WORKSHOP MANUAL

GASOLINE,LPG ENGINE

WG972-E2,DF972-E2

KiSC issued 01, 2006 A

 TO THE READER

This Workshop Manual has been prepared to provide servicing personnel with
information on the mechanism, service and maintenance of KUBOTA Gasoline / LPG
Fuel Engine WG972-E2 and DF972-E2. It is divided into three parts, "General",
"Mechanism" and "Servicing".

■ General
Information on the general precautions, check and maintenance and special tools.

■ Mechanism
Information on the construction and function are included. This part should be
understood before proceeding with troubleshooting, disassembling and servicing.

■ Servicing
There are troubleshooting, servicing specification lists, checking and adjusting,
disassembling and assembling, and servicing which cover procedures, precautions,
factory specifications and allowable limits.

All information illustrations and specifications contained in this manual are based on
the latest product information available at the time of publication.
The right is reserved to make changes in all information at any time without notice.

July 2005
© KUBOTA Corporation 2005

KiSC issued 01, 2006 A

WG972-E2, DF972-E2, WSM SAFETY INSTRUCTIONS

SAFETY INSTRUCTIONS

SAFETY FIRST
This symbol, the industry’s “Safety Alert Symbol”, is used throughout this manual and on labels on
the machine itself to warm of the possibility of personal injury. Read these instructions carefully.
It is essential that you read the instructions and safety regulations before you attempt to repair or use
this unit.

DANGER : Indicates an imminently hazardous situation which, if not avoided, will result in
death or serious injury.

WARNING : Indicates a potentially hazardous situation which, if not avoided, could result in
death or serious injury.

CAUTION : Indicates a potentially hazardous situation which, if not avoided, may result in
minor or moderate injury.

■ IMPORTANT : Indicates that equipment or property damage could result if instructions are not
followed.

■ NOTE : Gives helpful information.

BEFORE SERVICING AND REPAIRING

• Read all instructions and safety instructions in this
manual and on your generator safety decals.
• Clean the work area and generator.
• Park the machine on a firm and level ground, and set
the parking brake.
• Lower the implement to the ground.
• Stop the engine, and remove the key.
• Disconnect the battery negative cable.
• Hang a “DO NOT OPERATE” tag in operator
station.

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WG972-E2, DF972-E2, WSM SAFETY INSTRUCTIONS

SAFETY STARTING
• Do not start the engine by shorting across starter
terminals or bypassing the safety start switch.
• Do not alter or remove any part of machine safety
system.
• Before starting the engine, make sure that all shift
levers are in neutral positions or in disengaged
positions.
• Never start the engine while standing on ground.
Start the engine only from operator’s seat.

SAFETY WORKING
• Do not work on the machine while under the influence
of alcohol, medication, or other substances or while
fatigued.
• Wear close fitting clothing and safety equipment
appropriate to the job.
• Use tools appropriate to the work. Mark shift tools,
parts, and procedures are not recommended.
• When servicing is performed together by two or more
persons, take care to perform all work safely.
• Do not work under the machine that is supported
solely by a jack. Always support the machine by
safety stands.
• Do not touch the rotating or hot parts while the engine
is running.
• Never remove the radiator cap while the engine is
running, or immediately after stopping. Otherwise, hot
water will spout out from radiator. Only remove
radiator cap when cool enough to touch with bare
hands. Slowly loosen the cap to first stop to relieve
pressure before removing completely.
• Escaping fluid (fuel or hydraulic oil) under pressure
can penetrate the skin causing serious injury. Relieve
pressure before disconnecting hydraulic or fuel lines.
Tighten all connections before applying pressure.

AVOID FIRES
• Fuel is extremely flammable and explosive under
certain conditions. Do not smoke or allow flames or
sparks in your working area.
• To avoid sparks from an accidental short circuit,
always disconnect the battery negative cable first and
connect it last.
• Battery gas can explode. Keep sparks and open
flame away from the top of battery, especially when
charging the battery.
• Mark sure that no fuel has been spilled on the engine.

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WG972-E2, DF972-E2, WSM SAFETY INSTRUCTIONS

VENTILATE WORK AREA

• If the engine must be running to do same work, make
sure the area is well ventilated. Never run the engine
in a closed area. The exhaust gas contains poisonous
carbon monoxide.

PREVENT ACID BURNS

• Sulfuric acid in battery electrolyte is poisonous. It is
strong enough to burn skin, clothing and cause
blindness if splashed into eyes. Keep electrolyte
away from eyes, hands and clothing. If you spill
electrolyte on yourself, flush with water, and get
medical attention immediately.

DISPOSE OF FLUIDS PROPERLY

• Do not pour fluids into the ground, down a drain, or
into a stream, pond, or lake. Observe relevant
environmental protection regulations when disposing
of oil, fuel, coolant, electrolyte and other harmful
waste.

PREPARE FOR EMERGENCIES

• Keep a first aid kit and fire extinguisher handy at all
times.
• Keep emergency numbers for doctors, ambulance
service, hospital and fire department near your
telephone.

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WG972-E2, DF972-E2, WSM IMPORTANT ITEMS OF EXHAUST EMISSION REGULATION

IMPORTANT ITEMS OF EXHAUST EMISSION

REGULATION
■ To conform with U.S. EPA and CARB SOREs (Small Off Road Engines) emission regulations, the WG972-E2 /
DF972-E2 engine must observe below items.

1. INLET AND EXHAUST SYSTEM

The WG972-E2 / DF972-E2 engine must use the below air cleaner and inlet pipe, and exhaust back pressure of the
muffler must be within the below values.

Part Part No.

Genuine air cleaner 1G657-1101-1
Genuine inlet pipe EG561-1164-1
W1028060

Brake horse power SAE net int. Allowable maximum exhaust back pressure
−1 19.6 kPa (147.1 mmHg) / 3600 min−1 (rpm)
23.1 kW (31.0 HP) / 3600 min (rpm)
W1028104

Any modifications to the fuel system or any adjustments made on this engine will cause this engine to be in
non-compliance with emission regulations.

