance, the starting circuit cut-off relay is open so current cannot reach the
starter motor. When at least one of the above conditions has been met, the starting circuit cut-off relay
is closed and the engine can be started by pressing the start switch “ ”.

13

12
11
1

10

2 4
5
3

7 8 9

8-7
 ELECTRIC STARTING SYSTEM

1. Battery
2. Main fuse
3. Main switch
4. Ignition fuse
5. Starting circuit cut-off relay
6. Sidestand switch
7. Signaling system fuse
8. Front brake light switch
9. Rear brake light switch
10. Start switch
11. Diode
12. Starter relay
13. Starter motor

8-8
 ELECTRIC STARTING SYSTEM

EAS27190

TROUBLESHOOTING
The starter motor fails to turn.
TIP
• Before troubleshooting, remove the following part(s):
1. Storage box
2. Front cowling
3. Storage compartment

1. Check the fuses. NG →

(Main, ignition, and signaling sys-
tem) Replace the fuse(s).
Refer to “CHECKING THE FUS-
ES” on page 8-77.

OK ↓
2. Check the battery. NG →
Refer to “CHECKING AND • Clean the battery terminals.
CHARGING THE BATTERY” on • Recharge or replace the battery.
page 8-78.

OK ↓
3. Check the starter motor operation. OK →
Starter motor is OK. Perform the electric
Refer to “CHECKING THE START-
starting system troubleshooting, starting
ER MOTOR OPERATION” on page
with step 5.
8-84.

NG ↓
4. Check the starter motor. NG →
Refer to “CHECKING THE START-
ER MOTOR” on page 5-46 and Repair or replace the starter motor.
“CHECKING THE STARTER MO-
TOR” on page 5-106.

OK ↓
5. Check the starting circuit cut-off re- NG →
lay.
Replace the starting circuit cut-off relay.
Refer to “CHECKING THE RE-
LAYS” on page 8-80.

OK ↓
6. Check the starter relay. NG →
Refer to “CHECKING THE RE- Replace the starter relay.
LAYS” on page 8-80.
OK ↓
7. Check the main switch. NG →
Refer to “CHECKING THE Replace the main switch/immobilizer unit.
SWITCHES” on page 8-73.

OK ↓

8-9
 ELECTRIC STARTING SYSTEM

8. Check the sidestand switch. NG →

Refer to “CHECKING THE Replace the sidestand switch.
SWITCHES” on page 8-73.
OK ↓
9. Check the brake light switches NG →
(front and rear).
Replace the brake light switch(es).
Refer to “CHECKING THE
SWITCHES” on page 8-73.
OK ↓
10.Check the start switch. NG →
The start switch is faulty. Replace the right
Refer to “CHECKING THE
handlebar switch.
SWITCHES” on page 8-73.

OK ↓
11.Check the entire starting system NG →
wiring. Properly connect or repair the starting sys-
Refer to “CIRCUIT DIAGRAM” on tem wiring.
page 8-5.

OK ↓
The starting system circuit is OK.

8-10
 EAS27210
EAS27200

W/R
Gy/B
Gy/B W/R R W
2
L/R R/B
CIRCUIT DIAGRAM

W W R L/Y
W W2 W W
1 W2 W2 3
W3 W W3 W3 B B 18
CHARGING SYSTEM

B
19
B R 17 B R/B L/R
W W2 W3 R R R
(BLUE)
R B
B L/W L/Y
(BLACK) B
13 (BLUE)
12 L/W

4 14 L/W
R/L R B
B 21 L/W W/Y
L/W
B
B
R
B B B
22 23

8-11
16
R

15 B
5
ON Dg Br/W Ch
Br/R Br/R
OFF L/W W/Y G/Y Br
OPEN
R R LOCK Dg Br/W Ch B
Ch Br/W Dg
Br/L Br/L P
G/Y Br W/Y L/W

6
Br/LBr/R R R/G

7
R R/W

8
Br/R Br/R2

9
B/W R/L Br/L R/B
Y/L G/L R/B
10
R/G B2 B Br/L R/Y
R/W Lg Y/L
11
Br/L Br
CHARGING SYSTEM
 CHARGING SYSTEM

1. AC magneto
3. Rectifier/regulator
12.Battery
13.Main fuse
17.Frame ground

8-12
 CHARGING SYSTEM

EAS27230

TROUBLESHOOTING
The battery is not being charged.
TIP
• Before troubleshooting, remove the following part(s):
1. Storage box
2. Front cowling

1. Check the fuse. NG →

(Main)
Replace the fuse.
Refer to “CHECKING THE FUS-
ES” on page 8-77.

OK ↓
2. Check the battery. NG →
Refer to “CHECKING AND • Clean the battery terminals.
CHARGING THE BATTERY” on • Recharge or replace the battery.
page 8-78.

OK ↓
3. Check the stator coil. NG →
Replace the crankshaft position sen-
Refer to “CHECKING THE STATOR
sor/stator assembly.
COIL” on page 8-85.

OK ↓
4. Check the rectifier/regulator. NG →
Refer to “CHECKING THE RECTI- Replace the rectifier/regulator.
FIER/REGULATOR” on page 8-85.
OK ↓
5. Check the entire charging system NG →
wiring. Properly connect or repair the charging
Refer to “CIRCUIT DIAGRAM” on system wiring.
page 8-11.

OK ↓
The charging system circuit is OK.

8-13
 CHARGING SYSTEM

8-14
 EAS27250
EAS27240

W/R
Gy/B P/W Y/G Br/W L B/W W/R L/Y L/W L/R Sb B/R G B1 W/B
Gy/B W/R R W
2 G/R Y Gy/G Gy/R Gy/B Y/L R/G Gy R/B Lg G/B P B2 O/B O

L/R R/B L/Y G/Y Gy/B

R/B W/Y
W W R L/Y L/R
W W2 W W G/Y R/B (BLUE)
W2 W2 3 G/R Gy/B
W3 W
1 W3 W3 B B
W/R
18 25 32
19 Gy/B R/B
B
B R 17 Gy/R Gy/B Y G/R G/R O O
B R/B L/R 20
W W2 W3 R R A
R (BLACK)
(BLUE) 33 A
Gy/R Gy/R A Gy/R Gy/R
CIRCUIT DIAGRAM

R B
B L/W L/Y
W/Y L/Y 26 Y Y A Y Y L
(BLACK) B Gy/B Gy/R Gy/R Gy/B
Gy/B Gy/B A Gy/B Y
13 (BLUE) Y
12 L/W
L/Y
34
14 O/B R/B R/L O/B WIRE HARNESS SUB-WIRE HARNESS
4 B
L/W
R/L R 21 L/W W/Y Gy/R (BLACK) (BLACK)
LIGHTING SYSTEM

B L/W
B Gy/B P/W Gy/R 27 P/W P/W O/B O/B R/B
B Gy/B
R (BLACK)
B B B
22 23 24
16
Gy/B
R 35
Br/W Gy/B L/W 31 Gy/G Gy/G Gy/B
B
28
5 15 (GREEN)
ON Br/W Br/W B/R B/R R/B
Dg Br/W Ch
Br/R Br/R
OFF L/W W/Y G/Y Br B1 B2 R/B B/R
OPEN W L Gy/G Gy/B
Gy/R
R R LOCK Dg Br/W Ch Br G/Y
Ch Br/W Dg Y/G Y/G (BLACK)
Br/L Br/L P Gy/R Y/G Gy/B 29 Gy/B
G/Y Br W/Y L/W

6 B1 P P
Lg Sb
Br/LBr/R R R/G R/G Lg Lg
36 P G
G G
7 Sb Sb (BLACK)
Gy/R
R R/W Gy Gy/B Gy/R O/R B/W P Gy
30 Gy/B Gy
8
Br/R Br/R2
G/B
9 W/B
B/W R/L Br/L R/B R/B
Y/L G/L R/B Y/L
10
R/G B2 B Br/L R/Y
R/W Lg Y/L
11 B2 B/W
Br/L Br

R/B
Br/R2

8-15
B/W
R/Y R/Y2
76 Y/L
Br/W Br
40 R/Y
R/L R/W Br/R2 38
L/B 39
R/B P
R/Y2 W/B (BLACK)

74 L/B W/B
R/W Br/W
G/L Br
L R Br
R/B G/B
41 L/B R/Y Br/W P 37
B
G B
L G/B
B/W R/L
42 43 44 45 46
L
Y/L Y/L

Y/L B B
L Y G P B G/Y
B/W 75 Y/L R 73
R/L Dg Br/W Ch L/B R/Y Br
(BLACK) (BLACK)
G Y Dg Ch B G/Y Br
G Y G/Y B P
B
Ch Br/W Dg Br R/Y L/B

R/B
60 G/L R/L Y/L Br Y Dg Ch

Br
Sb
Gy
61 62 57 B Sb Br B

54 Ch B Ch Dg Dg B 50 Ch Br G/Y 47 Dg Br G/Y
G Y Br

63 64 65 66 67 68 69 70 71 53 52 51 49 48 49
B 55 55 56 56

Sb Ch Br
B/L B G Br Br W
B B
B/L Gy B G/Y
Ch Dg Y R/B R/L Sb Y B G/Y B
G/L Br Y/L B/L Gy B 58 (BLACK)
59 Sb B B Br G B Dg Br B
72 Br Ch
B Gy B B B Y B G/Y
G/Y B
B2 B1 (BLACK)
B B
B1 B1 B/L
LIGHTING SYSTEM
 LIGHTING SYSTEM

5. Main switch
6. ECU fuse
8. Turn signal/hazard fuse
9. Ignition fuse
10.Headlight fuse
11.Signaling system fuse
12.Battery
13.Main fuse
17.Frame ground
31.ECU (engine control unit)
40.Headlight relay
42.Dimmer switch
43.Pass switch
49.Tail/brake light
55.Headlight
56.Auxiliary light
57.License plate light
68.Meter light
69.High beam indicator light

8-16
 LIGHTING SYSTEM

EAS27260

TROUBLESHOOTING
Any of the following fail to light: headlight, high beam indicator light, taillights, license plate light, auxiliary
lights or meter light.
TIP
• Before troubleshooting, remove the following part(s):
1. Front cowling

1. Check the condition of each bulb NG →

and bulb socket.
Refer to “CHECKING THE BULBS Replace the bulb(s) and bulb socket(s).
AND BULB SOCKETS” on page
8-76.
OK ↓
2. Check the fuses. NG →
(Main, headlight, ignition, ECU, turn
signal/hazard, and signaling sys-
Replace the fuse(s).
tem)
Refer to “CHECKING THE FUS-
ES” on page 8-77.

OK ↓
3. Check the battery. NG →
Refer to “CHECKING AND • Clean the battery terminals.
CHARGING THE BATTERY” on • Recharge or replace the battery.
page 8-78.

OK ↓
4. Check the main switch. NG →
Refer to “CHECKING THE Replace the main switch/immobilizer unit.
SWITCHES” on page 8-73.
OK ↓
5. Check the dimmer switch. NG →
The dimmer switch is faulty. Replace the
Refer to “CHECKING THE
left handlebar switch.
SWITCHES” on page 8-73.

OK ↓
6. Check the pass switch. NG →
The pass switch is faulty. Replace the left
Refer to “CHECKING THE
handlebar switch.
SWITCHES” on page 8-73.

OK ↓
7. Check the headlight relay. NG →
Refer to “CHECKING THE RE- Replace the headlight relay.
LAYS” on page 8-80.
OK ↓

8-17
 LIGHTING SYSTEM

8. Check the entire lighting system NG →

wiring. Properly connect or repair the lighting sys-
Refer to “CIRCUIT DIAGRAM” on tem wiring.
page 8-15.

OK ↓
Replace the ECU or meter assembly.

8-18
 EAS27280
EAS27270

W/R
Gy/B P/W Y/G Br/W L B/W W/R L/Y L/W L/R Sb B/R G B1 W/B
Gy/B W/R R W
2 G/R Y Gy/G Gy/R Gy/B Y/L R/G Gy R/B Lg G/B P B2 O/B O

L/R R/B L/Y G/Y Gy/B

R/B W/Y
W W R L/Y L/R
W W2 W W G/Y R/B (BLUE)
W2 W2 3 G/R Gy/B
W3 W
1 W3 W3 B B
W/R
18 25 32
19 Gy/B R/B
B
B R 17 Gy/R Gy/B Y G/R G/R O O
B R/B L/R 20
W W2 W3 R R A
R (BLACK)
(BLUE) 33 A
Gy/R Gy/R A Gy/R Gy/R
CIRCUIT DIAGRAM

R B
B L/W L/Y
W/Y L/Y 26 Y Y A Y Y L
(BLACK) B Gy/B Gy/R Gy/R Gy/B
Gy/B Gy/B A Gy/B Y
13 (BLUE) Y
12 L/W
L/Y
34
14 O/B R/B R/L O/B WIRE HARNESS SUB-WIRE HARNESS
4 B
L/W
R/L R 21 L/W W/Y Gy/R (BLACK) (BLACK)
B L/W
B Gy/B P/W Gy/R 27 P/W P/W O/B O/B R/B
B Gy/B
R (BLACK)
SIGNALING SYSTEM

B B B
22 23 24
16
Gy/B
R 35
Br/W Gy/B L/W 31 Gy/G Gy/G Gy/B
B
28
5 15 (GREEN)
ON Br/W Br/W B/R B/R R/B
Dg Br/W Ch
Br/R Br/R
OFF L/W W/Y G/Y Br B1 B2 R/B B/R
OPEN W L Gy/G Gy/B
Gy/R
R R LOCK Dg Br/W Ch Br G/Y
Ch Br/W Dg Y/G Y/G (BLACK)
Br/L Br/L P Gy/R Y/G Gy/B 29 Gy/B
G/Y Br W/Y L/W

6 B1 P P
Lg Sb
Br/LBr/R R R/G R/G Lg Lg
36 P G
G G
7 Sb Sb (BLACK)
Gy/R
R R/W Gy Gy/B Gy/R O/R B/W P Gy
30 Gy/B Gy
8
Br/R Br/R2
G/B
9 W/B
B/W R/L Br/L R/B R/B
Y/L G/L R/B Y/L
10
R/G B2 B Br/L R/Y
R/W Lg Y/L
11 B2B/W
Br/L Br

R/B
Br/R2

8-19
B/W
R/Y R/Y2
76 Y/L
Br/W Br
40 R/Y
R/L R/W Br/R2 38
L/B 39
R/B P
R/Y2 W/B (BLACK)

74 L/B W/B
R/W Br/W
G/L Br
L R Br
R/B G/B
41 L/B R/Y Br/W P 37
B
G B
L G/B
B/W R/L
42 43 44 45 46
L
Y/L Y/L

Y/L B B
L Y G P B G/Y
B/W 75 Y/L R 73
R/L Dg Br/W Ch L/B R/Y Br
(BLACK) (BLACK)
G Y Dg Ch B G/Y Br
G Y G/Y B P
B
Ch Br/W Dg Br R/Y L/B

R/B
60 G/L R/L Y/L Br Y Dg Ch

Br
Sb
Gy
61 62 57 B Sb Br B

54 Ch B Ch Dg Dg B 50 Ch Br G/Y 47 Dg Br G/Y
G Y Br

63 64 65 66 67 68 69 70 71 53 52 51 49 48 49
B 55 55 56 56

Sb Ch Br
B/L B G Br Br W
B B
B/L Gy B G/Y
Ch Dg Y R/B R/L Sb Y B G/Y B
G/L Br Y/L B/L Gy B 58 (BLACK)
59 Sb B B Br G B Dg Br B
72 Br Ch
B Gy B B B Y B G/Y
G/Y B
B2 B1 (BLACK)
B B
B1 B1 B/L
SIGNALING SYSTEM
 SIGNALING SYSTEM

2. Crankshaft position sensor

5. Main switch
6. ECU fuse
8. Turn signal/hazard fuse
9. Ignition fuse
11.Signaling system fuse
12.Battery
13.Main fuse
17.Frame ground
23.Hazard switch
24.Front brake light switch
25.Coolant temperature sensor
30.Speed sensor
31.ECU (engine control unit)
38.Horn
39.Turn signal/hazard relay
44.Turn signal switch
45.Horn switch
46.Rear brake light switch
48.Right rear turn signal light
49.Tail/brake light
51.Left rear turn signal light
52.Right front turn signal light
53.Left front turn signal light
58.Fuel sender
59.V-belt replacement indicator reset coupler
62.Multifunction meter
63.Speedometer
64.Tachometer
65.Engine oil change indicator
66.V-belt replacement indicator
70.Right turn signal indicator light
71.Left turn signal indicator light
72.Air temperature sensor
75.Self-diagnosis signal coupler

8-20
 SIGNALING SYSTEM

EAS27290

TROUBLESHOOTING
• Any of the following fail to light: turn signal lights, brake lights, warning light or indicator lights.
• The horn fails to sound.
• The fuel meter fails to operate.
• The coolant temperature meter fails to operate.
• The speedometer fails to operate.
• The tachometer fails to operate.
• The air temperature meter fails to operate.
TIP
• Before troubleshooting, remove the following part(s):
1. Storage box
2. Front cowling

1. Check the fuses. NG →

(Main, signaling system, ignition,
ECU, and turn signal/hazard) Replace the fuse(s).
Refer to “CHECKING THE FUS-
ES” on page 8-77.

OK ↓
2. Check the battery. NG →
Refer to “CHECKING AND • Clean the battery terminals.
CHARGING THE BATTERY” on • Recharge or replace the battery.
page 8-78.

OK ↓
3. Check the main switch. NG →
Refer to “CHECKING THE Replace the main switch/immobilizer unit.
SWITCHES” on page 8-73.

OK ↓
4. Check the entire signaling system NG →
wiring. Properly connect or repair the signaling
Refer to “CIRCUIT DIAGRAM” on system wiring.
page 8-19.

OK ↓
Check the condition of each of the sig-
naling system circuits. Refer to
“Checking the signaling system”.