2. ALTITUDE COMPENSATION KIT

■ IMPORTANT
● Altitude compensation kit is applied for EPA and CARB certified engines only.
EPA and CARB emission regulations require the ultimate user of non-road SI engine, as their obligation,
to adjust the emissions by installing the appropriate genuine altitude compensation kit. And the engine
manufacturer must provide such kit when the engine is operated at an altitude that exceeds the standard
level, as guarantied by the engine manufacturer. For this purpose, KUBOTA prepared genuine altitude
compensation kit described below. The ultimate users of SI engines must comply with the regulations
through the installation of the appropriate altitude compensation kit for the altitude range where the
engine will be operated.
● See page S-19: "Replacement of Altitude Compensation Kit" for reference to the exchange of altitude
compensation kit.

Altitude Compensation Kit Applicable Altitude Ranges

Original Carburetor (with 0 m kit)

1000 m compensation kit

2000 m compensation kit

W1034885

3. LPG REGULATOR WITH VAPORIZER (DF972-E2)

When operating DF972-E2 on LP Gas, only a KUBOTA GENUINE LPG REGULATOR KIT can be used.
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WG972-E2, DF972-E2, WSM IMPORTANT ITEMS OF EXHAUST EMISSION REGULATION

4. KUBOTA RECOMMENDED LPG FUEL SPECIFICATIONS (DF972-E2)

· Commercial Propane gas only.
· Equivalent to Propanes H-D-5 of GPA* standards.

(vol %)
C3 H8 C3 H6 C4H10 Others
90 % 5% 2.5 % –
*GPA means Gas Processors Association (U.S.A.)
W1028533

5. LENGTH OF THE LPG VAPOR HOSE (DF972-E2)

The length of the LPG vapor hose between the LPG carburetor and its regulator must be within 280 to 320 mm
(11.02 to 12.60 in.).
The incorrect use of the hose may not conform to EPA and CARB EMISSION REGULATIONS.

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WG972-E2, DF972-E2, WSM SPECIFICATIONS

SPECIFICATIONS
Model WG972-E2 DF972-E2
Number of Cylinder 3
Vertical, water cooled, 4-cycle Vertical, water cooled, 4-cycle Dual Fuel (Gasoline / LPG) engine
Type Gasoline engine
Gasoline fuel LPG fuel
Bore × Stroke 74.5 x 73.6 mm (2.93 x 2.90 in.)
Total Displacement 962 cm3 (58.70 cu.in.)
18.7 kW / 3600 min-1 (rpm) 17.5 kW / 3600 min-1 (rpm)
ISO Net Continuous
25.0 HP / 3600 min-1 (rpm) 23.5 HP / 3600 min-1 (rpm)
23.1 kW / 3600 min-1 (rpm) 22.0 kW / 3600 min-1 (rpm)
ISO / SAE Net Intermittent
31.0 HP / 3600 min-1 (rpm) 29.5 HP / 3600 min-1 (rpm)
24.2 kW / 3600 min-1 (rpm) 23.1 kW / 3600 min-1 (rpm)
SAE Gross Intermittent
32.5 HP / 3600 min-1 (rpm) 31.0 HP / 3600 min-1 (rpm)
Maximum Bare Speed 3850 to 3950 min-1 (rpm)
Minimum Bare Idling Speed 1400 to 1600 min-1 (rpm)
Cylinder Head Overhead-Valve
Ignition System Distributor-Less Solid Stage Type
Governor Centrifugal Ball Mechanical Type / Electronic Governor
Direction of Rotation Counter-Clockwise (Viewed from flywheel)
Spark Plug NGK BKR4E
Ignition Timing 0.366 rad (21 °) before T.D.C. / 3600 min-1 (rpm)
Firing Order 1-2-3
Compression Ratio 9.2 : 1
Lubricating System Forced Lubrication by Trochoid Pump
Oil Pressure Indication Electrical Type Switch
Lubricating Filter Full Flow Paper Filter (Cartridge Type)
Cooling System Pressurized Radiator (not included in the basic model), Forced Circulation with Water Pump
Starting System Electric Starting with Starter
Starting Motor 12V, 1.0 kW
Battery 12 V, 2.5 kW
Charging Alternator 12 V, 150 W
Fuel *Unleaded Automobile Gasoline Standard Commercial LP Gas
Lubricating Oil Better than SH Class (API)
Lubricating Oil Capacity 3.4 L (3.59 U.S.qts)
Weight (Dry) 72.0 kg (158.7 lbs)
Application General Power Source
* The specification described above is of the standard engine of each model.
* Conversion Formula : HP = 0.746 kW, PS = 0.7355 kW
W1028103

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WG972-E2, DF972-E2, WSM SPECIFICATIONS

KUBOTA RECOMMENDED LPG FUEL SPECIFICATIONS

· Commercial Propane gas only.
· Equivalent to Propanes H-D-5 of GPA* standards.

(vol %)
C3 H8 C3H6 C4H10 Others
90 % 5% 2.5 % –
*GPA means Gas Processors Association (U.S.A.)
W1032351

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WG972-E2, DF972-E2, WSM PERFORMANCE CURVES

PERFORMANCE CURVES

(1) Brake Horsepower (5) Net Intermittent Torque (8) Net Continuous Brake a : Gasoline Use
(2) Engine Speed (6) Net Continuous Torque Horsepower b : LP Gas Use
(3) Specific Fuel Consumption (7) Net Intermittent Brake (9) Net Intermittent Specific Fuel
(4) Torque Horsepower Consumption

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WG972-E2, DF972-E2, WSM DIMENSIONS

DIMENSIONS

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WG972-E2, DF972-E2, WSM DIMENSIONS

Electronic Governor Model

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WG972-E2, DF972-E2, WSM WIRING DIAGRAM