Checking the signaling system

The horn fails to sound.
1. Check the horn switch. NG →
The horn switch is faulty. Replace the left
Refer to “CHECKING THE
handlebar switch.
SWITCHES” on page 8-73.
OK ↓

8-21
 SIGNALING SYSTEM

2. Check the horn. NG →

Refer to “CHECKING THE HORN” Replace the horn.
on page 8-85.

OK ↓
3. Check the entire signaling system NG →
wiring. Properly connect or repair the signaling
Refer to “CIRCUIT DIAGRAM” on system wiring.
page 8-19.

OK ↓
This circuit is OK.

The tail/brake light fails to come on.

1. Check the tail/brake light bulb and NG →
socket.
Replace the tail/brake light bulb, socket or
Refer to “CHECKING THE BULBS
both.
AND BULB SOCKETS” on page
8-76.

OK ↓
2. Check the front brake light switch. NG →
Refer to “CHECKING THE Replace the front brake light switch.
SWITCHES” on page 8-73.
OK ↓
3. Check the rear brake light switch. NG →
Refer to “CHECKING THE Replace the rear brake light switch.
SWITCHES” on page 8-73.

OK ↓
4. Check the entire signaling system NG →
wiring. Properly connect or repair the signaling
Refer to “CIRCUIT DIAGRAM” on system wiring.
page 8-19.

OK ↓
This circuit is OK.

The turn signal light, turn signal indicator light or both fail to blink.
1. Check the turn signal light bulb and NG →
socket.
Replace the turn signal light bulb, socket or
Refer to “CHECKING THE BULBS
both.
AND BULB SOCKETS” on page
8-76.

OK ↓

8-22
 SIGNALING SYSTEM

2. Check the turn signal switch. NG →

The turn signal switch is faulty. Replace
Refer to “CHECKING THE
the left handlebar switch.
SWITCHES” on page 8-73.

OK ↓
3. Check the hazard switch. NG →
The hazard switch is faulty. Replace the
Refer to “CHECKING THE
right handlebar switch.
SWITCHES” on page 8-73.

OK ↓
4. Check the turn signal/hazard relay. NG →
Refer to “CHECKING THE TURN
Replace the turn signal/hazard relay.
SIGNAL/HAZARD RELAY” on page
8-81.

OK ↓
5. Check the entire signaling system NG →
wiring. Properly connect or repair the signaling
Refer to “CIRCUIT DIAGRAM” on system wiring.
page 8-19.

OK ↓
Replace the meter assembly.

The fuel meter, fuel level warning light, or both fail to come on.
1. Check the fuel sender. NG →
Refer to “CHECKING THE FUEL Replace the fuel sender.
SENDER” on page 8-86.

OK ↓
2. Check the entire signaling system NG →
wiring. Properly connect or repair the signaling
Refer to “CIRCUIT DIAGRAM” on system wiring.
page 8-19.

OK ↓
Replace the meter assembly.

The coolant temperature meter, coolant temperature warning light, or both fail to come on.
1. Check the coolant temperature sen- NG →
sor.
Refer to “CHECKING THE COOL- Replace the coolant temperature sensor.
ANT TEMPERATURE SENSOR”
on page 8-87.

OK ↓

8-23
 SIGNALING SYSTEM

2. Check the entire signaling system NG →

wiring. Properly connect or repair the signaling
Refer to “CIRCUIT DIAGRAM” on system wiring.
page 8-19.
OK ↓
Replace the ECU or meter assembly.

The speedometer fails to operate.

1. Check the speed sensor. NG →
Refer to “CHECKING THE SPEED Replace the speed sensor.
SENSOR” on page 8-87.

OK ↓
2. Check the entire signaling system NG →
wiring. Properly connect or repair the signaling
Refer to “CIRCUIT DIAGRAM” on system wiring.
page 8-19.

OK ↓
Replace the ECU or meter assembly.

The tachometer fails to operate.

1. Check the crankshaft position sen- NG →
sor.
Replace the crankshaft position sen-
Refer to “CHECKING THE CRANK-
sor/stator assembly.
SHAFT POSITION SENSOR” on
page 8-83.

OK ↓
2. Check the entire signaling system NG →
wiring. Properly connect or repair the signaling
Refer to “CIRCUIT DIAGRAM” on system wiring.
page 8-19.

OK ↓
Replace the ECU or meter assembly.

The air temperature meter fails to operate.

1. Check the air temperature sensor. NG →
Refer to “CHECKING THE AIR
Replace the air temperature sensor.
TEMPERATURE SENSOR” on
page 8-89.

OK ↓

8-24
 SIGNALING SYSTEM

2. Check the entire signaling system NG →

wiring. Properly connect or repair the signaling
Refer to “CIRCUIT DIAGRAM” on system wiring.
page 8-19.
OK ↓
Replace the meter assembly.

The V-belt replacement indicator fails to come on.

1. Check the V-belt replacement indi- NG →
cator reset coupler.
Replace the V-belt replacement indicator
Refer to “CHECKING THE V-BELT
reset coupler.
REPLACEMENT INDICATOR RE-
SET COUPLER” on page 8-90.

OK ↓
2. Check the entire signaling system NG →
wiring. Properly connect or repair the signaling
Refer to “CIRCUIT DIAGRAM” on system wiring.
page 8-19.

OK ↓
Replace the meter assembly.

The engine oil change indicator fails to come on.

1. Check the entire signaling system NG →
wiring. Properly connect or repair the signaling
Refer to “CIRCUIT DIAGRAM” on system wiring.
page 8-19.

OK ↓
Replace the meter assembly.

8-25
 SIGNALING SYSTEM

8-26
 EAS27310
EAS27300

W/R
Gy/B P/W Y/G Br/W L B/W W/R L/Y L/W L/R Sb B/R G B1 W/B
Gy/B W/R R W
2 G/R Y Gy/G Gy/R Gy/B Y/L R/G Gy R/B Lg G/B P B2 O/B O

L/R R/B L/Y G/Y Gy/B

R/B W/Y
W W R L/Y L/R
W W2 W W G/Y R/B (BLUE)
W2 W2 3 G/R Gy/B
W3 W
1 W3 W3 B B
W/R
18 25 32
19 Gy/B R/B
B
B R 17 Gy/R Gy/B Y G/R G/R O O
B R/B L/R 20
W W2 W3 R R A
R (BLACK)
(BLUE) 33 A
Gy/R Gy/R A Gy/R Gy/R
CIRCUIT DIAGRAM

R B
B L/W L/Y
W/Y L/Y 26 Y Y A Y Y L
(BLACK) B Gy/B Gy/R Gy/R Gy/B
Gy/B Gy/B A Gy/B Y
13 (BLUE) Y
12 L/W
L/Y
34
14 O/B R/B R/L O/B WIRE HARNESS SUB-WIRE HARNESS
4 B
L/W
COOLING SYSTEM

R/L R 21 L/W W/Y Gy/R (BLACK) (BLACK)

B L/W
B Gy/B P/W Gy/R 27 P/W P/W O/B O/B R/B
B Gy/B
R (BLACK)
B B B
22 23 24
16
Gy/B
R 35
Br/W Gy/B L/W 31 Gy/G Gy/G Gy/B
B
28
5 15 (GREEN)
ON Br/W Br/W B/R B/R R/B
Dg Br/W Ch
Br/R Br/R
OFF L/W W/Y G/Y Br B1 B2 R/B B/R
OPEN W L Gy/G Gy/B
Gy/R
R R LOCK Dg Br/W Ch Br G/Y
Ch Br/W Dg Y/G Y/G (BLACK)
Br/L Br/L P Gy/R Y/G Gy/B 29 Gy/B
G/Y Br W/Y L/W

6 B1 P P
Lg Sb
Br/LBr/R R R/G R/G Lg Lg
36 P G
G G
7 Sb Sb (BLACK)
Gy/R
R R/W Gy Gy/B Gy/R O/R B/W P Gy
30 Gy/B Gy
8
Br/R Br/R2
G/B
9 W/B
B/W R/L Br/L R/B R/B
Y/L G/L R/B Y/L
10
R/G B2 B Br/L R/Y
R/W Lg Y/L
11 B2
Br/L Br
B/W
R/B
Br/R2

8-27
B/W
R/Y R/Y2
76 Y/L
Br/W Br
40 R/Y
R/L R/W Br/R2 38
L/B 39
R/B P
R/Y2 W/B (BLACK)

74 L/B W/B
R/W Br/W
G/L Br
L R Br
R/B G/B
41 L/B R/Y Br/W P 37
B
G B
L G/B
B/W R/L
42 43 44 45 46
L
Y/L Y/L

Y/L B B
L Y G P B G/Y
B/W 75 Y/L R 73
R/L Dg Br/W Ch L/B R/Y Br
(BLACK) (BLACK)
G Y Dg Ch B G/Y Br
G Y G/Y B P
B
Ch Br/W Dg Br R/Y L/B

R/B
60 G/L R/L Y/L Br Y Dg Ch

Br
Sb
Gy
61 62 57 B Sb Br B

54 Ch B Ch Dg Dg B 50 Ch Br G/Y 47 Dg Br G/Y
G Y Br

63 64 65 66 67 68 69 70 71 53 52 51 49 48 49
B 55 55 56 56

Sb Ch Br
B/L B G Br Br W
B B
B/L Gy B G/Y
Ch Dg Y R/B R/L Sb Y B G/Y B
G/L Br Y/L B/L Gy B 58 (BLACK)
59 Sb B B Br G B Dg Br B
72 Br Ch
B Gy B B B Y B G/Y
G/Y B
B2 B1 (BLACK)
B B
B1 B1 B/L
COOLING SYSTEM
 COOLING SYSTEM

5. Main switch
6. ECU fuse
7. Radiator fan motor fuse
9. Ignition fuse
12.Battery
13.Main fuse
17.Frame ground
25.Coolant temperature sensor
31.ECU (engine control unit)
73.Radiator fan motor
74.Radiator fan motor relay

8-28
 COOLING SYSTEM

EAS27320

TROUBLESHOOTING
• The radiator fan motor fails to turn.
TIP
• Before troubleshooting, remove the following part(s):
1. Storage box
2. Front cowling
3. Radiator cover

1. Check the fuses. NG →

(Main, ignition, ECU, and radiator
fan motor) Replace the fuse(s).
Refer to “CHECKING THE FUS-
ES” on page 8-77.

OK ↓
2. Check the battery. NG →
Refer to “CHECKING AND • Clean the battery terminals.
CHARGING THE BATTERY” on • Recharge or replace the battery.
page 8-78.

OK ↓
3. Check the main switch. NG →
Refer to “CHECKING THE Replace the main switch/immobilizer unit.
SWITCHES” on page 8-73.
OK ↓
4. Check the radiator fan motor. NG →
Refer to “CHECKING THE RADIA- Replace the radiator fan motor.
TOR FAN MOTOR” on page 8-87.

OK ↓
5. Check the radiator fan motor relay. NG →
Refer to “CHECKING THE RE- Replace the radiator fan motor relay.
LAYS” on page 8-80.

OK ↓
6. Check the coolant temperature sen- NG →
sor.
Refer to “CHECKING THE COOL- Replace the coolant temperature sensor.
ANT TEMPERATURE SENSOR”
on page 8-87.

OK ↓
7. Check the entire cooling system NG →
wiring. Properly connect or repair the cooling sys-
Refer to “CIRCUIT DIAGRAM” on tem wiring.
page 8-27.

OK ↓
Replace the ECU.

8-29
 COOLING SYSTEM

8-30
 EAS27340
EAS27330

W/R
Gy/B P/W Y/G Br/W L B/W W/R L/Y L/W L/R Sb B/R G B1 W/B
Gy/B W/R R W
2 G/R Y Gy/G Gy/R Gy/B Y/L R/G Gy R/B Lg G/B P B2 O/B O

L/R R/B L/Y G/Y Gy/B

R/B W/Y
W W R L/Y L/R
W W2 W W G/Y R/B (BLUE)
W2 W2 3 G/R Gy/B
W3 W
1 W3 W3 B B
W/R
18 25 32
19 Gy/B R/B
B
B R 17 Gy/R Gy/B Y G/R G/R O O
B R/B L/R 20
W W2 W3 R R A
R (BLACK)
(BLUE) 33 A
Gy/R Gy/R A Gy/R Gy/R
CIRCUIT DIAGRAM

R B
B L/W L/Y
W/Y L/Y 26 Y Y A Y Y L
(BLACK) B Gy/B Gy/R Gy/R Gy/B
Gy/B Gy/B A Gy/B Y
13 (BLUE) Y
12 L/W
L/Y
34
14 O/B R/B R/L O/B WIRE HARNESS SUB-WIRE HARNESS
4 B
L/W
R/L R 21 L/W W/Y Gy/R (BLACK) (BLACK)
B L/W
B Gy/B P/W Gy/R 27 P/W P/W O/B O/B R/B
B Gy/B
R (BLACK)
B B B
22 23 24
16
Gy/B
R 35
Br/W Gy/B L/W 31 Gy/G Gy/G Gy/B
B
28
5 15 (GREEN)
ON Br/W Br/W B/R B/R R/B
Dg Br/W Ch
Br/R Br/R
OFF L/W W/Y G/Y Br B1 B2 R/B B/R
OPEN W L Gy/G Gy/B
Gy/R
R R LOCK Dg Br/W Ch Br G/Y
Y/G
FUEL INJECTION SYSTEM

Ch Br/W Dg 29 Y/G (BLACK)

Br/L Br/L P Gy/R Y/G Gy/B
G/Y Br W/Y L/W Gy/B

6 B1 P P
Lg Sb
Br/LBr/R R R/G R/G Lg Lg
36 P G
G G
7 Sb Sb (BLACK)
Gy/R
R R/W Gy Gy/B Gy/R O/R B/W P Gy
30 Gy/B Gy
8
Br/R Br/R2
G/B
9 W/B
B/W R/L Br/L R/B R/B
Y/L G/L R/B Y/L
10
R/G B2 B Br/L R/Y
R/W Lg Y/L
11 B2 B/W
Br/L Br

R/B
Br/R2

8-31
B/W
R/Y R/Y2
76 Y/L
Br/W Br
40 R/Y
R/L R/W Br/R2 38
L/B 39
R/B P
R/Y2 W/B (BLACK)

74 L/B W/B
R/W Br/W
G/L Br
L R Br
R/B G/B
41 L/B R/Y Br/W P 37
B
G B
L G/B
B/W R/L
42 43 44 45 46
L
Y/L Y/L

Y/L B B
L Y G P B G/Y
B/W 75 Y/L R 73
R/L Dg Br/W Ch L/B R/Y Br
(BLACK) (BLACK)
G Y Dg Ch B G/Y Br
G Y G/Y B P
B
Ch Br/W Dg Br R/Y L/B

R/B
60 G/L R/L Y/L Br Y Dg Ch

Br
Sb
Gy
61 62 57 B Sb Br B

54 Ch B Ch Dg Dg B 50 Ch Br G/Y 47 Dg Br G/Y
G Y Br

63 64 65 66 67 68 69 70 71 53 52 51 49 48 49
B 55 55 56 56

Sb Ch Br
B/L B G Br Br W
B B
B/L Gy B G/Y
Ch Dg Y R/B R/L Sb Y B G/Y B
G/L Br Y/L B/L Gy B 58 (BLACK)
59 Sb B B Br G B Dg Br B
72 Br Ch
B Gy B B B Y B G/Y
G/Y B
B2 B1 (BLACK)
B B
B1 B1 B/L
FUEL INJECTION SYSTEM
 FUEL INJECTION SYSTEM

2. Crankshaft position sensor

4. Backup fuse (immobilizer unit and meter
assembly)
5. Main switch
6. ECU fuse
7. Radiator fan motor fuse
9. Ignition fuse
10.Headlight fuse
12.Battery
13.Main fuse
17.Frame ground
18.Sidestand switch
19.Fuel pump
25.Coolant temperature sensor
26.Throttle position sensor
27.Intake air pressure sensor
28.Intake air temperature sensor
29.Lean angle sensor
30.Speed sensor
31.ECU (engine control unit)
32.Ignition coil
33.Spark plug
34.Fuel injector
35.O2 sensor
36.ISC (idle speed control) unit
40.Headlight relay
62.Multifunction meter
67.Engine trouble warning light
73.Radiator fan motor
74.Radiator fan motor relay
75.Self-diagnosis signal coupler
A. YP250R only

8-32
 FUEL INJECTION SYSTEM

EAS27350

ECU SELF-DIAGNOSTIC FUNCTION

The ECU is equipped with a self-diagnostic function in order to ensure that the fuel injection system is
operating normally. If this function detects a malfunction in the system, it immediately operates the en-
gine under substitute characteristics and illuminates the engine trouble warning light to alert the rider
that a malfunction has occurred in the system. Once a malfunction has been detected, a fault code is
stored in the memory of the ECU.
• To inform the rider that the fuel injection system is not functioning, the engine trouble warning light
flashes when the start switch is being pushed to start the engine.
• If a malfunction is detected in the system by the self-diagnostic function, the ECU provides an appro-
priate substitute characteristic operation, and alerts the rider of the detected malfunction by illuminat-
ing the engine trouble warning light.
• After the engine has been stopped, the lowest fault code number appears on the odometer LCD.
Once a fault code has been displayed, it remains stored in the memory of the ECU until it is deleted.

Engine trouble warning light indication and fuel injection system operation
Warning light indica-
ECU operation FI operation Vehicle operation
tion
Warning provided
Flashing* when unable to start Operation stopped Cannot be operated
engine
Operated with substi-
tute characteristics in Can or cannot be oper-
Remains on Malfunction detected accordance with the ated depending on the
description of the mal- fault code
function

* The warning light flashes when any one of the conditions listed below is present and the start switch
is pushed:
Lean angle sensor
12: Crankshaft position sensor 30:
(latch up detected)
Intake air pressure sensor
13: 33: Faulty ignition
(open or short circuit)
Intake air pressure sensor Fuel injector
14: 39:
(clogged or detached hose) (open or short circuit)
Throttle position sensor Lean angle sensor
15: 41:
(open or short circuit) (open or short circuit)
Throttle position sensor ECU internal malfunction
16: 50:
(stuck) (memory check error)
Blue/yellow ECU lead
19:
(broken or disconnected)

Checking for a defective engine trouble warning light

The engine trouble warning light comes on for 2.0 seconds after the main switch has been set to “ON”
and when the start switch is being pushed. If the warning light does not come on under these conditions,
the warning light bulb may be defective.