WIRING DIAGRAM
Color of Wiring
B ........ Black BY ...... Black / Yellow GW ...... Green / White LW....... Blue / White R ....... Red Y ...... Yellow
BOr ......Black / Red Br ....... Brown Gr...... Gray Or ....... Orange RB ...... Red / Black YW ....... Yellow / White
BR ........Black / Red G ....... Green L....... Blue Pi ....... Pink RW ...... Red / White
BW ...... Black / White GY ..... Green / Yellow LB ...... Blue / Black Pu ...... Purple W ...... White

A
B
C
D 17 19
Terminal 30
Alternator
Sensor Assy, Crank Position 50 AC
Igniter 2 R 19 30 17 50 AC
B
L 3
1 1 IG 19 AC
G Sensor
2 2 Ignition Coil 0 Starter Switch
E L Position 50 30
E E 1
12 V R R AVX 0.75 f
G G 1 1
B
2 2 B 2 50 30
F F
H H 19 AC
I I Engine Speed Pulse Output Fuse
L L Water Temp 0.85
K K RB RB
IG 1 Switch 10 A
J J WB WB 5.5A, AVX 0.75 f
LB
LB
Or
0.5 G 0.5 G
Or Or 0.5 BY 0.5 BY

5
4

4
5
Or 0.5 W 0.5 W
Oil Switch

RW
0.5 L 0.5 L

6
3

3
6
IG 2 AVX 2 2 BW 2 BW
3 R 3 R

7
2

2
7
AVX 3

0.5 B 0.5 B

8
1

1
8
IG 3 Fuse

3 R
3 R
WIRE HARNESS (IGNITER)

BR WB BY

R L W G Water Temp
Oil (-) Lamp
Starter Battery
Charge
R L W G Lamp
Relay
12 P BR WB BY
Driver
ER - 9 12
+
10 7 +5V
+ 6 8 Aux 1 +
1 12 V Pilot Box Assy
+
2 OV 1 2
Power Input + 4 11 MPU + Cavbuleter
GND - MPU - Aux - Engine Speed Sensor
Select Switch 5 3 (Gasoline)
Solenoid
Valve
Electronic Governor
(12 V, 17.3 , 0.7 A)
WIRE HARNESS (ELECTRONIC GOVERNOR) Fuel Pump
(1.5 A, 12 V)

3EBAAABZP002A
11 KiSC issued 01, 2006 A
 GENERAL

CONTENTS

1. ENGINE IDENTIFICATION ............................................................................. G-1

[1] MODEL NAME AND ENGINE SERIAL NUMBER ................................ G-1
[2] CYLINDER NUMBER ............................................................................... G-3
2. GENERAL PRECAUTIONS ............................................................................ G-4
3. MAINTENANCE CHECK LIST ....................................................................... G-5
4. CHECK AND MAINTENANCE ....................................................................... G-6
[1] DAILY CHECK POINTS........................................................................... G-6
[2] CHECK POINTS OF INITIAL 50 HOURS ............................................. G-8
[3] CHECK POINTS OF EVERY 50 HOURS ............................................. G-9
[4] CHECK POINTS OF EVERY 100 HOURS ......................................... G-10
[5] CHECK POINTS OF EVERY 200 HOURS ......................................... G-12
[6] CHECK POINTS OF EVERY 1000 HOURS ....................................... G-14
[7] CHECK POINTS OF EVERY 1 YEAR ................................................ G-16
[8] CHECK POINTS OF EVERY 2 YEARS............................................... G-19
5. SPECIAL TOOLS .......................................................................................... G-22

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WG972-E2, DF972-E2, WSM G GENERAL

1. ENGINE IDENTIFICATION
[1] MODEL NAME AND ENGINE SERIAL NUMBER
When contacting the manufacture, always specify your engine
model name and serial number.
The engine model and its serial number need to be identified
before the engine can be serviced or parts replaced.
■ Engine Serial Number
The engine serial number is an identified number for the engine.
It is marked after the engine model number.
It indicates month and year of manufacture as follows.
• Year of manufacture
Alphabet or Alphabet or
Year Year
Number Number
1 2001 F 2015
2 2002 G 2016
3 2003 H 2017
4 2004 J 2018
5 2005 K 2019
6 2006 L 2020
7 2007 M 2021
8 2008 N 2022
9 2009 P 2023
A 2010 R 2024
B 2011 S 2025
C 2012 T 2026
D 2013 V 2027
E 2014

a : Engine Model Name and Serial [A] WG972-E2

Number [B] DF972-E2
W1010477

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G-1
WG972-E2, DF972-E2, WSM G GENERAL

• Month of manufacture
Engine Serial Number
Month
0001 ~ 9999 10000 ~
January A0001 ~ A9999 B0001 ~
February C0001 ~ C9999 D0001 ~
March E0001 ~ E9999 F0001 ~
April G0001 ~ G9999 H0001 ~
May J0001 ~ J9999 K0001 ~
June L0001 ~ L9999 M0001 ~
July N0001 ~ N9999 P0001 ~
August Q0001 ~ Q9999 R0001 ~
September S0001 ~ S9999 T0001 ~
October U0001 ~ U9999 V0001 ~
November W0001 ~ W9999 X0001 ~
December Y0001 ~ Y9999 Z0001 ~

e.g. DF972-4A0001
"WG" indicates Water Cooled and Gasoline Engine.
"DF" indicates Dual Fuel Engine.
"4" indicates 2004 and "A" indicates January.
So, 4A indicates that the engine was manufactured on January,
2004.
W1011076
■ Emission Label
This label is attached on the cylinder head cover of the engine
certified to the requirements of EPA / CARB Emission regulations.
The content of the label is approved officially by EPA / CARB.

W1025355

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WG972-E2, DF972-E2, WSM G GENERAL

■ Tamper Resistance
KUBOTA Corporation is to provide safeguards for the parts
where never to be adjusted, and is approved by EPA / CARB for the
purpose of this engine to be in compliance with EPA / CARB
Emission Regulations through its useful life. Intentional removal and
adjustment of such tamper resistance are subject to the penalty.
(1) Tamper Resistance [A] Carburetor
[B] Pick-up Sensor
[C] Vaporizer
W1025903

[2] CYLINDER NUMBER

The cylinder numbers of KUBOTA gasoline / LPG engine are
designated as shown in the figure.
The sequence of cylinder numbers is given as No.1, No.2 and
No.3 starting from the gear case side.
W1011077

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WG972-E2, DF972-E2, WSM G GENERAL

2. GENERAL PRECAUTIONS
• During disassembly, carefully arrange removed parts in a clean
area to prevent confusion later. Screws, bolts and nuts should be
replaced in their original position to prevent reassembly errors.
• When special tools are required, use KUBOTA genuine special
tools. Special tools which are not frequently used should be
made according to the drawings provided.
• Before disassembling or servicing live wires, make sure to
always disconnect the grounding cable from the battery first.
• Remove oil and dirt from parts before measuring.
• Use only KUBOTA genuine parts for parts replacement to
maintain engine performance and to ensure safety.
• Gaskets and O-rings must be replaced during reassembly.
Apply grease to new O-rings or oil seals before assembling.
• When reassembling external or internal snap rings, position them
so that the sharp edge faces against the direction from which
force is applied.
• Be sure to perform run-in the serviced or reassembled engine.
Do not attempt to give heavy load at once, or serious damage
may result to the engine.
(1) Grease (A) External Snap Ring
(2) Force (B) Internal Snap Ring
(3) Place the Sharp Edge against the
Direction of Force

W1011734

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WG972-E2, DF972-E2, WSM G GENERAL

3. MAINTENANCE CHECK LIST

To maintain long-lasting and safe engine performance, make it a rule to carry out regular inspections by following
the table below. (The schedule applies to an engine in use under normal conditions.)
Service Interval
Item Every 50 Every Every Every 1 Every Every 2
Daily hrs 100 hrs 200 hrs year 1000 hrs years
Changing LPG fuel connector ✩
Checking engine oil level ✩
Checking and replenish coolant ✩
Checking gasoline fuel hose and clamp bands ✩
Changing LPG fuel hose and clamp bands ✩
Cleaning air cleaner element ✩
Checking battery electrolyte level ✩
Checking spark plug ✩
Cleaning fuel filter ✩
Check fan belt tension and damage ✩
Replacing oil filter cartridge ★ ✩
Changing engine oil ★ ✩
Check LPG tank setting condition ✩
Checking radiator hoses and clamp bands ✩
*Replacing air cleaner element ✩
Replacing gosoline fuel hose and clamp bands ✩
Cleaning carburetor ✩
Cleaning fuel tank inside ✩
Replacing spark plug ✩
Checking coolant hose of LPG vaporizer ✩
Checking vacume lock hose of LPG vaporizer ✩
Changing radiator coolant (L.L.C.) ✩
Cleaning water jacket and radiator inteirior ✩
Checking valve clearance ✩
Cleaning cylinder head ✩
Checking valve seats ✩
Replacing intake air line ✩
Replacing fuel filter ✩
Replacing LPG fuel hose and clamp bands ✩
Replacing coolant hose of LPG vaporizer ✩
Replacing vacume lock hose of LPG vaporizer ✩
Replacing battery ✩
Replacing radiator hoses and clamp bands ✩

★ Change engine oil and replace oil filter cartridge after the firtst 50 hours of operation.
* Replace the element after 6 times cleaning.

CAUTION
• When changing or inspecting, be sure to level and stop the engine.

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WG972-E2, DF972-E2, WSM G GENERAL

4. CHECK AND MAINTENANCE

[1] DAILY CHECK POINTS
Checking Engine Oil Level
1. Level the engine.
2. To check the oil level, draw out the dipstick (1), wipe it clean,
reinsert it, and draw it out again.
Check to see that the oil level lies between the two notches.
3. If the level is too low, add new oil to the specified level.
■ IMPORTANT
• When using an oil of different maker or viscosity from the
previous one, drain old oil. Never mix two different types of
oil.
■ IMPORTANT
• Use the proper SAE Engine oil according to ambient
temperatures.
■ NOTE
• Be sure to inspect the engine, locating it on a horizontal
place. If placed on gradients, accurately, oil quantity may
not be measured.
• Be sure to keep the oil level between upper and lower limits
of the dipstick. Too much oil may cause a drop in output or
excessive blow-by gas. On the closed breather type engine
in which mist is sucked through port, too much oil may
caused oil hammer. While too little oil, may seize the
engine’s rotating and sliding parts.
(1) Dipstick
W1035676

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WG972-E2, DF972-E2, WSM G GENERAL

Checking and Replenish Coolant

1. Without recovery tank :
Remove the radiator cap (1) and check to see that the coolant
level is just below the port.
With recovery tank (2) :
Check to see that the coolant level lies between FULL (A) and
LOW (B).
2. If coolant level is too low, check the reason for decreasing
coolant.
(Case 1)
If coolant is decreasing by evaporation, replenish only fresh, soft
water.
(Case 2)
If coolant is decreasing by leak, replenish coolant of the same
manufacture and type in the specified mixture ratio (fresh, soft
water and L.L.C.). If the coolant brand cannot be identified, drain
out all of the remaining coolant and refill with a totally new brand
of coolant mix.