ECU detects an abnormal signal from a sensor

If the ECU detects an abnormal signal from a sensor while the vehicle is being driven, the ECU illumi-
nates the engine trouble warning light and provides the engine with alternate operating instructions that
are appropriate for the type of malfunction.

8-33
 FUEL INJECTION SYSTEM

When an abnormal signal is received from a sensor, the ECU processes the specified values that are
programmed for each sensor in order to provide the engine with alternate operating instructions that
enable the engine to continue operating or stop operating, depending on the conditions.
EAS27400
3. Perform the reinstatement action for the fuel
TROUBLESHOOTING METHOD
injection system.
Refer to “Reinstatement method” in the ap-
The engine operation is not normal and the
propriate table in “TROUBLESHOOTING
engine trouble warning light comes on.
DETAILS” on page 8-36.
1. Check:
4. Set the main switch to “OFF”, then to “ON”
• Fault code number
again, and then check that no fault code num-
▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼
a. Check the fault code number displayed on ber is displayed.
the meter. TIP
b. Identify the faulty system with the fault code If another fault code number is displayed, repeat
number. steps (1) to (4) until no fault code number is dis-
c. Identify the probable cause of the malfunc- played.
tion.
5. Erase the malfunction history in the diagnos-
▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲
tic mode. Refer to “DIAGNOSTIC CODE TA-
2. Check and repair the probable cause of the BLE” on page 8-54 (Diagnostic code No. 62).
malfunction.
TIP
Fault code No. No fault code No. Setting the main switch to “OFF” will not erase
Check and repair. Check and repair. the malfunction history.
Refer to “TROUBLE-
SHOOTING DE- The engine operation is not normal, but the
TAILS” on page 8-36.
engine trouble warning light does not come
Monitor the opera-
tion of the sensors on.
and actuators in the 1. Check the operation of the following sensors
diagnostic mode. Re- and actuators in the Diagnostic mode. Refer
fer to “TROUBLE- to “TROUBLESHOOTING DETAILS” on
SHOOTING page 8-36.
DETAILS” on page 01: Throttle position sensor (throttle angle)
8-36 and “DIAGNOS- 30: Ignition coil
TIC CODE TABLE” 36: Fuel injector
on page 8-54.
If a malfunction is detected in the sensors or
actuators, repair or replace all faulty parts.
If no malfunction is detected in the sensors
and actuators, check and repair the inner
parts of the engine.
EAS27441

DIAGNOSTIC MODE
It is only possible to monitor the sensor output data or check the activation of actuators by connecting
the FI diagnostic tool to the vehicle and setting the diagnostic mode.
TIP
The diagnostic mode can only be set using the FI diagnostic tool. The diagnostic mode cannot be set
using the meter.

FI diagnostic tool
90890-03182

8-34
 FUEL INJECTION SYSTEM

Setting the diagnostic mode

1. Set the main switch to “OFF”.
2. Disconnect the self-diagnosis signal coupler, and then connect the FI diagnostic tool “1” as shown.
1

3. While pressing the “MODE” button, set the main switch to “ON”.
TIP
• “DIAG” appears on the LCD of the FI diagnostic tool. If “CO” appears on the LCD of the FI diagnostic
tool, press the “UP” button to select “DIAG”.
• The “POWER” LED (green) comes on.
4. Press the “MODE” button.
TIP
The diagnostic code number “D01” appears on the LCD of the FI diagnostic tool.
5. Select the diagnostic code number corresponding to the fault code number by pressing the “UP” and
“DOWN” buttons.
TIP
• The diagnostic code number appears on the LCD (01-70).
• To decrease the selected diagnostic code number, press the “DOWN” button. Press the “DOWN” but-
ton for 1 second or longer to automatically decrease the diagnostic code numbers.
• To increase the selected diagnostic code number, press the “UP” button. Press the “UP” button for 1
second or longer to automatically increase the diagnostic code numbers.

6. Check the operation of the sensor or actuator.

• Sensor operation
The data representing the operating conditions of the sensor appear on the LCD.
• Actuator operation
Press the “MODE” button.
7. Set the main switch to “OFF” to cancel the diagnostic mode.
8. Disconnect the FI diagnostic tool and connect the self-diagnosis signal coupler.
TIP
Information about each diagnostic code number is organized in this manual as follows:
• If a diagnostic code number has a corresponding fault code number, the information is shown in
“TROUBLESHOOTING DETAILS”. (Refer to “TROUBLESHOOTING DETAILS” on page 8-36.)

8-35
 FUEL INJECTION SYSTEM

• If a diagnostic code number does not have a corresponding fault code number, the information is
shown in “DIAGNOSTIC CODE TABLE”. (Refer to “DIAGNOSTIC CODE TABLE” on page 8-54.)

EAS27481

TROUBLESHOOTING DETAILS
This section describes the measures per fault code number displayed on the meter. Check and service
the items or components that are the probable cause of the malfunction following the order given.
After the check and service of the malfunctioning part have been completed, reset the meter display
according to the reinstatement method.
Fault code No.:
Fault code number displayed on the meter when the engine failed to work normally.
Diagnostic code No.:
Diagnostic code number to be used when the diagnostic mode is operated. Refer to “DIAGNOSTIC
MODE” on page 8-34.

Fault code No. 12

Crankshaft position sensor: no normal signals are received
Item
from the crankshaft position sensor.
Unable to start engine
Fail-safe system
Unable to drive vehicle
Diagnostic code No. —
FI diagnostic tool display —
Checking method —
Probable cause of malfunction Check or maintenance job
1 Installed condition of crankshaft position • Check for looseness or pinching.
sensor.
2 Connections • Check the coupler for any pins that may be
• Crankshaft position sensor coupler pulled out.
• Wire harness ECU coupler • Check the locking condition of the coupler.
• If there is a malfunction, repair it and connect
the coupler securely.
3 Open or short circuit in wire harness. • Repair or replace if there is an open or short
circuit.
• Between the crankshaft position sensor cou-
pler and ECU coupler.
(gray/black–gray/black)
(white/red–white/red)
4 Defective crankshaft position sensor. • Replace if defective.
Refer to “CHECKING THE CRANKSHAFT
POSITION SENSOR” on page 8-83.
Reinstatement method Cranking the engine.

8-36
 FUEL INJECTION SYSTEM

Fault code No. 13

Item Intake air pressure sensor: open or short circuit detected.
Able to start engine
Fail-safe system
Able to drive vehicle
Diagnostic code No. 03
FI diagnostic tool display Displays the intake air pressure.
Operate the throttle while pulling the brake lever and pushing the
Checking method start switch “ ”. (If the display value changes, the performance is
OK.)
Probable cause of malfunction Check or maintenance job
1 Connections • Check the coupler for any pins that may be
• Intake air pressure sensor coupler pulled out.
• Wire harness ECU coupler • Check the locking condition of the coupler.
• If there is a malfunction, repair it and connect
the coupler securely.
2 Open or short circuit in wire harness. • Repair or replace if there is an open or short
circuit.
• Between intake air pressure sensor coupler
and ECU coupler.
(gray/red–gray/red)
(pink/white–pink/white)
(gray/black–gray/black)
3 Defective intake air pressure sensor. • Execute the diagnostic mode. (Code No. 03)
• Replace if defective.
Refer to “CHECKING THE INTAKE AIR
PRESSURE SENSOR” on page 8-88.
Reinstatement method Turning the main switch to “ON”.

Fault code No. 14

Intake air pressure sensor: hose line malfunction (clogged or
Item
detached hose).
Able to start engine
Fail-safe system
Able to drive vehicle
Diagnostic code No. 03
FI diagnostic tool display Displays the intake air pressure.
Operate the throttle while pulling the brake lever and pushing the
Checking method start switch “ ”. (If the display value changes, the performance is
OK.)
Probable cause of malfunction Check or maintenance job
1 Intake air pressure sensor hose • Check the intake air pressure sensor hose
condition.
• Repair or replace the sensor hose.
2 Intake air pressure sensor malfunction at • Check and repair the connection.
intermediate electrical potential. • Replace it if there is a malfunction.

8-37
 FUEL INJECTION SYSTEM

Fault code No. 14

Intake air pressure sensor: hose line malfunction (clogged or
Item
detached hose).
3 Connections • Check the coupler for any pins that may be
• Intake air pressure sensor coupler pulled out.
• Wire harness ECU coupler • Check the locking condition of the coupler.
• If there is a malfunction, repair it and connect
the coupler securely.
4 Defective intake air pressure sensor. • Execute the diagnostic mode. (Code No. 03)
• Replace if defective.
Refer to “CHECKING THE INTAKE AIR
PRESSURE SENSOR” on page 8-88.
Reinstatement method Starting the engine and operating it at idle.

Fault code No. 15

Item Throttle position sensor: open or short circuit detected.
Able to start engine
Fail-safe system
Able to drive vehicle
Diagnostic code No. 01
Throttle angle
FI diagnostic tool display • 9–22 (fully closed position)
• 93–106 (fully opened position)
• Check with throttle fully closed.
Checking method
• Check with throttle fully opened.
Probable cause of malfunction Check or maintenance job
1 Installed condition of throttle position • Check for looseness or pinching.
sensor. • Check that the sensor is installed in the speci-
fied position.
2 Connections • Check the coupler for any pins that may be
• Throttle position sensor coupler pulled out.
• Wire harness ECU coupler • Check the locking condition of the coupler.
• If there is a malfunction, repair it and connect
the coupler securely.
3 Open or short circuit in wire harness. • Repair or replace if there is an open or short
circuit.
• Between throttle position sensor coupler and
ECU coupler.
(gray/red–gray/red)
(yellow–yellow)
(gray/black–gray/black)
4 Defective throttle position sensor. • Execute the diagnostic mode. (Code No. 01)
• Replace if defective.
Refer to “CHECKING THE THROTTLE POSI-
TION SENSOR” on page 8-88.
Reinstatement method Turning the main switch to “ON”.

8-38
 FUEL INJECTION SYSTEM

Fault code No. 16

Throttle position sensor: stuck throttle position sensor is de-
Item
tected.
Able to start engine
Fail-safe system
Able to drive vehicle
Diagnostic code No. 01
Throttle angle
FI diagnostic tool display • 9–22 (fully closed position)
• 93–106 (fully opened position)
• Check with throttle fully closed.
Checking method
• Check with throttle fully opened.
Probable cause of malfunction Check or maintenance job
1 Installed condition of throttle position • Check for looseness or pinching.
sensor. • Check that the sensor is installed in the speci-
fied position.
2 Defective throttle position sensor. • Execute the diagnostic mode. (Code No. 01)
• Replace if defective.
Refer to “CHECKING THE THROTTLE POSI-
TION SENSOR” on page 8-88.
Reinstatement method Turning the main switch to “ON”.

Fault code No. 19

Sidestand switch: a break or disconnection of the blue/yellow
Item
lead of the ECU is detected.
Unable to start engine
Fail-safe system
Unable to drive vehicle
Diagnostic code No. 20
Sidestand switch
FI diagnostic tool display • ON (stand retracted)
• OFF (stand extended)
Checking method Extend and retract the sidestand.
Probable cause of malfunction Check or maintenance job
1 Connections • Check the coupler for any pins that may be
• Wire harness ECU coupler pulled out.
• Check the locking condition of the coupler.
• If there is a malfunction, repair it and connect
the coupler securely.
2 Open or short circuit in wire harness. • Repair or replace if there is an open or short
circuit.
• Between ECU and blue/yellow lead.
3 Defective sidestand switch. • Execute the diagnostic mode. (Code No. 20)
• Replace if defective.
Refer to “CHECKING THE SWITCHES” on
page 8-73.

8-39
 FUEL INJECTION SYSTEM

Fault code No. 19

Sidestand switch: a break or disconnection of the blue/yellow
Item
lead of the ECU is detected.
Reinstatement method Reconnecting the wiring and retracting the sidestand.

Fault code No. 21

Item Coolant temperature sensor: open or short circuit detected.
Able to start engine
Fail-safe system
Able to drive vehicle
Diagnostic code No. 06
FI diagnostic tool display Displays the coolant temperature.
Compare the actually measured coolant temperature with the FI
Checking method
diagnostic tool display value.
Probable cause of malfunction Check or maintenance job
1 Installed condition of coolant tempera- • Check for looseness or pinching.
ture sensor.
2 Connections • Check the coupler for any pins that may be
• Coolant temperature sensor coupler pulled out.
• Wire harness ECU coupler • Check the locking condition of the coupler.
• If there is a malfunction, repair it and connect
the coupler securely.
3 Open or short circuit in wire harness. • Repair or replace if there is an open or short
circuit.
• Between coolant temperature sensor coupler
and ECU coupler.
(green/red–green/red)
(gray/black–gray/black)
4 Defective coolant temperature sensor. • Execute the diagnostic mode. (Code No. 06)
• Replace if defective.
Refer to “CHECKING THE COOLANT TEM-
PERATURE SENSOR” on page 8-87.
Reinstatement method Turning the main switch to “ON”.

Fault code No. 22

Item Intake air temperature sensor: open or short circuit detected.
Able to start engine
Fail-safe system
Able to drive vehicle
Diagnostic code No. 05
FI diagnostic tool display Displays the intake air temperature.
Compare the actually measured intake air temperature with the FI
Checking method
diagnostic tool display value.
Probable cause of malfunction Check or maintenance job

8-40
 FUEL INJECTION SYSTEM

Fault code No. 22

Item Intake air temperature sensor: open or short circuit detected.
1 Installed condition of intake air tempera- • Check for looseness or pinching.
ture sensor.
2 Connections • Check the coupler for any pins that may be
• Intake air temperature sensor coupler pulled out.
• Wire harness ECU coupler • Check the locking condition of the coupler.
• If there is a malfunction, repair it and connect
the coupler securely.
3 Open or short circuit in wire harness. • Repair or replace if there is an open or short
circuit.
• Between intake air temperature sensor coupler
and ECU coupler.
(gray/black–gray/black)
(brown/white–brown/white)
4 Defective intake air temperature sensor. • Execute the diagnostic mode. (Code No. 05)
• Replace if defective.
Refer to “CHECKING THE INTAKE AIR TEM-
PERATURE SENSOR” on page 8-89.
Reinstatement method Turning the main switch to “ON”.

Fault code No. 24

Item O2 sensor: no normal signal is received from the O2 sensor.

Able to start engine
Fail-safe system
Able to drive vehicle
Diagnostic code No. —
FI diagnostic tool display —
Checking method —
Probable cause of malfunction Check or maintenance job
1 Installed condition of O2 sensor. • Check for looseness or pinching.
2 Connections • Check the coupler for any pins that may be
• O2 sensor coupler pulled out.
• Wire harness ECU coupler • Check the locking condition of the coupler.
• If there is a malfunction, repair it and connect
the coupler securely.
3 Open or short circuit in wire harness. • Repair or replace if there is an open or short
circuit.
• Between O2 sensor coupler and ECU coupler.
(gray/green–gray/green)
(gray/black–gray/black)
(black/red–black/red)
(red/black–red/black)
4 Check fuel pressure. • Refer to “CHECKING THE FUEL PRESSURE”
on page 7-3.
5 Defective O2 sensor. • Replace if defective.

8-41
 FUEL INJECTION SYSTEM

Fault code No. 24

Item O2 sensor: no normal signal is received from the O2 sensor.

Reinstatement method Starting the engine and operating it at idle.

Fault code No. 30

Latch up detected.
Item
No normal signal is received from the lean angle sensor.
Unable to start engine
Fail-safe system
Unable to drive vehicle
Diagnostic code No. 08
Lean angle sensor
FI diagnostic tool display • 0.4–1.4 (upright)
• 3.7–4.4 (overturned)
Remove the lean angle sensor and incline it more than 45 de-
Checking method
grees.
Probable cause of malfunction Check or maintenance job
1 The vehicle has overturned. • Raise the vehicle upright.
2 Installed condition of the lean angle sen- • Check the installed direction and condition of
sor. the sensor.
3 Connections • Check the coupler for any pins that may be
• Lean angle sensor coupler pulled out.
• Wire harness ECU coupler • Check the locking condition of the coupler.
• If there is a malfunction, repair it and connect
the coupler securely.
4 Defective lean angle sensor. • Execute the diagnostic mode. (Code No. 08)
• Replace if defective.
Refer to “CHECKING THE LEAN ANGLE
SENSOR” on page 8-84.
Turning the main switch to “ON” (however, the engine cannot be
Reinstatement method
restarted unless the main switch is first turned “OFF”).

Fault code No. 31

O2 sensor: The amount of air-fuel ratio feedback compensa-
Item tion is maintained continuously in the vicinity of the upper lim-
it.
Able to start engine
Fail-safe system
Able to drive vehicle
Diagnostic code No. —
FI diagnostic tool display —
Checking method —
Probable cause of malfunction Check or maintenance job

8-42
 FUEL INJECTION SYSTEM

Fault code No. 31

O2 sensor: The amount of air-fuel ratio feedback compensa-
Item tion is maintained continuously in the vicinity of the upper lim-
it.
1 Installed condition of O2 sensor. • Check for looseness or pinching.
2 Connections • Check the coupler for any pins that may be
• O2 sensor coupler pulled out.
• Wire harness ECU coupler • Check the locking condition of the coupler.
• If there is a malfunction, repair it and connect
the coupler securely.
3 Open or short circuit in wire harness. • Repair or replace if there is an open or short
circuit.
• Between O2 sensor coupler and ECU coupler.
(gray/green–gray/green)
(gray/black–gray/black)
(black/red–black/red)
(red/black–red/black)
4 Check fuel pressure. • Refer to “CHECKING THE FUEL PRESSURE”
on page 7-3.
5 Defective O2 sensor. • Replace if defective.
Reinstatement method Starting the engine and operating it at idle.