CAUTION
• Do not remove the radiator cap until coolant temperature is
below its boiling point. Then loosen the cap slightly to
relieve any excess pressure before removing the cap
completely.
■ IMPORTANT
• During filling the coolant, air must be vented from the engine
coolant passages. The air vents by jiggling the radiator
upper and lower hoses.
• Be sure to close the radiator cap securely. If the cap is loose
or improperly closed, coolant may leak out and the engine
could overheat.
• Do not use an antifreeze and scale inhibitor at the same time.
• Never mix the different type or brand of L.L.C..
(1) Radiator Cap A : FULL
(2) Recovery Tank B : LOW
W1035779

Checking Air Cleaner Element (If necessary)

1. Remove the dust cup in the air cleaner.
2. Check the dust in the dust cup and the element.
(When reassembling)
• Install the air cleaner dust cup with "TOP" indicated on the rear
of the cup.
(1) Dipstick (3) “TOP” Mark
(2) Element
W1029733

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WG972-E2, DF972-E2, WSM G GENERAL

Checking Air Cleaner Element (If necessary)

1. To clean the element, use clean dry compressed air on the inside
of the element.
Air pressure at the nozzle must be under 205 kPa (2.1 kgf/cm2,
30 psi).
2. If the element is stained with carbon or oil, replace the element.
■ IMPORTANT
• Make sure the wing bolt for the element is tight enough. If it
is loose, dust and dirt may be sucked, wearing down the
cylinder liner and piston ring earlier and thereby resulting in
poor power output.
• Do not overservice the air cleaner element.
■ NOTE
• Replace the element once a year or every 6th cleaning.

W1030585

Checking the Setting of LPG Fuel Tank (If necessary) (DF972-

E2)
Check the setting of LPG fuel tank.
W1031085

Checking the Connector (DF972-E2)

Check the connector in LPG line (hoses and clamps).
W1031214

[2] CHECK POINTS OF INITIAL 50 HOURS

Changing Engine Oil

CAUTION
• Be sure to stop engine before changing engine oil.
1. Start and warm up the engine for approx. 5 minutes.
2. Place an oil pan underneath the engine.
3. To drain the used oil, remove the drain plug (1) at the bottom of
the engine and drain the oil completely.
4. Screw the drain plug (1).
5. Fill new oil up to upper line on the dipstick (2).
■ IMPORTANT
• When using an oil of different maker or viscosity from the
previous one, remove all of the old oil.
• Never mix two different types of oil.
• Engine oil should have properties of API classification SH.
• Use the proper SAE Engine Oil according to ambient
temperature.
Above 25 °C (77 °F) SAE30 or SAE10W-30
0 °C to 25 °C (32 °F to 77 °F) SAE20 or SAE10W-30
Below 0 °C (32 °F) SAE10W or SAE10W-30

3.4 L
Engine oil capacity
3.59 U.S.qts

32.4 to 37.3 N·m

Tightening torque Drain plug 3.3 to 3.8 kgf·m
23.9 to 27.5 ft-lbs

(1) Drain Plug (2) Dipstick

W1016604

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WG972-E2, DF972-E2, WSM G GENERAL

Replacing Oil Filter Cartridge

CAUTION
• Be sure to stop the engine before changing filter cartridge.
1. Remove the oil filter cartridge (1) with the filter wrench.
2. Apply a slight coart of oil onto the new cartridge gasket.
3. To install the new cartridge, screw it in by hand. Over tightening
may cause deformation of rubber gasket.
4. After the new cartridge has been replaced, the engine oil
normally decrease a little. Thus see that the engine oil does not
leak through the seal and be sure to read the oil level on the
dipstick. Then, replenish the engine oil up to the specified level.
■ IMPORTANT
• To prevent serious damage to the engine, replacement
element must be highly efficient. Use only a KUBOTA
genuine filter or its equivalent.
(1) Engine Oil Filter Cartridge
W1017137

[3] CHECK POINTS OF EVERY 50 HOURS

Checking Air Cleaner Element
1. To clean the element, use clean dry compressed air on the inside
of the element.
Air pressure at the nozzle must be under 205 kPa (2.1 kgf/cm2,
30 psi).
2. If the element is stained with carbon or oil, replace the element.
■ IMPORTANT
• Make sure the wing bolt for the element is tight enough. If it
is loose, dust and dirt may be sucked, wearing down the
cylinder liner and piston ring earlier and thereby resulting in
poor power output.
• Do not overservice the air cleaner element.
■ NOTE
• Replace the element once a year or every 6th cleaning.
W1033184

CAUTION
• Stop the engine when attempting the check and replace prescribed below.
• Remember to check the fuel line periodically. The fuel line is subject to wear and aging, fuel may leak out
onto the running engine, causing a fire.
Checking Fuel Hose (Gasoline Fuel Line)
Check the fuel hoses every 100 hours of operation.
1. Since the fuel hose (2) is made of rubber, it ages regardless of
the period of service.
Replace the fuel hose together with the clamp every two years.
2. However, if the fuel hose and clamp are found to be damaged or
deteriorate earlier than two years, then replace or remedy.
3. After the fuel hose and the clamp have been replaced, bleed the
fuel system.
(1) Clamp (3) Fuel Hose
W1035921

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WG972-E2, DF972-E2, WSM G GENERAL

Checking Fuel Leakage (LPG Fuel Line) (DF972-E2)

■ IMPORTANT
• Never test for gas leaks with a FLAME.
■ NOTE
• Check for fuel leakage by using soapy water or gas-detector,
if leakage is found, correct leakage.
W1033401
LPG Fuel Check
1. Open the shutoff valve on the tank.
2. Check for
a : Fuel tank to filter
b : Filter tank to filter
c : Shutoff valve to vaporizer
W1033547
Gaseous Fuel Check
1. Check the hose clamp and vapor hose.
2. Confirm that there is no leakage form the vapor hose.
W1033668
Checking Battery Electrolyte Level
1. Check the battery electrolyte level.
2. If the level is below than lower level line, add the distilled water to
pour level of each cell.