Fault code No. 32

O2 sensor: The amount of air-fuel ratio feedback compensa-
Item tion is maintained continuously in the vicinity of the lower lim-
it.
Able to start engine
Fail-safe system
Able to drive vehicle
Diagnostic code No. —
FI diagnostic tool display —
Checking method —
Probable cause of malfunction Check or maintenance job
1 Installed condition of O2 sensor. • Check for looseness or pinching.
2 Connections • Check the coupler for any pins that may be
• O2 sensor coupler pulled out.
• Wire harness ECU coupler • Check the locking condition of the coupler.
• If there is a malfunction, repair it and connect
the coupler securely.
3 Open or short circuit in wire harness. • Repair or replace if there is an open or short
circuit.
• Between O2 sensor coupler and ECU coupler.
(gray/green–gray/green)
(gray/black–gray/black)
(black/red–black/red)
(red/black–red/black)

8-43
 FUEL INJECTION SYSTEM

Fault code No. 32

O2 sensor: The amount of air-fuel ratio feedback compensa-
Item tion is maintained continuously in the vicinity of the lower lim-
it.
4 Check fuel pressure. • Refer to “CHECKING THE FUEL PRESSURE”
on page 7-3.
5 Defective O2 sensor. • Replace if defective.
Reinstatement method Starting the engine and operating it at idle.

Fault code No. 33

Ignition coil: open or short circuit detected in the primary lead
Item
of the ignition coil.
Unable to start engine
Fail-safe system
Unable to drive vehicle
Diagnostic code No. 30
Actuates the ignition coil five times at one-second intervals.
Actuation Illuminates the “WARNING” LED on the FI diagnostic tool and the
engine trouble warning light.
Check the spark five times.
Checking method
• Connect an ignition checker.
Probable cause of malfunction Check or maintenance job
1 Connections • Check the connector and coupler for any pins
• Ignition coil connector (primary coil that may be pulled out.
side) • Check the locking condition of the connector
• Wire harness ECU coupler and coupler.
• If there is a malfunction, repair it and connect
the coupler or connector securely.
2 Open or short circuit in wire harness. • Repair or replace if there is an open or short
circuit.
• Between ignition coil connector and ECU cou-
pler.
(orange–orange)
(red/black–red/black)
3 Defective ignition coil. • Execute the diagnostic mode. (Code No. 30)
• Test the primary and secondary coils for conti-
nuity.
• Replace if defective.
Refer to “CHECKING THE IGNITION COIL” on
page 8-82.
Reinstatement method Starting the engine and operating it at idle.

8-44
 FUEL INJECTION SYSTEM

Fault code No. 37

Item ISC valve: engine speed is high when the engine is idling.
Able to start engine
Fail-safe system
Able to drive vehicle
Diagnostic code No. 54
Actuates and fully closes the ISC valve, then opens it to the stand-
by opening position when the engine is started.
Actuation
This operation takes approximately 12 seconds until it is complet-
ed.
Checking method The ISC unit vibrates when the ISC valve operates.
Probable cause of malfunction Check or maintenance job
1 Throttle valve does not fully close. • Check the throttle body.
Refer to “THROTTLE BODY” on page 7-5.
• Check the throttle cables.
Refer to “ADJUSTING THE THROTTLE CA-
BLE FREE PLAY” on page 3-9 and “ADJUST-
ING THE THROTTLE CABLE FREE PLAY” on
page 3-23.
2 ISC valve is stuck fully open due to dis- • Check that the ISC unit coupler is not discon-
connected ISC unit coupler. (High engine nected.
idle speed is detected with the ISC valve • The ISC valve is stuck fully open if it does not
stuck fully open even though signals for operate when the main switch is turned “OFF”.
the valve to close are continuously being (Touch the ISC unit with your hand and check
transmitted by the ECU.) if it is vibrating to confirm if the ISC valve is op-
erating.)
3 ISC valve is not moving correctly. • Execute the diagnostic mode. (Code No. 54)
• After the ISC valve is fully closed, it opens to
the standby opening position when the engine
is started. This operation takes approximately
12 seconds. Start the engine. If the error re-
curs, replace the throttle body assembly.
ISC valve returns to its original position by turning the main switch
to “ON” and back to “OFF”.
Reinstatement method
Reinstated if the engine idle speed is within specification after
starting the engine.

Fault code No. 39

Item Injector: open or short circuit detected.
Unable to start engine
Fail-safe system
Unable to drive vehicle
Diagnostic code No. 36
Actuates the injector five times at one-second intervals.
Actuation Illuminates the “WARNING” LED on the FI diagnostic tool and the
engine trouble warning light.
Check that the injector actuates five times by listening to the oper-
Checking method
ating sound.

8-45
 FUEL INJECTION SYSTEM

Fault code No. 39

Item Injector: open or short circuit detected.
Probable cause of malfunction Check or maintenance job
1 Connections • Check the couplers for any pins that may be
• Injector coupler pulled out.
• Wire harness ECU coupler • Check the locking condition of the couplers.
• If there is a malfunction, repair it and connect
the coupler securely.
2 Open or short circuit in wire harness. • Repair or replace if there is an open or short
circuit.
• Between injector coupler and ECU coupler.
(red/black–red/black)
(orange/black–orange/black)
3 Defective injector. • Execute the diagnostic mode. (Code No. 36)
• Replace if defective.
Refer to “CHECKING THE FUEL INJECTOR”
on page 7-9.
Reinstatement method Cranking the engine. (Connect the fuel injector coupler.)

Fault code No. 41

Item Lean angle sensor: open or short circuit detected.
Unable to start engine
Fail-safe system
Unable to drive vehicle
Diagnostic code No. 08
Lean angle sensor
FI diagnostic tool display • 0.4–1.4 (upright)
• 3.7–4.4 (overturned)
Remove the lean angle sensor and incline it more than 45 de-
Checking method
grees.
Probable cause of malfunction Check or maintenance job
1 Connections • Check the coupler for any pins that may be
• Lean angle sensor coupler pulled out.
• Wire harness ECU coupler • Check the locking condition of the coupler.
• If there is a malfunction, repair it and connect
the coupler securely.
2 Open or short circuit in wire harness. • Repair or replace if there is an open or short
circuit.
• Between lean angle sensor coupler and ECU
coupler.
(gray/red–gray/red)
(yellow/green–yellow/green)
(gray/black–gray/black)
3 Defective lean angle sensor. • Execute the diagnostic mode. (Code No. 08)
• Replace if defective.
Refer to “CHECKING THE LEAN ANGLE
SENSOR” on page 8-84.
Reinstatement method Turning the main switch to “ON”.

8-46
 FUEL INJECTION SYSTEM

Fault code No. 42

Speed sensor: no normal signals are received from the speed
Item
sensor.
Able to start engine
Fail-safe system
Able to drive vehicle
Diagnostic code No. 07
FI diagnostic tool display 0–999
Check that the number increases when the front wheel is rotated.
Checking method The number is cumulative and does not reset each time the wheel
is stopped.
Probable cause of malfunction Check or maintenance job
1 Connections • Check the coupler for any pins that may be
• Speed sensor coupler pulled out.
• Wire harness ECU coupler • Check the locking condition of the coupler.
• If there is a malfunction, repair it and connect
the coupler securely.
2 Open or short circuit in wire harness. • Repair or replace if there is an open or short
circuit.
• Between speed sensor coupler and ECU cou-
pler.
(gray/red–gray/red)
(gray–gray)
(gray/black–gray/black)
3 Defective speed sensor. • Execute the diagnostic mode. (Code No. 07)
• Replace if defective.
Refer to “CHECKING THE SPEED SENSOR”
on page 8-87.
4 This fault code will appear on the multi- —
function display if the vehicle speed is
less than 2 km/h, the throttle is opened
70 degrees or more, and the engine
speed exceeds 7000 r/min with the vehi-
cle on the centerstand. This, therefore,
does not indicate a malfunction.
Starting the engine, and inputting the vehicle speed signals by op-
Reinstatement method
erating the vehicle at a 20 to 30 km/h.

Fault code No. 43

Fuel system voltage: the ECU is unable to monitor the battery
Item
voltage (an open or short circuit in the line to the ECU).
Able to start engine
Fail-safe system
Able to drive vehicle
Diagnostic code No. 09
FI diagnostic tool display Approximately 12.0

8-47
 FUEL INJECTION SYSTEM

Fault code No. 43

Fuel system voltage: the ECU is unable to monitor the battery
Item
voltage (an open or short circuit in the line to the ECU).
Compare with the actually measured battery voltage. (If the bat-
Checking method
tery voltage is low, perform recharging.)
Probable cause of malfunction Check or maintenance job
1 Connections • Check the coupler for any pins that may be
• Wire harness ECU coupler pulled out.
• Main switch coupler • Check the locking condition of the coupler.
• If there is a malfunction, repair it and connect
the coupler securely.
2 Open or short circuit in the wire harness. • Repair or replace if there is an open or short
circuit.
• Between battery terminal and main switch
coupler.
(red–red)
• Between main switch coupler and ignition fuse
terminal.
(brown/blue–brown/blue)
• Between ignition fuse terminal and ECU cou-
pler.
(red/black–red/black)
3 Malfunction or open circuit in fuel sys- • Execute the diagnostic mode. (Code No. 09)
tem.
Reinstatement method Starting the engine and operating it at idle.

Fault code No. 44

EEPROM fault code No.: an error is detected while reading or
Item
writing on EEPROM (CO adjustment value).
Able to start engine
Fail-safe system
Able to drive vehicle
Diagnostic code No. 60
EEPROM fault code display
FI diagnostic tool display • 00 (no history)
• 01/03/04 (history exists)
Checking method —
Probable cause of malfunction Check or maintenance job
1 Malfunction in ECU. • Execute the diagnostic mode (Code No. 60).
• Replace ECU if defective.
Reinstatement method Turning the main switch to “ON”.

8-48
 FUEL INJECTION SYSTEM

Fault code No. 46

Item Power supply to the fuel injection system is not normal.
Able to start engine
Fail-safe system
Able to drive vehicle
Diagnostic code No. —
FI diagnostic tool display —
Checking method —
Probable cause of malfunction Check or maintenance job
1 Connections • Check the coupler for any pins that may be
• Wire harness ECU coupler pulled out.
• Check the locking condition of the coupler.
• If there is a malfunction, repair it and connect
the coupler securely.
2 Faulty battery. • Charge or replace the battery.
Refer to “CHECKING AND CHARGING THE
BATTERY” on page 8-78.
3 Malfunction in rectifier/regulator • Replace if defective.
Refer to “CHARGING SYSTEM” on page 8-11.
4 Open or short circuit in wire harness. • Repair or replace if there is an open or short
circuit.
• Between battery terminal and ECU fuse termi-
nal.
(red–red)
• Between ECU fuse terminal and ECU coupler.
(red/green–red/green)
Reinstatement method Starting the engine and operating it at idle.

Fault code No. 50

Faulty ECU memory. (When this malfunction is detected in the
Item
ECU, the fault code number might not appear on the meter.)
Unable to start engine
Fail-safe system
Unable to drive vehicle
Diagnostic code No. —
FI diagnostic tool display —
Checking method —
Probable cause of malfunction Check or maintenance job
1 Malfunction in ECU. • Replace the ECU.
TIP
Do not perform this procedure with the main
switch turned to “ON”.

Reinstatement method Turning the main switch to “ON”.

8-49
 FUEL INJECTION SYSTEM

Fault code No. 61

Item ISC (idle speed control) unit: open or short circuit detected.
Able to start engine
Fail-safe system
Able to drive vehicle
Diagnostic code No. 54
Actuates and fully closes the ISC valve, then opens it to the stand-
by opening position when the engine is started.
Actuation
This operation takes approximately 12 seconds until it is complet-
ed.
Checking method The ISC unit vibrates when the ISC valve operates.
Probable cause of malfunction Check or maintenance job
1 Connections • Check the coupler for any pins that may be
• ISC (idle speed control) unit coupler pulled out.
• Wire harness ECU coupler • Check the locking condition of the coupler.
• If there is a malfunction, repair it and connect
the coupler securely.
2 Open or short circuit in wire harness. • Repair or replace if there is an open or short
circuit.
• Between ISC (idle speed control) unit and
ECU coupler.
(pink–pink)
(light green–light green)
(green–green)
(sky blue–sky blue)
3 Defective ISC (idle speed control) unit. • Execute the diagnostic mode. (Code No. 54)
• Replace if defective.
Refer to “THROTTLE BODY” on page 7-5.
Reinstatement method Turning the main switch to “ON”.

Fault code No. Er-1

ECU internal malfunction (output signal error): no signals are
Item
received from the ECU.
Able/unable to start engine
Fail-safe system
Able/unable to drive vehicle
Diagnostic code No. —
Meter display —
Checking method —
Probable cause of malfunction Check or maintenance job
1 Connections • Check the coupler for any pins that may be
• Meter assembly coupler pulled out.
• Wire harness ECU coupler • Check the locking condition of the coupler.
• Self-diagnosis signal coupler • If there is a malfunction, repair it and connect
the coupler securely.

8-50
 FUEL INJECTION SYSTEM

Fault code No. Er-1

ECU internal malfunction (output signal error): no signals are
Item
received from the ECU.
2 Open or short circuit in wire harness. • Repair or replace if there is an open or short
circuit.
• Between meter assembly coupler and self-di-
agnosis signal coupler.
(yellow/blue–yellow/blue)
• Between self-diagnosis signal coupler and
ECU coupler.
(yellow/blue–yellow/blue)
3 Malfunction in meter assembly. • Replace the meter assembly.
4 Malfunction in ECU. • Replace the ECU.
Reinstatement method Turning the main switch to “ON”.

Fault code No. Er-2

ECU internal malfunction (output signal error): no signals are
Item
received from the ECU within the specified duration.
Able to start engine
Fail-safe system
Able to drive vehicle
Diagnostic code No. —
Meter display —
Checking method —
Probable cause of malfunction Check or maintenance job
1 Connections • Check the coupler for any pins that may be
• Meter assembly coupler pulled out.
• Wire harness ECU coupler • Check the locking condition of the coupler.
• Self-diagnosis signal coupler • If there is a malfunction, repair it and connect
the coupler securely.
2 Open or short circuit in wire harness. • Repair or replace if there is an open or short
circuit.
• Between meter assembly coupler and self-di-
agnosis signal coupler.
(yellow/blue–yellow/blue)
• Between self-diagnosis signal coupler and
ECU coupler.
(yellow/blue–yellow/blue)
3 Malfunction in meter assembly. • Replace the meter assembly.
4 Malfunction in ECU. • Replace the ECU.
Reinstatement method Turning the main switch to “ON”.

8-51
 FUEL INJECTION SYSTEM

Fault code No. Er-3

ECU internal malfunction (output signal error): data from the
Item
ECU cannot be received correctly.
Able to start engine
Fail-safe system
Able to drive vehicle
Diagnostic code No. —
Meter display —
Checking method —
Probable cause of malfunction Check or maintenance job
1 Connections • Check the coupler for any pins that may be
• Meter assembly coupler pulled out.
• Wire harness ECU coupler • Check the locking condition of the coupler.
• Self-diagnosis signal coupler • If there is a malfunction, repair it and connect
the coupler securely.
2 Open or short circuit in wire harness. • Repair or replace if there is an open or short
circuit.
• Between meter assembly coupler and self-di-
agnosis signal coupler.
(yellow/blue–yellow/blue)
• Between self-diagnosis signal coupler and
ECU coupler.
(yellow/blue–yellow/blue)
3 Malfunction in meter assembly. • Replace the meter assembly.
4 Malfunction in ECU. • Replace the ECU.
Reinstatement method Turning the main switch to “ON”.

Fault code No. Er-4

ECU internal malfunction (input signal error): non-registered
Item
data has been received from the meter.
Able to start engine
Fail-safe system
Able to drive vehicle
Diagnostic code No. —
Meter display —
Checking method —
Probable cause of malfunction Check or maintenance job
1 Connections • Check the coupler for any pins that may be
• Meter assembly coupler pulled out.
• Wire harness ECU coupler • Check the locking condition of the coupler.
• Self-diagnosis signal coupler • If there is a malfunction, repair it and connect
the coupler securely.

8-52
 FUEL INJECTION SYSTEM

Fault code No. Er-4

ECU internal malfunction (input signal error): non-registered
Item
data has been received from the meter.
2 Open or short circuit in wire harness. • Repair or replace if there is an open or short
circuit.
• Between meter assembly coupler and self-di-
agnosis signal coupler.
(yellow/blue–yellow/blue)
• Between self-diagnosis signal coupler and
ECU coupler.
(yellow/blue–yellow/blue)
3 Malfunction in meter assembly. • Replace the meter assembly.
4 Malfunction in ECU. • Replace the ECU.
Reinstatement method Turning the main switch to “ON”.

8-53
 FUEL INJECTION SYSTEM

EAS30700

DIAGNOSTIC CODE TABLE

TIP
The following tables contain information about diagnostic code numbers that do not have a correspond-
ing fault code number. (These items are not listed in “TROUBLESHOOTING DETAILS”.)