CAUTION
• Never remove the vent plugs while the engine is running.
• Keep electrolyte away from eyes, hands and clothes.
If you are spattered with it, wash it away completely with
water immediately and get medical attention.
• Wear eye protection and rubber gloves when working
around battery.
W1033732

[4] CHECK POINTS OF EVERY 100 HOURS

Checking Spark Plug Gap
1. Remove the spark plug, and remove carbon from the electrode
with a wire brush or other tools.
2. Measure the spark plug gap with a feeler gauge, and repair or
replace the plug if the measured gap differs from the factory
specification.
3. Replace the plug if the electrode or the insulator is deformed or
cracked.
4. Tighten the plug with a plug wrench.
0.6 to 0.7 mm
Spark plug gap Factory spec.
0.024 to 0.028 in.

Spark plug NGK BKR4E

19.6 to 24.5 N·m

Tightening torque Spark plug 2.0 to 2.5 kgf·m
14.5 to 18.1 ft-lbs
W1014131

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WG972-E2, DF972-E2, WSM G GENERAL

Checking and Cleaning Fuel Filter (Gasoline Line)

1. Check the fuel filter.
2. If the fuel filter is dirty, clean it or replace it.

CAUTION
• Stop the engine when attempting to check and clean the fuel
filter.
• Gasoline fuel is extremely flamble, so avoid fires.
W1209480
Fan Belt Tension
1. Measure the deflection (A), depressing the belt halfway between
the fan drive pulley and alternator pulley at specified force 98 N
(10 kgf, 22 lbs).
2. If the measurement is not within the factory specifications, loosen
the alternator mounting screws and relocate the alternator to
adjust.
7.0 to 9.0 mm
Deflection (A) Factory spec.
0.28 to 0.35 in.

(A) Deflection
Fan Belt Damage and Wear
1. Check the fan belt for damage.
2. If the fan belt is damaged, replace it.
3. Check if the fan belt is worn and sunk in the pulley groove.
4. If the fan belt is nearly worn out and deeply sunk in the pulley
groove, replace it.
(A) Good (B) Bad

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WG972-E2, DF972-E2, WSM G GENERAL

[5] CHECK POINTS OF EVERY 200 HOURS

Changing Engine Oil

CAUTION
• Be sure to stop engine before changing engine oil.
1. Start and warm up the engine for approx. 5 minutes.
2. Place an oil pan underneath the engine.
3. To drain the used oil, remove the drain plug (1) at the bottom of
the engine and drain the oil completely.
4. Screw the drain plug (1).
5. Fill new oil up to upper line on the dipstick (2).
■ IMPORTANT
• When using an oil of different maker or viscosity from the
previous one, remove all of the old oil.
• Never mix two different types of oil.
• Engine oil should have properties of API classification SH.
• Use the proper SAE Engine Oil according to ambient
temperature.
Above 25 °C (77 °F) SAE30 or SAE10W-30
0 °C to 25 °C (32 °F to 77 °F) SAE20 or SAE10W-30
Below 0 °C (32 °F) SAE10W or SAE10W-30

3.4 L
Engine oil capacity
3.59 U.S.qts

32.4 to 37.3 N·m

Tightening torque Drain plug 3.3 to 3.8 kgf·m
23.9 to 27.5 ft-lbs

(1) Drain Plug (2) Dipstick

Replacing Engine Oil Filter Cartridge

CAUTION
• Be sure to stop the engine before changing filter cartridge.
1. Remove the oil filter cartridge (1) with the filter wrench.
2. Apply a slight coart of oil onto the new cartridge gasket.
3. To install the new cartridge, screw it in by hand. Over tightening
may cause deformation of rubber gasket.
4. After the new cartridge has been replaced, the engine oil
normally decrease a little. Thus see that the engine oil does not
leak through the seal and be sure to read the oil level on the
dipstick. Then, replenish the engine oil up to the specified level.
■ IMPORTANT
• To prevent serious damage to the engine, replacement
element must be highly efficient. Use only a KUBOTA
genuine filter or its equivalent.
(1) Engine Oil Filter Cartridge
W1036804
Checking the Setting of LPG Fuel Tank (DF972-E2)
Check the setting of LGP fuel tank.
W1015117

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WG972-E2, DF972-E2, WSM G GENERAL

Checking Radiator Hoses and Clamp Bands

1. Check to see if the radiator hoses are properly fixed every 200
hours of operation or every six months, whichever comes first.
2. If the clamp is loose, apply oil to the threads and retighten it
securely.
3. The water hose is made of rubber and tends to age. It must be
replaced every two years. Also replace the clamp and tighten it
securely.
(1) Upper Hose (2) Lower Hose

W1037062

KiSC issued 01, 2006 A

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WG972-E2, DF972-E2, WSM G GENERAL

[6] CHECK POINTS OF EVERY 1000 HOURS

Replacing the Spark Plug
1. Disconnect the spark plug cap (1).
2. Remove the spark plug.
3. Replace the new spark plug.
19.6 to 24.5 N·m
Tightening torque Spark plug 2.0 to 2.5 kgf·m
14.5 to 18.1 ft-lbs

(1) Spark Plug Cap

W1037215

Checking the Hot Water Hoses (DF972-E2)

1. Check the hot water hoses (1) for damage.
2. If the hot water hose is damaged, replace it.
(1) Hot Water Hoses to Vaporizer
W1037526

Checking the Vacuum Lock Hoses (DF972-E2)

1. Check the vacuum lock hose (1) for damage.
2. If the hose is damaged, replace it.
(1) Vacuum Lock Hoses
W1055412

Draining Tar (Vaporizer for DF972-E2)

1. Run the engine until it is warmed up.
2. The shut off valve is shut and the engine is stopped naturally.
3. Place an oil pan underneath the drain port.
4. Remove the drain plug (4), and drain tar.
5. Tighten the plug.
■ NOTE
• Apply a liquid gasket (Three Bond 1104 or equivalent) to the
thread of the plug.
(1) Vaporizer (4) Drain Plug
(2) Water Hose (5) Liquid Gasket
(3) Wrench (6) Joint
W1037642