Diag-
nostic FI diagnostic tool dis-
Item Procedure
code play/Actuation
No.
51 Radiator fan motor relay Actuates the radiator fan mo- Check that the radiator fan
tor relay for five cycles of five motor relay actuates five
seconds. (ON 2 seconds, times by listening for the
OFF 3 seconds) operating sound.
Illuminates the “WARNING”
LED on the FI diagnostic tool
and the engine trouble warn-
ing light and rotates the radi-
ator fan motor.
52 Headlight relay Actuates the headlight relay Check that the headlight re-
for five cycles of five sec- lay actuates five times by
onds. (ON 2 seconds, OFF 3 listening for the operating
seconds) sound.
Illuminates the “WARNING”
LED on the FI diagnostic
tool, the engine trouble warn-
ing light and headlight.
61 Malfunction history code —
display
• No history 00
• History exists Fault codes 12–61
• (If more than one code
number is detected, the dis-
play alternates every two
seconds to show all the de-
tected code numbers.
When all code numbers are
shown, the display repeats
the same process.)
62 Malfunction history code
erasure
• No history 0 —
• History exists Up to 19 fault codes To erase the history, press
the “MODE” button of the
FI diagnostic tool.
70 Control number 0–255 —

8-54
 FUEL INJECTION SYSTEM

Communication error with the FI diagnostic tool

LCD Display Symptom Probable cause of malfunction
• Improper connection in connecting lead.
Waiting for con- No signals are received • The main switch is set to “OFF”.
nection.... from the ECU. • Malfunction in FI diagnostic tool.
• Malfunction in ECU.
• Set the main switch to “OFF” once, and then set
the FI diagnostic tool to the CO adjustment mode
Commands from the FI
or the diagnostic mode.
ERROR 4 diagnostic tool are not
• Vehicle battery is insufficiently charged.
accepted by the ECU.
• Malfunction in FI diagnostic tool.
• Malfunction in ECU.

8-55
 FUEL INJECTION SYSTEM

8-56
 EAS27560
EAS27550

W/R
Gy/B P/W Y/G Br/W L B/W W/R L/Y L/W L/R Sb B/R G B1 W/B
Gy/B W/R R W
2 G/R Y Gy/G Gy/R Gy/B Y/L R/G Gy R/B Lg G/B P B2 O/B O

L/R R/B L/Y G/Y Gy/B

R/B W/Y
W W R L/Y L/R
W W2 W W G/Y R/B (BLUE)
W2 W2 3 G/R Gy/B
W3 W
1 W3 W3 B B
W/R
18 25 32
19 Gy/B R/B
B
B R 17 Gy/R Gy/B Y G/R G/R O O
B R/B L/R 20
W W2 W3 R R A
R (BLACK)
(BLUE) 33 A
Gy/R Gy/R A Gy/R Gy/R
CIRCUIT DIAGRAM

R B
B L/W L/Y
W/Y L/Y 26 Y Y A Y Y L
(BLACK) B Gy/B Gy/R Gy/R Gy/B
Gy/B Gy/B A Gy/B Y
13 (BLUE) Y
12 L/W
L/Y
34
14 O/B R/B R/L O/B WIRE HARNESS SUB-WIRE HARNESS
4 B
L/W
R/L R 21 L/W W/Y Gy/R (BLACK) (BLACK)
B L/W
B Gy/B P/W Gy/R 27 P/W P/W O/B O/B R/B
B Gy/B
R (BLACK)
B B B
22 23 24
FUEL PUMP SYSTEM

16
Gy/B
R 35
Br/W Gy/B L/W 31 Gy/G Gy/G Gy/B
B
28
5 15 (GREEN)
ON Br/W Br/W B/R B/R R/B
Dg Br/W Ch
Br/R Br/R
OFF L/W W/Y G/Y Br B1 B2 R/B B/R
OPEN W L Gy/G Gy/B
Gy/R
R R LOCK Dg Br/W Ch Br G/Y
Ch Br/W Dg Y/G Y/G (BLACK)
Br/L Br/L P Gy/R Y/G Gy/B 29 Gy/B
G/Y Br W/Y L/W

6 B1 P P
Lg Sb
Br/LBr/R R R/G R/G Lg Lg
36 P G
G G
7 Sb Sb (BLACK)
Gy/R
R R/W Gy Gy/B Gy/R O/R B/W P Gy
30 Gy/B Gy
8
Br/R Br/R2
G/B
9 W/B
B/W R/L Br/L R/B R/B
Y/L G/L R/B Y/L
10
R/G B2 B Br/L R/Y
R/W Lg Y/L
11 B2 B/W
Br/L Br

R/B
Br/R2

8-57
B/W
R/Y R/Y2
76 Y/L
Br/W Br
40 R/Y
R/L R/W Br/R2 38
L/B 39
R/B P
R/Y2 W/B (BLACK)

74 L/B W/B
R/W Br/W
G/L Br
L R Br
R/B G/B
41 L/B R/Y Br/W P 37
B
G B
L G/B
B/W R/L
42 43 44 45 46
L
Y/L Y/L

Y/L B B
L Y G P B G/Y
B/W 75 Y/L R 73
R/L Dg Br/W Ch L/B R/Y Br
(BLACK) (BLACK)
G Y Dg Ch B G/Y Br
G Y G/Y B P
B
Ch Br/W Dg Br R/Y L/B

R/B
60 G/L R/L Y/L Br Y Dg Ch

Br
Sb
Gy
61 62 57 B Sb Br B

54 Ch B Ch Dg Dg B 50 Ch Br G/Y 47 Dg Br G/Y
G Y Br

63 64 65 66 67 68 69 70 71 53 52 51 49 48 49
B 55 55 56 56

Sb Ch Br
B/L B G Br Br W
B B
B/L Gy B G/Y
Ch Dg Y R/B R/L Sb Y B G/Y B
G/L Br Y/L B/L Gy B 58 (BLACK)
59 Sb B B Br G B Dg Br B
72 Br Ch
B Gy B B B Y B G/Y
G/Y B
B2 B1 (BLACK)
B B
B1 B1 B/L
FUEL PUMP SYSTEM
 FUEL PUMP SYSTEM

5. Main switch
6. ECU fuse
9. Ignition fuse
12.Battery
13.Main fuse
17.Frame ground
19.Fuel pump
31.ECU (engine control unit)

8-58
 FUEL PUMP SYSTEM

EAS27570

TROUBLESHOOTING
If the fuel pump fails to operate.
TIP
• Before troubleshooting, remove the following part(s):
1. Storage box
2. Front cowling

1. Check the fuses. NG →

(Main, ECU, and ignition)
Replace the fuse(s).
Refer to “CHECKING THE FUS-
ES” on page 8-77.

OK ↓
2. Check the battery. NG →
Refer to “CHECKING AND • Clean the battery terminals.
CHARGING THE BATTERY” on • Recharge or replace the battery.
page 8-78.

OK ↓
3. Check the main switch. NG →
Refer to “CHECKING THE Replace the main switch/immobilizer unit.
SWITCHES” on page 8-73.

OK ↓
4. Check the fuel pump operation. NG →
Refer to “CHECKING THE FUEL Replace the fuel tank (with fuel pump).
PRESSURE” on page 7-3.
OK ↓
5. Check the entire fuel pump system NG →
wiring. Properly connect or repair the fuel pump
Refer to “CIRCUIT DIAGRAM” on system wiring.
page 8-57.

OK ↓
Replace the ECU.

8-59
 FUEL PUMP SYSTEM

8-60
 EAS27650
EAS27640

W/R
Gy/B P/W Y/G Br/W L B/W W/R L/Y L/W L/R Sb B/R G B1 W/B
Gy/B W/R R W
2 G/R Y Gy/G Gy/R Gy/B Y/L R/G Gy R/B Lg G/B P B2 O/B O

L/R R/B L/Y G/Y Gy/B

R/B W/Y
W W R L/Y L/R
W W2 W W G/Y R/B (BLUE)
W2 W2 3 G/R Gy/B
W3 W
1 W3 W3 B B
W/R
18 25 32
19 Gy/B R/B
B
B R 17 Gy/R Gy/B Y G/R G/R O O
B R/B L/R 20
W W2 W3 R R A
R (BLACK)
(BLUE) 33 A
R Gy/R Gy/R A Gy/R Gy/R
B
L/Y
CIRCUIT DIAGRAM

B L/W
W/Y L/Y 26 Y Y A Y Y L
(BLACK) B Gy/B Gy/R Gy/R Gy/B
Gy/B Gy/B A Gy/B Y
13 (BLUE) Y
12 L/W
L/Y
34
14 O/B R/B R/L O/B WIRE HARNESS SUB-WIRE HARNESS
4 B
L/W
R/L R 21 L/W W/Y Gy/R (BLACK) (BLACK)
B L/W
B Gy/B P/W Gy/R 27 P/W P/W O/B O/B R/B
B Gy/B
R (BLACK)
B B B
22 23 24
16
Gy/B
R 35
Br/W Gy/B L/W 31 Gy/G Gy/G Gy/B
B
28
IMMOBILIZER SYSTEM

5 15 (GREEN)
ON Br/W Br/W B/R B/R R/B
Dg Br/W Ch
Br/R Br/R
OFF L/W W/Y G/Y Br B1 B2 R/B B/R
OPEN W L Gy/G Gy/B
Gy/R
R R LOCK Dg Br/W Ch Br G/Y
Ch Br/W Dg Y/G Y/G (BLACK)
Br/L Br/L P Gy/R Y/G Gy/B 29 Gy/B
G/Y Br W/Y L/W

6 B1 P P
Lg Sb
Br/LBr/R R R/G R/G Lg Lg
36 P G
G G
7 Sb Sb (BLACK)
Gy/R
R R/W Gy Gy/B Gy/R O/R B/W P Gy
30 Gy/B Gy
8
Br/R Br/R2
G/B
9 W/B
B/W R/L Br/L R/B R/B
Y/L G/L R/B Y/L
10
R/G B2 B Br/L R/Y
R/W Lg Y/L
11 B2 B/W
Br/L Br

R/B
B/W Br/R2
R/Y R/Y2
Y/L

8-61
76 Br
Br/W
40 R/Y
R/L R/W Br/R2 38
L/B 39
R/B P
R/Y2 W/B (BLACK)

74 L/B W/B
R/W Br/W
G/L Br
L R Br
R/B G/B
41 L/B R/Y Br/W P 37
B
G B
L G/B
B/W R/L
42 43 44 45 46
L
Y/L Y/L

Y/L B B
L Y G P B G/Y
B/W 75 Y/L R 73
R/L Dg Br/W Ch L/B R/Y Br
(BLACK) (BLACK)
G Y Dg Ch B G/Y Br
G Y G/Y B P
B
Ch Br/W Dg Br R/Y L/B

R/B
60 G/L R/L Y/L Br Y Dg Ch

Br
Sb
Gy
61 62 57 B Sb Br B

54 Ch B Ch Dg Dg B 50 Ch Br G/Y 47 Dg Br G/Y
G Y Br

63 64 65 66 67 68 69 70 71 53 52 51 49 48 49
B 55 55 56 56

Sb Ch Br
B/L B G Br Br W
B B
B/L Gy B G/Y
Ch Dg Y R/B R/L Sb Y B G/Y B
G/L Br Y/L B/L Gy B 58 (BLACK)
59 Sb B B Br G B Dg Br B
72 Br Ch
B Gy B B B Y B G/Y
G/Y B
B2 B1 (BLACK)
B B
B1 B1 B/L
IMMOBILIZER SYSTEM
 IMMOBILIZER SYSTEM

4. Backup fuse (immobilizer unit and meter

assembly)
5. Main switch
6. ECU fuse
9. Ignition fuse
12.Battery
13.Main fuse
17.Frame ground
31.ECU (engine control unit)
61.Immobilizer system indicator light
62.Multifunction meter
75.Self-diagnosis signal coupler
76.Immobilizer unit

8-62
 IMMOBILIZER SYSTEM

EAS27670

GENERAL INFORMATION
This vehicle is equipped with an immobilizer system to help prevent theft by re-registering codes in the
standard keys. This system consists of the following:
• a code re-registering key (with a red bow)
• two standard keys (with a black bow) that can be re-registered with new codes
• a transponder (installed in the red key bow)
• an immobilizer unit
• the ECU
• an immobilizer system indicator light
The key with the red bow is used to register codes in each standard key. Do not use the key with the
red bow for driving. It should only be used for re-registering new codes in the standard keys. The im-
mobilizer system cannot be operated with a new key until the key is registered with a code. If you lose
the code re-registering key, the ECU and main switch (equipped with the immobilizer unit) need to be
replaced.
Therefore, always use a standard key for driving. (See NOTICE.)
TIP
Each standard key is registered during production, therefore re-registering at purchase is not neces-
sary.
ECA37P1038

NOTICE
• DO NOT LOSE THE CODE RE-REGISTERING KEY! If the code re-registering key is lost, regis-
tering new codes in the standard keys is impossible. The standard keys can still be used to
start the vehicle. However, if code re-registering is required (e.g., if a new standard key is made
or all keys are lost) the entire immobilizer system must be replaced. Therefore, it is highly rec-
ommended to use either standard key for driving, and to keep the code re-registering key in a
safe place.
• Do not submerse the keys in water.
• Do not expose the keys to excessively high temperatures.
• Do not place the keys close to magnets (this includes, but is not limited to, products such as
speakers, etc.).
• Do not place heavy items on the keys.
• Do not grind the keys or alter their shape.
• Do not disassemble the key bows.
• Do not put two keys of any immobilizer system on the same key ring.
• Keep the standard keys as well as other immobilizer system keys away from the code re-reg-
istering key.
• Keep other immobilizer system keys away from the main switch as they may cause signal in-
terference.

EAS27690

PART REPLACEMENT AND KEY CODE REGISTRATION REQUIREMENTS

In the course of use, you may encounter the following cases where replacement of parts and registra-
tion of code re-registering/standard keys are required.
TIP
Each standard key is registered during production, therefore re-registering at purchase is not neces-
sary.

8-63
 IMMOBILIZER SYSTEM

Parts to be replaced
Main switch/immo-
bilizer unit Accesso- Key registration re-
Standard quirement
ECU ry lock*
Main Immobiliz- key
and key
switch er unit
Standard key is lost √ New standard key
All keys have been Code re-registering
lost (including code √ √ √ √ key and standard
re-registering key) keys
Code re-registering
ECU is defective √ key and standard
keys
Code re-registering
Immobilizer unit is
√ key and standard
defective
keys
Code re-registering
Main switch is defec-
√ √ √ √ key and standard
tive
keys
Accessory lock* is
√ Not required
defective

* Accessory locks mean the seat lock and fuel tank cap.

Code re-registering key registration:

When the immobilizer unit or ECU is replaced, the code re-registering key must be registered to the
unit.
To register a code re-registering key:
1. Turn the main switch to “ON” with the code re-registering key.
TIP
Check that the immobilizer system indicator light comes on for one second, then goes off. When the
immobilizer system indicator light goes off, the code re-registering key has been registered.
2. Check that the engine can be started.
3. Register the standard key, following the instructions in the section below.

Standby mode:
To enable the immobilizer system, turn the ignition key to “OFF”. 30 seconds later, the indicator light
will start flashing continuously in the standby flashing mode pattern for up to 24 hours. After that time,
the indicator light will stop flashing, but the immobilizer system is still enabled.

8-64
 IMMOBILIZER SYSTEM

Standby mode

a. Main switch “ON” e. Standby mode on

b. Main switch “OFF” f. Standby mode off
c. LED on
d. LED off

Standard key registration:

Standard key registration is required when a standard key is lost and needs to be replaced, or when
the code re-registering key is re-registered after the immobilizer unit or ECU are replaced.
TIP
Do not start the engine with a standard key that has not been registered. If the main switch is turned
“ON” with a standard key that has not been registered, the immobilizer system indicator light flashes to
indicate fault code “52”. (Refer to “SELF-DIAGNOSIS FAULT CODE INDICATION” on page 8-67.)
1. Check that the immobilizer system indicator light signals the standby mode.
2. Using the code re-registering key, turn the main switch to “ON”, then “OFF”, and then remove the
key within 5 seconds.
3. Insert the first standard key to be registered into the main switch, then turn the key to “ON” within 5
seconds to activate the key registration mode.
TIP
The existing standard key code is erased from the memory when the key registration mode is activated.
When the key registration mode is activated, the immobilizer system indicator light flashes rapidly.
4. While the indicator light is flashing, turn the main switch to “OFF”, remove the key, and within 5 sec-
onds, insert the second standard key to be registered into the main switch.
TIP
If the immobilizer system indicator light stops flashing 5 seconds after the first standard key is regis-
tered, the registration mode is deactivated. If this occurs, the second standard key cannot be registered,
and steps 2 to 4 need to be repeated to register both standard keys.
5. Turn the main switch to “ON”.
TIP
When the indicator light goes off, the registration is complete.
6. Check that the engine can be started with the two registered standard keys.

8-65
 IMMOBILIZER SYSTEM

Standard key registration

a. Main switch “ON” B. Immobilizer system indicator light stops

b. Main switch “OFF” flashing when the registration of the second
standard key is complete.
c. LED on
d. LED off
e. Less than 5.0 s
f. Code re-registering key
g. First standard key
h. Second standard key
i. Registration mode
A. Registration of the second standard key is
complete.

Voiding the standard key code:

If a standard key has been lost, it is possible to disable its use by re-registering the remaining standard
key. Standard key registration erases the stored standard key code from the memory, thus disabling
the lost standard key. To re-register, refer to “Standard key registration”.
Standard key code voiding method

a. Main switch “ON”

b. Main switch “OFF”
c. LED on
d. LED off
e. Less than 5.0 s
f. Code re-registering key
g. Remaining standard key
h. Registration mode
A. If the immobilizer system indicator light stops
flashing 5 seconds after the first standard key
is registered, the second standard key cannot
be registered.

8-66
 IMMOBILIZER SYSTEM

EAS27700

TROUBLESHOOTING
When the main switch is turned to “ON”, the immobilizer system indicator light does not come on nor
flashes.
1. Check the fuses. NG →
(Main, ignition, ECU, and backup)
Replace the fuse(s).
Refer to “CHECKING THE FUS-
ES” on page 8-77.
OK ↓
2. Check the battery. NG →
Refer to “CHECKING AND • Clean the battery terminals.
CHARGING THE BATTERY” on • Recharge or replace the battery.
page 8-78.