KiSC issued 01, 2006 A

G-14
WG972-E2, DF972-E2, WSM G GENERAL

Adjusting the Valve Clearance

■ IMPORTANT
• The valve clearance must be checked and adjusted when
engine is cold.
1. Remove the cylinder head cover (1) and the spark plugs.
2. Align the “1TC” mark (2) on the flywheel and alignment mark (3)
on the rear end plate so that the No. 1 piston comes to the
compression top dead center.
3. Check the following valve clearance marked with “★” using a
thickness gauge.
4. If the clearance is not within the factory specifications, adjust with
the adjusting screw.
5. Then turn the flywheel 6.28 rad (360 °), and align the “1TC” mark
(2) on the flywheel and alignment mark (3) on the rear end plate
so that the No. 1 piston comes to the overlap position.
6. Check the following valve clearance marked with “✩” using a
feeler gauge.
7. If the clearance is not within the factory specifications, adjust with
the adjusting screw.
Engine Valve
arrangement
Intake valve Exhaust valve
Adjustable cylinder
location of piston
No. 1 ★ ★
No. 2 ✩ ★
No. 3 ★ ✩
★ : When No. 1 piston is at the compression top dead center position.
✩ : When No. 1 piston is at the overlap position.

Intake and exhaust 0.145 to 0.185 mm

Factory spec.
valve clearance (cold) 0.00571 to 0.00728 in.

■ NOTE
• The sequence of cylinder numbers is given as No. 1, No. 2
and No. 3 starting from the gear case side.
• After adjusting the valve clearance, secure the adjusting
screw with the lock nut.
(1) Cylinder Head Cover A : Gear Case Side
(2) “1TC” Mark
(3) Alignment Mark
W10172470

KiSC issued 01, 2006 A

G-15
WG972-E2, DF972-E2, WSM G GENERAL

Checking and Relapping the Valve Seats

1. Coat the valve face lightly with prussian blue and put the valve on
its seat to check the contact.
2. If the valve does not seat all the way around the valve seat or the
valve contact is less than 70 %, correct the valve seating as
follows.
3. If the valve contact does not comply with the reference value,
replace the valve or correct the contact of valve seating.
2.12 mm
Valve seat width Factory spec.
0.0835 in.

(1) Correct (3) Incorrect

(2) Incorrect
W10282190

[7] CHECK POINTS OF EVERY 1 YEAR

Replacing the Air Cleaner Element
1. Remove the dust cup from the air cleaner.
2. After cleaning the dust cup, remove the air cleaner element.
3. Replace the new air cleaner element.
(1) Air Cleaner Element
W1018144

Replacing Fuel Filter and Fuel Hose (for Gasoline Fuel)

1. Close the fuel tank cock.
2. Replace the fuel filter (1) with a new one.
3. Replace the hose (2) and clamp (3).
(1) Fuel Filter (3) Clamp
(2) Fuel Hose
W1039107

Cleaning the Fuel Tank (for Gasoline Fuel)

1. Following the unit / machine's operators manual, drain the
gasoline fuel in the fuel tank.
2. Clean the fuel tank inside.
W1039258

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G-16
WG972-E2, DF972-E2, WSM G GENERAL

Cleaning Water Jacket and Radiator Interior

CAUTION
• Do not remove the radiator cap when the engine is hot. Then
loosen cap slightly to the stop to relieve any excess
pressure before removing cap completely.
1. Stop the engine and let cool down.
2. To drain the coolant, open the radiator drain plug (2) and remove
the radiator cap (1). Then radiator cap (1) must be removed to
completely drain the coolant. And open the drain cock (3) of
engine body.
3. After all coolant is drained, close the drain plug.
4. Fill with clean water and cooling system cleaner.
5. Follow directions of the cleaner instruction.
6. After flushing, fill with clean water and anti-freeze until the coolant
level is just below the port. Install the radiator cap (1) securely.
7. Fill with coolant up to “FULL” (A) mark on the recovery tank (4).
8. Start and operate the engine for few minutes.
9. Stop the engine and let cool. Check coolant level of recovery
tank (4) and add coolant if necessary.
■ IMPORTANT
• Do not start engine without coolant.
• Use clean, fresh, soft water and anti-freeze to fill the radiator
and recovery tank.
• When the anti-freeze is mixed with fresh, soft water, the anti-
freeze mixing ratio must be less than 50 %.
• Securely tighten radiator cap. If the cap is loose or
improperly fitted, water may leak out and the engine could
overheat.
(1) Radiator Cap A : Full
(2) Drain Plug B : Low
(3) Drain Cock
(4) Recovery Tank
W1038102

KiSC issued 01, 2006 A

G-17
WG972-E2, DF972-E2, WSM G GENERAL

Anti-Freeze
• There are two types of anti-freeze available: use the permanent
type (PT) for this engine.
• Before adding anti-freeze for the first time, clean the radiator
interior by pouring fresh, soft water and draining it a few times.
• The procedure for mixing water and anti-freeze differs according
to the make of the anti-freeze and the ambient temperature.
Basically, it should be referred to SAE J1034 standard, more
specifically also to SAE J814c.
• Mix the anti-freeze with fresh, soft water, and then fill into the
radiator.
■ IMPORTANT
• When the anti-freeze is mixed with fresh, soft water, the anti-
freeze mixing ratio must be less than 50 %.
Vol % Freezing point Boiling point*
anti-freeze °C °F °C °F
40 –24 –11.2 106 222.8
50 –37 –34.6 108 226.4
* At 1.013 × 100000 Pa (760 mmHg) pressure (atmospheric). A
higher boiling point is obtained by using a radiator pressure cap
which permits the development of pressure within the cooling
system.
■ NOTE
• The above data represents industrial standards that
necessitate a minimum glycol content in the concentrated
anti-freeze.
• When the coolant level drops due to evaporation, add fresh,
soft water only to keep the anti-freeze mixing ratio less than
50 %. In case of leakage, add anti-freeze and fresh, soft
water in the specified mixing ratio.
• Anti-freeze absorbs moisture. Keep unused anti-freeze in a
tightly sealed container.
• Do not use radiator cleaning agents when anti-freeze has
been added to the coolant.
(Anti-freeze contains an anti-corrosive agent, which will
react with the radiator cleaning agent forming sludge which
will affect the engine parts.)
W1039218