OK ↓
3. Check the main switch. NG →
Refer to “CHECKING THE Replace the main switch/immobilizer unit.
SWITCHES” on page 8-73.

OK ↓
NG →
4. Check the entire immobilizer sys-
tem wiring. Properly connect or repair the immobilizer
Refer to “CIRCUIT DIAGRAM” on system wiring.
page 8-61.

OK ↓
• Check the condition each of the im-
mobilizer system circuits.
• Refer to “SELF-DIAGNOSIS FAULT
CODE INDICATION” on page 8-67.

EAS27720

SELF-DIAGNOSIS FAULT CODE INDICATION

When a system malfunction occurs, the fault code number is indicated in the LCD display of the meter
assembly and the immobilizer system indicator light flashes at the same time. The pattern of flashing
also shows the fault code.
Fault
Part Symptom Cause Action
code
51 IMMOBILIZER Code cannot be 1. Radio wave interfer- 1. Keep magnets,
UNIT transmitted be- ence caused by ob- metal objects,
tween the key and jects around the keys and other immo-
the immobilizer unit. and antenna. bilizer system
2. Immobilizer unit mal- keys away from
function. the keys and an-
3. Key malfunction. tennas.
2. Replace the
main switch/im-
mobilizer unit.
3. Replace the key.

8-67
 IMMOBILIZER SYSTEM

Fault
Part Symptom Cause Action
code
52 IMMOBILIZER Codes between the 1. Signal received from 1. Place the immo-
UNIT key and immobilizer other transponder bilizer unit at
unit do not match. (failed to recognize least 50 mm
code after ten con- away from the
secutive attempts). transponder of
2. Signal received from other vehicles.
unregistered stan- 2. Register the
dard key. standard key.
53 IMMOBILIZER Codes cannot be Noise interference or 1. Check the wire
UNIT transmitted be- disconnected lead/ca- harness and
tween the ECU and ble. connector.
the immobilizer unit. 1. Interference due to 2. Replace the
radio wave noise. main switch/im-
2. Disconnected com- mobilizer unit.
munication harness. 3. Replace the
3. Immobilizer unit mal- ECU.
function.
4. ECU malfunction.
54 IMMOBILIZER Codes transmitted Noise interference or 1. Register the
UNIT between the ECU disconnected lead/ca- code re-register-
and the immobilizer ble. ing key.
unit do not match. 1. Interference due to 2. Check the wire
radio wave noise. harness and
2. Disconnected com- connector.
munication harness. 3. Replace the
3. Immobilizer unit mal- main switch/im-
function. mobilizer unit.
4. ECU failure. 4. Replace the
(The ECU or immobi- ECU.
lizer unit was re-
placed with a used
unit from another ve-
hicle.)
55 IMMOBILIZER Key code registra- Same standard key was
UNIT tion malfunction. attempted to be regis- Register another
tered two consecutive standard key.
times.
56 ECU Unidentified code is Noise interference or 1. Check the wire
received. disconnected lead/ca- harness and
ble. connector.
2. Replace the
main switch/im-
mobilizer unit.
3. Replace the
ECU.

Immobilizer system indicator light fault code indication

Units of 10: Cycles of on for 1 second and off for 1.5 seconds.
Units of 1: Cycles of on for 0.5 second and off for 0.5 second.
Example: fault code 52

8-68
 IMMOBILIZER SYSTEM

a. Light on
b. Light off

8-69
 IMMOBILIZER SYSTEM

8-70
 ELECTRICAL COMPONENTS

EAS27970

ELECTRICAL COMPONENTS

4 5 6
3 7
2
8
1

30
9

10
29
11
12
13
28

14
27

15

26 16

25
17
24

18
23
22 19
21 20

8-71
 ELECTRICAL COMPONENTS

1. Battery
2. Air temperature sensor
3. ECU (engine control unit)
4. Front brake light switch
5. Rear brake light switch
6. Main switch/immobilizer unit
7. Fuel sender
8. Ignition coil
9. Fuel injector
10. Intake air temperature sensor
11. Intake air pressure sensor
12. Throttle position sensor
13. ISC (idle speed control) unit
14. Crankshaft position sensor
15. Stator coil
16. Coolant temperature sensor
17. O2 sensor
18. Sidestand switch
19. Starter relay
20. Main fuse
21. Headlight relay
22. Radiator fan motor
23. Horn
24. Starting circuit cut-off relay
25. Speed sensor
26. Rectifier/regulator
27. Radiator fan motor relay
28. Diode
29. Lean angle sensor
30. Turn signal relay

8-72
 ELECTRICAL COMPONENTS

EAS27980

CHECKING THE SWITCHES

1 2 3 4
L/W W/Y Dg Br/W Ch R Br/L Br/R Br/R
ON
OFF
OPEN R
LOCK
Br/L
P
Dg Br/W Ch
L/W W/Y G/Y Br
Br G/Y

5 7 9 10
L/B G Y Dg Br/W Ch

B
B
6 8
(BLUE)
R/Y Y P B

G/Y Br

Y G P B G/Y
Dg Br/W Ch L/B R/Y Br

8-73
 ELECTRICAL COMPONENTS

1. Start switch
2. Hazard switch
3. Front brake light switch
4. Main switch
5. Dimmer switch
6. Pass switch
7. Turn signal switch
8. Horn switch
9. Rear brake light switch
10. Sidestand switch

8-74
 ELECTRICAL COMPONENTS

Check each switch for continuity with the pocket tester. If the continuity reading is incorrect, check the
wiring connections and, if necessary, replace the switch.
ECA14370

NOTICE
Never insert the tester probes into the coupler terminal slots “a”. Always insert the probes from
the opposite end of the coupler, taking care not to loosen or damage the leads.

Pocket tester
90890-03112
Analog pocket tester
YU-03112-C

TIP
• Before checking for continuity, set the pocket tester to “0” and to the “Ω × 1” range.
• When checking for continuity, switch back and forth between the switch positions a few times.

The switches and their terminal connections are illustrated as in the following example of the main
switch.
The switch positions “a” are shown in the far left column and the switch lead colors “b” are shown in the
top row.
The continuity (i.e., a closed circuit) between switch terminals at a given switch position is indicated by
“ ”. There is continuity between red, brown/blue, and brown/red when the switch is set to “ON”.
b
R Br/L Br/R
ON
OFF
a OPEN
LOCK
P

R
Br/R
Br/L

8-75
 ELECTRICAL COMPONENTS

EAS27990 EWA37P1018

CHECKING THE BULBS AND BULB WARNING

SOCKETS Since headlight bulbs get extremely hot,
TIP keep flammable products and your hands
Do not check any of the lights that use LEDs. away from them until they have cooled
down.
Check each bulb and bulb socket for damage or
ECA37P1039
wear, proper connections, and also for continuity
NOTICE
between the terminals.
Damage/wear → Repair or replace the bulb, • Be sure to hold the socket firmly when re-
bulb socket or both. moving the bulb. Never pull the lead, other-
Improperly connected → Properly connect. wise it may be pulled out of the terminal in
No continuity → Repair or replace the bulb, bulb the coupler.
socket or both. • Avoid touching the glass part of a headlight
bulb to keep it free from oil, otherwise the
Types of bulbs transparency of the glass, the life of the
The bulbs used on this vehicle are shown in the bulb, and the luminous flux will be adverse-
illustration. ly affected. If the headlight bulb gets soiled,
• Bulbs “a” and “b” are used for the headlights thoroughly clean it with a cloth moistened
and usually use a bulb holder that must be de- with alcohol or lacquer thinner.
tached before removing the bulb. The majority 2. Check:
of these types of bulbs can be removed from • Bulb (for continuity)
their respective socket by turning them coun- (with the pocket tester)
terclockwise. No continuity → Replace.
• Bulbs “c” are used for turn signal and tail/brake
lights and can be removed from the socket by Pocket tester
pushing and turning the bulb counterclockwise. 90890-03112
Analog pocket tester
YU-03112-C

TIP
Before checking for continuity, set the pocket
tester to “0” and to the “Ω × 1” range.
▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼
a. Connect the positive tester probe to terminal
“1” and the negative tester probe to terminal
“2”, and check the continuity.
b. Connect the positive tester probe to terminal
“1” and the negative tester probe to terminal
“3”, and check the continuity.
c. If either of the readings indicate no continuity,
replace the bulb.
▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲

Checking the condition of the bulbs

The following procedure applies to all of the
bulbs.
1. Remove:
• Bulb

8-76
 ELECTRICAL COMPONENTS

Checking the condition of the bulb sockets Amperage

The following procedure applies to all of the bulb Fuses Q’ty
rating
sockets.
1. Check: Backup (immobilizer
5.0 A 1
• Bulb socket (for continuity) and meter assembly)
(with the pocket tester) Spare 30.0 A 1
No continuity → Replace. Spare 15.0 A 1
Pocket tester Spare 10.0 A 1
90890-03112 Spare 7.5 A 1
Analog pocket tester
YU-03112-C Spare 5.0 A 1

TIP
Check each bulb socket for continuity in the
same manner as described in the bulb section,
however, note the following.
▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼
a. Install a good bulb into the bulb socket.
b. Connect the pocket tester probes to the re-
spective leads of the bulb socket.
c. Check the bulb socket for continuity. If any of
the readings indicate no continuity, replace
the bulb socket.
▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲
EAS28000

CHECKING THE FUSES

The fuse box, which contains the fuses for the in-
dividual circuits, is located behind the upper
panel. The main fuse and spare fuse (30.0 A)
are located behind the front cowling assembly.
ECA37P1040

NOTICE ▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼
To avoid a short circuit, always set the main a. Connect the pocket tester to the fuse and
switch to “OFF” when checking or replacing check the continuity.
a fuse. TIP
1. Remove: Set the pocket tester selector to “Ω × 1”.
• Upper panel and/or front cowling assembly
Refer to “GENERAL CHASSIS” on page 4-1. Pocket tester
2. Check: 90890-03112
• Fuse Analog pocket tester
YU-03112-C
Amperage
Fuses Q’ty
rating b. If the pocket tester indicates “∞”, replace the
Main 30.0 A 1 fuse.
Headlight 15.0 A 1 ▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲
3. Replace:
Signaling system 10.0 A 1
• Blown fuse
Ignition 10.0 A 1 ▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼
Turn signal/hazard 10.0 A 1 a. Set the main switch to “OFF”.
b. Install a new fuse of the correct amperage
Radiator fan motor 7.5 A 1 rating.
ECU 5.0 A 1

8-77
 ELECTRICAL COMPONENTS

c. Set on the switches to verify if the electrical ECA13661

circuit is operational. NOTICE

d. If the fuse immediately blows again, check • This is a VRLA (Valve Regulated Lead Acid)
the electrical circuit. battery. Never remove the sealing caps be-
EWA13310 cause the balance between cells will not be
WARNING maintained and battery performance will
Never use a fuse with an amperage rating deteriorate.
other than that specified. Improvising or us- • Charging time, charging amperage and
ing a fuse with the wrong amperage rating charging voltage for a VRLA (Valve Regu-
may cause extensive damage to the electri- lated Lead Acid) battery are different from
cal system, cause the lighting and ignition those of conventional batteries. The VRLA
systems to malfunction and could possibly (Valve Regulated Lead Acid) battery should
cause a fire. be charged according to the appropriate
charging method. If the battery is over-
▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲
charged, the electrolyte level will drop con-
4. Install: siderably. Therefore, take special care
• Upper panel and/or front cowling assembly when charging the battery.
Refer to “GENERAL CHASSIS” on page 4-1.
TIP
EAS28030

CHECKING AND CHARGING THE BATTERY Since VRLA (Valve Regulated Lead Acid) bat-
EWA13290 teries are sealed, it is not possible to check the
WARNING charge state of the battery by measuring the
Batteries generate explosive hydrogen gas specific gravity of the electrolyte. Therefore, the
and contain electrolyte which is made of poi- charge of the battery has to be checked by mea-
sonous and highly caustic sulfuric acid. suring the voltage at the battery terminals.
Therefore, always follow these preventive 1. Remove:
measures: • Upper panel
• Wear protective eye gear when handling or Refer to “GENERAL CHASSIS” on page 4-1.
working near batteries. 2. Disconnect:
• Charge batteries in a well-ventilated area. • Battery leads
• Keep batteries away from fire, sparks or (from the battery terminals)
open flames (e.g., welding equipment, ECA13640

lighted cigarettes). NOTICE

• DO NOT SMOKE when charging or han- First, disconnect the negative battery lead
dling batteries. “1”, and then the positive battery lead “2”.
• KEEP BATTERIES AND ELECTROLYTE
OUT OF REACH OF CHILDREN.
2 1
• Avoid bodily contact with electrolyte as it
can cause severe burns or permanent eye
injury.
FIRST AID IN CASE OF BODILY CONTACT:
EXTERNAL
• Skin — Wash with water.
• Eyes — Flush with water for 15 minutes and
get immediate medical attention.
INTERNAL
• Drink large quantities of water or milk fol- 3. Remove:
lowed with milk of magnesia, beaten egg or • Battery
vegetable oil. Get immediate medical atten- 4. Check:
tion. • Battery charge
▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼
a. Connect a pocket tester to the battery termi-
nals.

8-78
 ELECTRICAL COMPONENTS

• Positive tester probe → 5. Charge:

positive battery terminal • Battery
• Negative tester probe → (refer to the appropriate charging method)
negative battery terminal EWA13300

WARNING
TIP Do not quick charge a battery.
• The charge state of a VRLA (Valve Regulated ECA13671

Lead Acid) battery can be checked by measur- NOTICE

ing its open-circuit voltage (i.e., the voltage • Do not use a high-rate battery charger
when the positive battery terminal is discon- since it forces a high-amperage current
nected). into the battery quickly and can cause bat-
• No charging is necessary when the open-cir- tery overheating and battery plate damage.
cuit voltage equals or exceeds 12.8 V. • If it is impossible to regulate the charging
b. Check the charge of the battery, as shown in current on the battery charger, be careful
the charts and the following example. not to overcharge the battery.
• When charging a battery, be sure to remove
Example
it from the vehicle. (If charging has to be
Open-circuit voltage = 12.0 V
Charging time = 6.5 hours done with the battery mounted on the vehi-
Charge of the battery = 20–30% cle, disconnect the negative battery lead
from the battery terminal.)
• To reduce the chance of sparks, do not
plug in the battery charger until the battery
charger leads are connected to the battery.
• Before removing the battery charger lead
clips from the battery terminals, be sure to
turn off the battery charger.
• Make sure the battery charger lead clips are
in full contact with the battery terminal and
that they are not shorted. A corroded bat-
tery charger lead clip may generate heat in
A. Open-circuit voltage (V) the contact area and a weak clip spring may
B. Charging time (hours) cause sparks.
C. Relationship between the open-circuit voltage • If the battery becomes hot to the touch at
and the charging time at 20 °C (68 °F) any time during the charging process, dis-
D. These values vary with the temperature, the connect the battery charger and let the bat-
condition of the battery plates, and the tery cool before reconnecting it. Hot
electrolyte level.
batteries can explode!
• As shown in the following illustration, the
open-circuit voltage of a VRLA (Valve Reg-
ulated Lead Acid) battery stabilizes about
30 minutes after charging has been com-
pleted. Therefore, wait 30 minutes after
charging is completed before measuring
the open-circuit voltage.

A. Open-circuit voltage (V)

B. Charging condition of the battery (%)
C. Ambient temperature 20 °C (68 °F)

▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲

8-79
 ELECTRICAL COMPONENTS

7. Connect:
• Battery leads
(to the battery terminals)
ECA13630

NOTICE
First, connect the positive battery lead “1”,
and then the negative battery lead “2”.

1 2

A. Open-circuit voltage (V)

B. Time (minutes)
C. Charging
D. Ambient temperature 20 °C (68 °F)
E. Check the open-circuit voltage.

▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼
Charging method using a constant volt-
8. Check:
age charger
• Battery terminals
a. Measure the open-circuit voltage prior to
Dirt → Clean with a wire brush.
charging.
Loose connection → Connect properly.
TIP 9. Install:
Voltage should be measured 30 minutes after • Upper panel
the engine is turned off. Refer to “GENERAL CHASSIS” on page 4-1.
b. Connect a charger and ammeter to the bat- EAS28040

tery and start charging. CHECKING THE RELAYS

c. Make sure that the current is higher than the Check each switch for continuity with the pocket
standard charging current written on the bat- tester. If the continuity reading is incorrect, re-
tery. place the relay.
TIP
Pocket tester
If the current is lower than the standard charging 90890-03112
current written on the battery, this type of battery Analog pocket tester
charger cannot charge the VRLA (Valve Regu- YU-03112-C
lated Lead Acid) battery. A variable voltage
charger is recommended. 1. Disconnect the relay from the wire harness.
d. Charge the battery until the battery’s charg- 2. Connect the pocket tester (Ω × 1) and battery
ing voltage is 15 V. (12 V) to the relay terminal as shown.
Check the relay operation.
TIP
Out of specification → Replace.
Set the charging time at 20 hours (maximum).
e. Measure the battery open-circuit voltage after
leaving the battery unused for more than 30
minutes.
12.8 V or more --- Charging is complete.
12.7 V or less --- Recharging is required.
Under 12.0 V --- Replace the battery.

▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲
6. Install:
• Battery

8-80
 ELECTRICAL COMPONENTS

Starting circuit cut-off relay 2. Negative battery terminal

3. Positive tester probe
4 4. Negative tester probe
1

Result
Continuity
+ 2 3 (between “3” and “4”)
L/Y G/Y
R/B W/Y Radiator fan motor relay
3
1. Positive battery terminal 4 +
2. Negative battery terminal
3. Positive tester probe 2
1
4. Negative tester probe
G/B R/B
Result L
Continuity R/W
(between “3” and “4”)
1. Positive battery terminal
Starter relay 2. Negative battery terminal
3. Positive tester probe
3
4. Negative tester probe
R
Result
R Continuity
B L/W (between “3” and “4”)
R
1 2 EAS37P1082

CHECKING THE TURN SIGNAL/HAZARD

4 RELAY
1. Positive battery terminal
1. Check:
2. Negative battery terminal
• Turn signal/hazard relay input voltage
3. Positive tester probe
Out of specification → The wiring circuit from
4. Negative tester probe
the main switch to the turn signal/hazard re-
lay coupler is faulty and must be repaired.

Result Turn signal/hazard relay input

Continuity voltage
(between “3” and “4”) DC 12 V

▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼
Headlight relay a. Connect the pocket tester (DC 20 V) to the
turn signal/hazard relay terminal as shown.
3
4 + Pocket tester
90890-03112
2 Analog pocket tester
1 YU-03112-C
W/B R/Y
L/B • Positive tester probe →
R/Y brown/red “1”
• Negative tester probe →
ground
1. Positive battery terminal

8-81
 ELECTRICAL COMPONENTS

EAS28060

CHECKING THE SPARK PLUG CAP

1. Check:
• Spark plug cap resistance
Out of specification → Replace.

Resistance
Br/R 10.0 kΩ

▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼
a. Remove the spark plug cap from the spark
b. Set the main switch to “ON”. plug lead.
c. Measure the turn signal/hazard relay input b. Connect the pocket tester (Ω × 1k) to the
voltage. spark plug cap as shown.
▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲
Pocket tester
2. Check: 90890-03112
• Turn signal/hazard relay output voltage Analog pocket tester
Out of specification → Replace. YU-03112-C
Turn signal/hazard relay output
voltage
DC 12 V

▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼
a. Connect the pocket tester (DC 20 V) to the
turn signal/hazard relay terminal as shown.

Pocket tester
90890-03112
Analog pocket tester
YU-03112-C c. Measure the spark plug cap resistance.
▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲
• Positive tester probe → EAS28090
brown/white “1” CHECKING THE IGNITION COIL
• Negative tester probe → 1. Check:
ground
• Primary coil resistance
Out of specification → Replace.

Primary coil resistance

2.16–2.64 Ω at 20 °C (68 °F)

▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼
a. Disconnect the ignition coil connectors from
Br/R the ignition coil terminals.
b. Connect the pocket tester (Ω × 1) to the igni-
tion coil as shown.

b. Set the main switch to “ON”. Pocket tester

c. Measure the turn signal/hazard relay output 90890-03112
voltage. Analog pocket tester
YU-03112-C
▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲

• Positive tester probe →

red/black “1”
• Negative tester probe →
orange “2”

8-82
 ELECTRICAL COMPONENTS

Refer to “TROUBLESHOOTING” on page

8-3.

Minimum ignition spark gap

6.0 mm (0.24 in)

TIP
If the ignition spark gap is within specification,
the ignition system circuit is operating normally.
▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼
c. Measure the primary coil resistance. a. Disconnect the spark plug cap from the spark
▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲ plug.
2. Check: b. Connect the ignition checker “1” as shown.
• Secondary coil resistance
Out of specification → Replace. Ignition checker
90890-06754
Secondary coil resistance Oppama pet-4000 spark checker
8.64–12.96 kΩ at 20 °C (68 °F) YM-34487

▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼
a. Disconnect the spark plug cap from the igni-
tion coil.
b. Connect the pocket tester (Ω × 1k) to the ig-
nition coil as shown.

Pocket tester
90890-03112
Analog pocket tester
YU-03112-C
2. Spark plug cap
• Positive tester probe →
red/black “1” c. Set the main switch to “ON”.
• Negative tester probe → d. Measure the ignition spark gap “a”.
Spark plug lead “2” e. Crank the engine by pushing the start switch
“ ” and gradually increase the spark gap un-
til a misfire occurs.
▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲
EAS28120

CHECKING THE CRANKSHAFT POSITION

SENSOR
1. Disconnect:
• Crankshaft position sensor coupler
(from the wire harness)
2. Check:
c. Measure the secondary coil resistance. • Crankshaft position sensor resistance
Out of specification → Replace the crank-
▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲
shaft position sensor/stator assembly.
EAS28930

CHECKING THE IGNITION SPARK GAP Crankshaft position sensor resis-

1. Check: tance
• Ignition spark gap 248–372 Ω at 20 °C (68 °F)
Out of specification → Perform the ignition
system troubleshooting, starting with step 5. ▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼
a. Connect the pocket tester (Ω × 100) to the
crankshaft position sensor coupler as shown.

8-83
 ELECTRICAL COMPONENTS

Pocket tester
90890-03112 45˚
45˚
Analog pocket tester
YU-03112-C

• Positive tester probe →

red “1” Gy/R Y/G Gy/B
• Negative tester probe →
white “2” 1 2

c. Set the main switch to “ON”.

d. Turn the lean angle sensor 45°.
e. Measure the lean angle sensor output volt-
age.
▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲
EAS28940

CHECKING THE STARTER MOTOR

R W
OPERATION
1 2 1. Check:
• Starter motor operation
b. Measure the crankshaft position sensor re- Does not operate → Perform the electric
sistance. starting system troubleshooting, starting with
▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲ step 4.
EAS28130
Refer to “TROUBLESHOOTING” on page
CHECKING THE LEAN ANGLE SENSOR 8-9.
1. Remove: ▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼
• Lean angle sensor a. Connect the positive battery terminal “1” and
2. Check: starter motor lead “2” with a jumper lead “3”.
EWA13810
• Lean angle sensor output voltage WARNING
Out of specification → Replace.
• A wire that is used as a jumper lead must
Lean angle sensor output voltage have at least the same capacity of the bat-
Less than 45°: 0.4–1.4 V tery lead, otherwise the jumper lead may
More than 45°: 3.7–4.4 V burn.
• This check is likely to produce sparks,
▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼ therefore, make sure no flammable gas or
a. Connect the test harness-lean angle sensor fluid is in the vicinity.
(6P) between the lean angle sensor and wire
harness.
b. Connect the pocket tester (DC 20 V) to the
test harness-lean angle sensor (6P).

Test harness-lean angle sensor

(6P)
90890-03209
Pocket tester
90890-03112
Analog pocket tester
YU-03112-C
b. Check the starter motor operation.
▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲
• Positive tester probe →
yellow/green “1”
• Negative tester probe →
gray/black “2”

8-84
 ELECTRICAL COMPONENTS

EAS28150 EAS28170

CHECKING THE STATOR COIL CHECKING THE RECTIFIER/REGULATOR

1. Disconnect: 1. Check:
• Stator coil coupler • Charging voltage
(from the wire harness) Out of specification → Replace the rectifi-
2. Check: er/regulator.
• Stator coil resistance
Out of specification → Replace the crank- Charging voltage
shaft position sensor/stator assembly. 14 V at 5000 r/min

Stator coil resistance ▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼

0.28–0.42 Ω at 20 °C (68 °F) a. Connect the engine tachometer to the spark
(YP125R) plug lead.
0.32–0.48 Ω at 20 °C (68 °F) b. Connect the pocket tester (DC 20 V) to the
(YP250R) battery as shown.

▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼ Pocket tester

a. Connect the pocket tester (Ω × 1) to the stator 90890-03112
coil coupler as shown. Analog pocket tester
YU-03112-C
Pocket tester
90890-03112 • Positive tester probe →
Analog pocket tester positive battery terminal “1”
YU-03112-C • Negative tester probe →
negative battery terminal “2”
• Positive tester probe →
white “1”
• Negative tester probe →
white “2”

• Positive tester probe →

white “1”
• Negative tester probe →
white “3”

• Positive tester probe →

white “2” c. Start the engine and let it run at approximate-
• Negative tester probe →
ly 5000 r/min.
white “3”
d. Measure the charging voltage.
▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲
EAS28180

CHECKING THE HORN

1. Check:
• Horn resistance
Out of specification → Replace.
1 3
W W
Coil resistance
2
W 1.4 Ω at 20 °C (68 °F)

▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼
b. Measure the stator coil resistance. a. Disconnect the horn connectors from the
▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲ horn terminals.
b. Connect the pocket tester (Ω × 1) to the horn
terminals.

8-85
 ELECTRICAL COMPONENTS

Pocket tester
90890-03112
Analog pocket tester
A
YU-03112-C
B
• Positive tester probe →
horn terminal “1”
• Negative tester probe →
horn terminal “2”
1

Sb
1 B

2
2

c. Measure the horn resistance.

▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲ A. Full fuel tank position
EAS28230
B. Empty fuel tank position
CHECKING THE FUEL SENDER
b. Measure the fuel sender resistance.
1. Remove:
▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲
• Fuel sender
2. Check: EAS29040

CHECKING THE FUEL LEVEL WARNING

• Fuel sender resistance
LIGHT
Out of specification → Replace the fuel send-
This model is equipped with a self-diagnosis de-
er.
vice for the fuel level detection circuit.
Sender unit resistance (full) 1. Check:
20.0 Ω • Fuel level warning light “1”
Sender unit resistance (empty) (Set the main switch to “ON”.)
140.0 Ω The warning light comes on for a few sec-
onds, then goes off → The warning light is
▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼ OK.
a. Connect the pocket tester (Ω × 10) to the fuel The warning light does not come on → Re-
sender terminal as shown. place the meter assembly.
Pocket tester All LCD segments of the fuel meter “2” and
90890-03112 the fuel level warning light “1” flash (open or
Analog pocket tester short circuit detected in fuel sender) → Re-
YU-03112-C place the fuel sender.
21
• Positive tester probe →
sky blue “1”
• Negative tester probe →
black “2”

8-86
 ELECTRICAL COMPONENTS

EAS28240

CHECKING THE SPEED SENSOR

1. Check:
• Speed sensor output voltage
Out of specification → Replace.

Output voltage reading cycle

0.6 V to 4.8 V to 0.6 V to 4.8 V

▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼
a. Connect the pocket tester (DC 20 V) to the
speed sensor coupler (wire harness end) as c. Measure the radiator fan motor movement.
shown. ▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲
EAS28260
Pocket tester
CHECKING THE COOLANT TEMPERATURE
90890-03112
Analog pocket tester SENSOR
YU-03112-C 1. Remove:
• Coolant temperature sensor
• Positive tester probe → Refer to “CYLINDER HEAD (YP125R)” on
gray “1” page 5-7 and “CYLINDER HEAD (YP250R)”
• Negative tester probe → on page 5-67.
EWA14130
gray/black “2”
WARNING
• Handle the coolant temperature sensor
with special care.
• Never subject the coolant temperature sen-
1
sor to strong shocks. If the coolant temper-
Gy P ature sensor is dropped, replace it.
Gy/B B/W
2. Check:
Gy/R O/R
2 • Coolant temperature sensor resistance
Out of specification → Replace.

Coolant temperature sensor re-

b. Set the main switch to “ON”. sistance
c. Elevate the front wheel and slowly rotate it. 2.32–2.59 kΩ at 20 °C (68 °F)
d. Measure the voltage of gray and gray/black. 310–326 Ω at 80 °C (176 °F)
With each full rotation of the front wheel, the
voltage reading should cycle from 0.6 V to 4.8 ▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼
a. Connect the pocket tester (Ω × 1k/× 100) to
V to 0.6 V to 4.8 V.
the coolant temperature sensor terminals as
▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲
shown.
EAS28250

CHECKING THE RADIATOR FAN MOTOR Pocket tester

1. Check: 90890-03112
• Radiator fan motor Analog pocket tester
Faulty/rough movement → Replace. YU-03112-C
▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼
a. Disconnect the radiator fan motor coupler b. Immerse the coolant temperature sensor “1”
from the wire harness. in a container filled with coolant “2”.
b. Connect the battery (DC 12 V) as shown. TIP
• Positive tester probe → Make sure the coolant temperature sensor ter-
red “1” minals do not get wet.
• Negative tester probe →
black “2” c. Place a thermometer “3” in the coolant.

8-87
 ELECTRICAL COMPONENTS

Throttle position sensor voltage

3 5V
1 (gray/red–gray/black)

c. Connect the digital circuit tester to the throttle

position sensor as shown.
• Positive tester probe →
2 yellow “1”
• Negative tester probe →
gray/black “2”
d. Heat the coolant or let it cool down to the
specified temperatures.
e. Measure the coolant temperature sensor re-
sistances. Y Gy/B Gy/R
▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲
3. Install:
• Coolant temperature sensor

Coolant temperature sensor

18 Nm (1.8 m·kgf, 13 ft·lbf) 1 2
T.
R.

EAS28300

CHECKING THE THROTTLE POSITION d. While slowly opening the throttle, check that
SENSOR the throttle position sensor voltage is in-
1. Check: creased.
• Throttle position sensor Voltage does not change or it changes
▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼
abruptly → Replace the throttle position sen-
a. Connect the digital circuit tester to the throttle sor.
position sensor as shown. Out of specification (closed position) → Re-
place the throttle position sensor.
Digital circuit tester
90890-03174 Throttle position sensor voltage
Model 88 Multimeter with ta- (closed position)
chometer 0.40–0.90 V
YU-A1927 (yellow–gray/black)

• Positive tester probe → ▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲

gray/red “1” EAS28410

• Negative tester probe → CHECKING THE INTAKE AIR PRESSURE

gray/black “2” SENSOR
1. Check:
• Intake air pressure sensor output voltage
Out of specification → Replace.
Y Gy/B Gy/R
Intake air pressure sensor output
voltage
3.57–3.71 V

▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼
a. Connect the test harness between the intake
2 1 air pressure sensor and wire harness.
b. Connect the pocket tester (DC 20 V) to the
b. Measure the throttle position sensor voltage.
test harness.
Out of specification → Replace or repair the
wire harness.

8-88
 ELECTRICAL COMPONENTS

Test harness Pocket tester

90890-03204 90890-03112
Pocket tester Analog pocket tester
90890-03112 YU-03112-C
Analog pocket tester
YU-03112-C b. Immerse the intake air temperature sensor
“1” in a container filled with water “2”.
• Positive tester probe → TIP
pink/white “1” Make sure that the intake air temperature sensor
• Negative tester probe → terminals do not get wet.
gray/black “2”
c. Place a thermometer “3” in the water.

3 1
Gy/B P/W Gy/R

2 1 2

c. Set the main switch to “ON”.

d. Measure the intake air pressure sensor out- d. Heat the water or let it cool down to the spec-
put voltage. ified temperature.
e. Measure the intake air temperature sensor
▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲
resistance.
EAS28420

CHECKING THE INTAKE AIR ▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲

TEMPERATURE SENSOR EAS37P1083

1. Remove: CHECKING THE AIR TEMPERATURE

• Intake air temperature sensor SENSOR
(from the air filter case) 1. Remove:
EWA14110 • Air temperature sensor
WARNING EWA37P1017

WARNING
• Handle the intake air temperature sensor
with special care. • Handle the air temperature sensor with
• Never subject the intake air temperature special care.
sensor to strong shocks. If the intake air • Never subject the air temperature sensor to
temperature sensor is dropped, replace it. strong shocks. If the air temperature sen-
sor is dropped, replace it.
2. Check:
• Intake air temperature sensor resistance 2. Check:
Out of specification → Replace. • Air temperature sensor resistance
Out of specification → Replace.
Intake air temperature sensor re-
sistance Air temperature sensor resis-
2.21–2.69 kΩ at 20 °C (68 °F) tance
4.19–4.63 kΩ at 50 °C (122 °F)
▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼
a. Connect the pocket tester (Ω × 1k) to the in- ▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼
take air temperature sensor terminal as a. Connect the pocket tester (Ω × 1k) to the air
shown. temperature sensor terminal as shown.

8-89
 ELECTRICAL COMPONENTS

• Positive tester probe →

Pocket tester green “3”
90890-03112 • Negative tester probe →
Analog pocket tester sky blue “4”
YU-03112-C

b. Immerse the air temperature sensor “1” in a

container filled with water “2”.
4 2
TIP
Make sure that the air temperature sensor termi- Lg Sb
nals do not get wet.
P G
c. Place a thermometer “3” in the water.
3 1

3 c. Measure the ISC unit resistance.

1 Out of specification → Replace the throttle
body.

ISC unit resistance

27–33 Ω at 20 °C (68 °F)
2
▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲
d. Heat the water or let it cool down to the spec- EAS37P1084

ified temperatures. CHECKING THE V-BELT REPLACEMENT

e. Measure the air temperature sensor resis- INDICATOR RESET COUPLER
tance. 1. Remove:
▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲
• V-belt replacement indicator reset coupler
2. Check:
EAS37P1085

CHECKING THE ISC (IDLE SPEED • V-belt replacement indicator reset coupler
CONTROL) UNIT Out of specification → Replace the V-belt re-
placement indicator coupler.
TIP
Do not remove the ISC unit completely from the Continuity
throttle body. Positive tester probe → black
“1”
1. Check: Negative tester probe → black
• ISC unit “2”
▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼ Continuity
a. Disconnect the ISC unit coupler from the ISC Positive tester probe → black
unit. “2”
b. Connect the pocket tester (Ω × 10) to the ter- Negative tester probe → black
minals of the ISC unit. “1”
Pocket tester
90890-03112
1 2
Analog pocket tester
YU-03112-C

• Positive tester probe → B B

pink “1”
• Negative tester probe →
light green “2”

8-90
 ELECTRICAL COMPONENTS

▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼
a. Connect the pocket tester (Ω × 1) to the V-
belt replacement indicator reset coupler ter-
minals.

Pocket tester
90890-03112
Analog pocket tester
YU-03112-C

b. Check the V-belt replacement indicator reset

coupler for continuity.
▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲

8-91
 TROUBLESHOOTING

TROUBLESHOOTING..................................................................................... 9-1
GENERAL INFORMATION ....................................................................... 9-1
STARTING FAILURE/HARD STARTING.................................................. 9-1
INCORRECT ENGINE IDLING SPEED .................................................... 9-1
POOR MEDIUM-AND-HIGH-SPEED PERFORMANCE ........................... 9-2
FAULTY CLUTCH ..................................................................................... 9-2
OVERHEATING ........................................................................................ 9-2
OVERCOOLING........................................................................................ 9-3
POOR BRAKING PERFORMANCE.......................................................... 9-3
FAULTY FRONT FORK LEGS.................................................................. 9-3
UNSTABLE HANDLING ............................................................................ 9-3
FAULTY LIGHTING OR SIGNALING SYSTEM ........................................ 9-3

9
 TROUBLESHOOTING

EAS28450
Electrical system
TROUBLESHOOTING 1. Battery
EAS28460
• Discharged battery
GENERAL INFORMATION • Faulty battery
TIP 2. Fuse(s)
• Blown, damaged or incorrect fuse
The following guide for troubleshooting does not
• Improperly installed fuse
cover all the possible causes of trouble. It should
3. Spark plug
be helpful, however, as a guide to basic trouble-
• Incorrect spark plug gap
shooting. Refer to the relative procedure in this
• Incorrect spark plug heat range
manual for checks, adjustments, and replace-
• Fouled spark plug
ment of parts.
• Worn or damaged electrode
EAS28480
• Worn or damaged insulator
STARTING FAILURE/HARD STARTING • Faulty spark plug cap
4. Ignition coil
Engine • Cracked or broken ignition coil body
1. Cylinder and cylinder head • Broken or shorted primary or secondary coils
• Loose spark plug • Faulty spark plug lead
• Loose cylinder head or cylinder 5. Ignition system
• Damaged cylinder head gasket • Faulty ECU
• Damaged cylinder gasket • Faulty crankshaft position sensor
• Worn or damaged cylinder • Broken generator rotor woodruff key
• Incorrect valve clearance 6. Switches and wiring
• Improperly sealed valve • Faulty main switch
• Incorrect valve-to-valve-seat contact • Broken or shorted wiring
• Incorrect valve timing • Faulty front, rear or both brake light switches
• Faulty valve spring • Faulty start switch
• Seized valve • Faulty sidestand switch
2. Piston and piston ring(s) • Improperly grounded circuit
• Improperly installed piston ring • Loose connections
• Damaged, worn or fatigued piston ring 7. Starting system
• Seized piston ring • Faulty starter motor
• Seized or damaged piston • Faulty starter relay
3. Air filter • Faulty starting circuit cut-off relay
• Improperly installed air filter • Faulty starter clutch
• Clogged air filter element EAS28500
4. Crankcase and crankshaft INCORRECT ENGINE IDLING SPEED
• Improperly assembled crankcase
• Seized crankshaft Engine
1. Cylinder and cylinder head
Fuel system • Incorrect valve clearance
1. Fuel tank • Damaged valve train components
• Empty fuel tank 2. Air filter
• Clogged fuel tank cap breather hole • Clogged air filter element
• Deteriorated or contaminated fuel
• Clogged or damaged fuel hose Fuel system
2. Fuel pump 1. Throttle body
• Faulty fuel pump • Damaged or loose throttle body joint
• Clogged fuel pump filter • Improper throttle cable free play
3. Throttle body
• Deteriorated or contaminated fuel Electrical system
• Sucked-in air 1. Battery
• Discharged battery

9-1
 TROUBLESHOOTING

• Faulty battery 2. Primary sliding sheave

2. Spark plug • Faulty operation
• Incorrect spark plug gap 3. Clutch shoe(s)
• Incorrect spark plug heat range • Bent, damaged or worn clutch shoe
• Fouled spark plug
• Worn or damaged electrode Poor speed performance
• Worn or damaged insulator 1. V-belt
• Faulty spark plug cap • Oil or grease on the V-belt
3. Ignition coil 2. Primary pulley weight(s)
• Faulty spark plug lead • Faulty operation
4. Ignition system • Worn primary pulley weight
• Faulty ECU 3. Primary fixed sheave
• Faulty crankshaft position sensor • Worn primary fixed sheave
4. Primary sliding sheave
EAS28510

POOR MEDIUM-AND-HIGH-SPEED • Worn primary sliding sheave

PERFORMANCE 5. Secondary fixed sheave
Refer to “STARTING FAILURE/HARD START- • Worn secondary fixed sheave
ING” on page 9-1. 6. Secondary sliding sheave
• Worn secondary sliding sheave
Engine EAS28600

1. Air filter OVERHEATING

• Clogged air filter element
Engine
Fuel system 1. Clogged coolant passages
1. Fuel pump • Cylinder head and piston
• Faulty fuel pump • Heavy carbon buildup
2. Engine oil
EAS28580

FAULTY CLUTCH • Incorrect oil level

• Incorrect oil viscosity
Engine operates but vehicle will not move • Inferior oil quality
1. V-belt
• Bent, damaged or worn V-belt Cooling system
• Slipping V-belt 1. Coolant
2. Primary pulley cam and primary pulley slid- • Low coolant level
er(s) 2. Radiator
• Damaged or worn primary pulley cam • Damaged or leaking radiator
• Damaged or worn primary pulley slider • Faulty radiator cap
3. Transmission gear(s) • Bent or damaged radiator fin
• Damaged transmission gear 3. Water pump
• Damaged or faulty water pump
Clutch slips 4. Thermostat
1. Clutch shoe spring(s) • Thermostat stays closed
• Damaged, loose or worn clutch shoe spring 5. Hose(s)
2. Clutch shoe(s) • Damaged hose
• Damaged or worn clutch shoe • Improperly connected hose
3. Primary sliding sheave
• Seized primary sliding sheave Fuel system
1. Throttle body
Poor starting performance • Damaged or loose throttle body joint
1. V-belt 2. Air filter
• V-belt slips • Clogged air filter element
• Oil or grease on the V-belt

9-2
 TROUBLESHOOTING

Chassis EAS28670

UNSTABLE HANDLING
1. Brake(s)
1. Handlebar
• Dragging brake
• Bent or improperly installed handlebar
Electrical system 2. Steering head components
1. Spark plug • Improperly installed lower handlebar holder
• Incorrect spark plug gap • Improperly installed lower bracket
• Incorrect spark plug heat range (improperly tightened ring nut)
2. Ignition system • Bent steering stem
• Faulty ECU • Damaged ball bearing or bearing race
3. Front fork leg(s)
EAS28610 • Uneven oil levels (both front fork legs)
OVERCOOLING • Unevenly tensioned fork spring (both front
fork legs)
Cooling system • Broken fork spring
1. Thermostat • Bent or damaged inner tube
• Thermostat stays open • Bent or damaged outer tube
EAS28620 4. Swingarm
POOR BRAKING PERFORMANCE • Worn bearing or bushing
• Worn brake pad • Bent or damaged swingarm
• Worn brake disc 5. Rear shock absorber assembly(-ies)
• Air in hydraulic brake system • Faulty rear shock absorber spring
• Leaking brake fluid • Leaking oil
• Faulty brake caliper kit 6. Tire(s)
• Faulty brake caliper seal • Uneven tire pressures (front and rear)
• Loose union bolt • Incorrect tire pressure
• Damaged brake hose • Uneven tire wear
• Oil or grease on the brake disc 7. Wheel(s)
• Oil or grease on the brake pad • Incorrect wheel balance
• Incorrect brake fluid level • Deformed cast wheel
EAS28660
• Damaged wheel bearing
FAULTY FRONT FORK LEGS • Bent or loose wheel axle
• Excessive wheel runout
Leaking oil 8. Frame
• Bent, damaged or rusty inner tube • Bent frame
• Cracked or damaged outer tube • Damaged steering head pipe
• Improperly installed oil seal • Improperly installed bearing race
• Damaged oil seal lip EAS28710
• Incorrect oil level (high) FAULTY LIGHTING OR SIGNALING SYSTEM
• Loose damper rod bolt
• Damaged damper rod bolt copper washer Headlight does not come on
• Cracked or damaged front fork cap O-ring • Wrong headlight bulb
• Too many electrical accessories
Malfunction • Hard charging
• Bent or damaged inner tube • Incorrect connection
• Bent or damaged outer tube • Improperly grounded circuit
• Damaged fork spring • Poor contacts (main switch)
• Worn or damaged outer tube bushing • Burnt-out headlight bulb
• Bent or damaged damper rod
• Incorrect oil viscosity Headlight bulb burnt out
• Incorrect oil level • Wrong headlight bulb
• Faulty battery
• Faulty rectifier/regulator

9-3
 TROUBLESHOOTING

• Improperly grounded circuit

• Faulty main switch
• Headlight bulb life expired

Tail/brake light does not come on

• Wrong tail/brake light bulb
• Too many electrical accessories
• Incorrect connection
• Burnt-out tail/brake light bulb

Tail/brake light bulb burnt out

• Wrong tail/brake light bulb
• Faulty battery
• Tail/brake light bulb life expired

Turn signal does not come on

• Faulty turn signal switch
• Faulty turn signal/hazard relay
• Burnt-out turn signal bulb
• Incorrect connection
• Damaged or faulty wire harness
• Improperly grounded circuit
• Faulty battery
• Blown, damaged or incorrect fuse

Turn signals flash slowly

• Faulty turn signal/hazard relay
• Faulty main switch
• Faulty turn signal switch
• Incorrect turn signal bulb

Turn signals remain lit

• Faulty turn signal/hazard relay
• Burnt-out turn signal bulb

Turn signals flash quickly

• Incorrect turn signal bulb
• Faulty turn signal/hazard relay
• Burnt-out turn signal bulb

Horn does not sound

• Damaged or faulty horn
• Faulty main switch
• Faulty horn switch
• Faulty battery
• Blown, damaged or incorrect fuse
• Faulty wire harness

9-4
EAS28740
57. License plate light EAS28750

WIRING DIAGRAM 58. Fuel sender COLOR CODE

YP125R/YP250R 2010 59. V-belt replacement indicator re- B Black
1. AC magneto set coupler Br Brown
2. Crankshaft position sensor 60. Meter assembly Ch Chocolate
61. Immobilizer system indicator Dg Dark green
3. Rectifier/regulator
G Green
4. Backup fuse (immobilizer unit light
Gy Gray
and meter assembly) 62. Multifunction meter L Blue
5. Main switch 63. Speedometer Lg Light green
6. ECU fuse 64. Tachometer O Orange
7. Radiator fan motor fuse 65. Engine oil change indicator P Pink
8. Turn signal/hazard fuse 66. V-belt replacement indicator R Red
9. Ignition fuse 67. Engine trouble warning light Sb Sky blue
10. Headlight fuse 68. Meter light W White
11. Signaling system fuse 69. High beam indicator light Y Yellow
70. Right turn signal indicator light B/L Black/Blue
12. Battery
B/R Black/Red
13. Main fuse 71. Left turn signal indicator light
B/W Black/White
14. Starter relay 72. Air temperature sensor Br/L Brown/Blue
15. Starter motor 73. Radiator fan motor Br/R Brown/Red
16. Diode 74. Radiator fan motor relay Br/W Brown/White
17. Frame ground 75. Self-diagnosis signal coupler G/B Green/Black
18. Sidestand switch 76. Immobilizer unit G/L Green/Blue
19. Fuel pump A. YP250R only G/R Green/Red
20. Starting circuit cut-off relay G/Y Green/Yellow
21. Right handlebar switch Gy/B Gray/Black
22. Start switch Gy/G Gray/Green
Gy/R Gray/Red
23. Hazard switch
L/B Blue/Black
24. Front brake light switch L/R Blue/Red
25. Coolant temperature sensor L/W Blue/White
26. Throttle position sensor L/Y Blue/Yellow
27. Intake air pressure sensor O/B Orange/Black
28. Intake air temperature sensor O/R Orange/Red
29. Lean angle sensor P/W Pink/White
30. Speed sensor R/B Red/Black
31. ECU (engine control unit) R/G Red/Green
32. Ignition coil R/L Red/Blue
R/W Red/White
33. Spark plug
R/Y Red/Yellow
34. Fuel injector W/B White/Black
35. O2 sensor W/R White/Red
36. ISC (idle speed control) unit W/Y White/Yellow
37. Auxiliary DC jack (OPTION) Y/G Yellow/Green
38. Horn Y/L Yellow/Blue
39. Turn signal/hazard relay
40. Headlight relay
41. Left handlebar switch
42. Dimmer switch
43. Pass switch
44. Turn signal switch
45. Horn switch
46. Rear brake light switch
47. Right tail/brake light assembly
48. Right rear turn signal light
49. Tail/brake light
50. Left tail/brake light assembly
51. Left rear turn signal light
52. Right front turn signal light
53. Left front turn signal light
54. Headlight assembly
55. Headlight
56. Auxiliary light
YAMAHA MOTOR ESPAÑA, S.A.
YP125R/YP250R 2010 YP125R/YP250R 2010 YP125R/YP250R 2010 YP125R/YP250R 2010 YP125R/YP250R 2010
WIRING DIAGRAM SCHÉMA DE CÂBLAGE SCHALTPLAN SCHEMA ELETTRICO DIAGRAMA ELÉCTRICO

W/R
Gy/B P/W Y/G Br/W L B/W W/R L/Y L/W L/R Sb B/R G B1 W/B
Gy/B W/R R W
2 G/R Y Gy/G Gy/R Gy/B Y/L R/G Gy R/B Lg G/B P B2 O/B O

L/R R/B L/Y G/Y Gy/B

R/B W/Y
W W R L/Y L/R
W W2 W W G/Y R/B (BLUE)
1 W2 W2 3 G/R Gy/B W/R
W3 W W3 W3 B B 18 25 32
19 Gy/B R/B

B R 17 B
Gy/R Gy/B Y G/R G/R O O
W W2 W3 R R
B R/B L/R 20 A
R
(BLUE)
(BLACK)
33 A
R Gy/R Gy/R A Gy/R Gy/R
B
B L/W L/Y
(BLACK) B
W/Y L/Y 26 Y Y A Y Y L
Gy/B Gy/R Gy/R Gy/B
13 (BLUE)
Gy/B Gy/B A Gy/B
Y Y
12 L/W
34
4 14 L/W
L/Y
O/B R/B R/L O/B WIRE HARNESS SUB-WIRE HARNESS

R/L R B
B L/W
21 L/W W/Y Gy/R (BLACK) (BLACK)

B
B Gy/B P/W Gy/R 27 P/W
Gy/B
P/W O/B O/B R/B

R
B B 22 23 24 (BLACK)
B
16
Gy/B
R 35
Br/W Gy/B 28 L/W 31 Gy/G Gy/G Gy/B

5 15 B
(GREEN)
ON Br/W Br/W B/R B/R R/B
Dg Br/W Ch
Br/R Br/R
OFF L/W W/Y G/Y Br B1 B2 R/B B/R
OPEN W L Gy/G Gy/B
Gy/R
R R LOCK Dg Br/W Ch Br G/Y
Br/L Br/L P
Ch Br/W Dg
Gy/R Y/G Gy/B 29 Y/G
Gy/B
Y/G (BLACK)
G/Y Br W/Y L/W

6 B1 P P
Lg Sb
Br/LBr/R R R/G R/G Lg Lg
G G 36 P G

7 Gy/R Sb Sb (BLACK)
R R/W Gy Gy/B Gy/R O/R B/W P
30 Gy
Gy/B Gy
8
Br/R Br/R2
G/B
9 W/B
B/W R/L Br/L R/B R/B
Y/L G/L R/B Y/L
10
R/G B2 B Br/L R/Y
R/W Lg Y/L
11 B2 B/W
Br/L Br

R/B
B/W Br/R2
R/Y R/Y2
76 Y/L
40 R/Y
Br/W Br
R/L R/W L/B Br/R2 39 P
38
R/B
R/Y2 W/B (BLACK)

G/L R/W 74 L/B W/B

Br/W
Br
L
R/B G/B
41 L/B R/Y Br/W P 37 R Br
B
G B
L G/B
B/W R/L
42 43 44 45 46
L
Y/L Y/L

Y/L B B
B/W 75 Y/L L R 73 Y G P B G/Y
R/L Dg Br/W Ch L/B R/Y Br
(BLACK) (BLACK)
G Y Dg Ch B G/Y Br
G Y G/Y B P
B
Ch Br/W Dg Br R/Y L/B

R/B
60 G/L R/L Y/L Br Y Dg Ch

Br
Sb
Gy
61 62 57 B Sb Br B

54 G Y Br Ch B Ch Dg Dg B 50 Ch Br G/Y 47 Dg Br G/Y

63 64 65 66 67 68 69 70 71 53 52 51 49 48 49
B 55 55 56 56

Sb Ch Br
B/L B G Br Br W
B B
B/L Gy B G/Y
Ch Dg Y R/B R/L Sb Y B G/Y B
G/L Br Y/L B/L Gy B
59 58 (BLACK)
Sb B B B Dg Br B
72 Br G
B Y
Br Ch
B G/Y
B Gy B B G/Y B
B2 B1 (BLACK)
B B
B1 B1 B/L
YP125R/YP250R 2010 YP125R/YP250R 2010 YP125R/YP250R 2010 YP125R/YP250R 2010 YP125R/YP250R 2010
WIRING DIAGRAM SCHÉMA DE CÂBLAGE SCHALTPLAN SCHEMA ELETTRICO DIAGRAMA ELÉCTRICO

(BLUE)
1 3
18 25 32
19
17
20 A
(BLUE)
(BLACK)
33 A
A

(BLACK)
26 A

13 (BLUE)
A
Y
12 34
4 14 WIRE HARNESS SUB-WIRE HARNESS

21 (BLACK) (BLACK)

27
22 23 24 (BLACK)

16
35
28 31
5 15 (GREEN)
ON
OFF
OPEN
LOCK
P 29 (BLACK)

6
36
7 (BLACK)
P
30
8
9
10
11

76
40
39 38
(BLACK)

74
41 37
42 43 44 45 46

75 73
(BLACK) (BLACK)

60

61 62 57
54 50 47
63 64 65 66 67 68 69 70 71 53 52 51 49 48 49
55 55 56 56

59 58 (BLACK)

72
(BLACK)