KiSC issued 01, 2006 A

G-18
WG972-E2, DF972-E2, WSM G GENERAL

[8] CHECK POINTS OF EVERY 2 YEARS

Replacing the Intake Hose and Clamps
Replace the intake hose and the clamps between the air cleaner
and the carburetor.
W10411400
Replacing the Fuel Hose and the Clamps (LPG Line)
Replace the fuel hose and the clamps (LPG line).
W10403890
Replacing the Hot Water Hoses
1. Coonnect the water hose (1) and (2) through the vaporizer.
2. The water joint part of vaporizer is adjusted to the upper side (A)
and coolant is replenished through radiator, to bleed air in the
vaporizer.
(1) Water Hose A : Water Joint
(2) Water Hose
(3) Vaporizer
W10404360

Replace the Vacuum Lock Hoses

1. Coonnect the new vacuum lock hose (1).
(1) Vacuum Lock Hose
W10406390

KiSC issued 01, 2006 A

G-19
WG972-E2, DF972-E2, WSM G GENERAL

Checking Primary Chamber (Vaporizer for LPG Fuel)

■ IMPORTANT
• When checking the fuel system after completely consuming
the fuel in piping.
• Treat a seal tape or liquid gasket when install each
connector.
1. Run the engine until is warmed up.
2. The shut off valve is shut and the engine is stopped naturally.
3. Disconnect the plug (1).
4. Set the pressure gauge (2).
5. The shut off valve is opened and the engine is started, and check
the pressure.
6. If the pressure is not within the factory specification, replace the
vaporizer.
30.0 to 34.3 MPa
Pressure Factory spec. 0.30 to 0.35 kgf/cm2
4.4 to 4.9 psi

(1) Plug (2) Pressure Gauge

W1024942

Checking Air Tight of Secondary Chamber (Vaporizer for LPG

Fuel)
1. Disconnect the vapor hose (1) on the mixer side.
2. Breath is blown lightly or compressed air (9.8 kPa, 0.1 kgf/cm2
1.4 psi).
3. It is confirmed that the air does not leak.
4. If there is a leakage, replace the vaporizer.
(1) Vapor Hose
W10412390

Checking Vacuum Lock System

1. After warming up, and set the low idling speed.
5. Disconnect the vacuum lock hose (1), and close the joint
manifold by finger.
6. Confirm the thing that the engine stops.
(1) Vacuum Lock Hose (2) Joint
W10413080

KiSC issued 01, 2006 A

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WG972-E2, DF972-E2, WSM G GENERAL

Replacing Radiator Hoses and Clamp Bands

CAUTION
• Do not remove the radiator cap when the engine is hot. Then
loosen cap slightly to the stop to relieve any excess
pressure before removing cap completely.
1. Drain the coolant.
2. Loosen the clamp bands.
3. Remove the upper hose (1) and lower hose (2).
4. Replace new upper / lower hose (1), (2) and clamp bands.
5. Tighten the clamp bands.
6. Fill with clean water and anti-freeze until the coolant level is just
below the port. Install the radiator cap securely.
(1) Upper Hose (2) Lower Hose
W1024178

KiSC issued 01, 2006 A

G-21
WG972-E2, DF972-E2, WSM G GENERAL

5. SPECIAL TOOLS
Timing Light
Application : Use to adjust the ignition timing.
W1024318

Compression Tester
Code No : 07909-30251
Application : Use to measure gasoline engine compression
and diagnose the engine for a major overhaul.
W1042798

Oil Pressure Tester

Code No: 07916-32032
Application: Use to measure lubricating oil pressure.
(1) Gauge (5) Adaptor 2
(2) Cable (6) Adaptor 3
(3) Threaded Joint (7) Adaptor 4
(4) Adaptor 1 (8) Adaptor 5
W1043015

Radiator Tester
Code No: 07909-31551
Application: Use to check of radiator cap pressure, and leaks from
cooling system.
Remarks: Adaptor (1) BANZAI Code No. RCT-2A-30S
W1024532

Pressure Gauge
Specification : 98 kPa (1.0 kgf/cm2, 14 psi)
Application : Check the pressure of vaporizer.
W1045595

KiSC issued 01, 2006 A

G-22
WG972-E2, DF972-E2, WSM G GENERAL

Valve Guide Replacing Tool

Application: Use to press out and press fit the valve guide.
A 200 mm (7.87 in.)
B 80 mm (3.15 in.)
C 40 mm (1.58 in.)
D 20 mm dia. (0.79 in dia.)
E 9.96 to 9.98 mm dia. (0.3921 to 0.3929 in. dia.)
F 5.5 to 5.7 mm dia. (0.2165 to 0.2244 in.dia.)
G 15 mm (0.59 in.)
H 6.0 to 6.1 mm dia. (0.236 to 0.240 in.dia.)
I 5 mm (0.197 in.)
J 18 mm dia. (0.71 in.dia.)
K 10.6 to 10.7 mm dia. (0.417 to 0.421 in.dia.)
L 7 mm (0.276 in.)
C1 Chamfer 1.0 mm (0.039 in.)
C2 Chamfer 2.0 mm (0.079 in.)
C0.3 Chamfer 0.3 mm (0.012 in.)

Bushing Replacing Tools

Application: Use to press out and to press fit the bushing.
1. For small end bushing
A 145 mm (5.71 in.)
B 20 mm (0.79 in.)
C 100 mm (3.94 in.)
D 19.90 to 19.95 mm (0.7835 to 0.7854 in.)
E 21.90 to 21.95 mm dia. (0.8622 to 0.8642 in. dia.)
F 25 mm (0.98 in.)
a 6.3 µm (250 µin.)
b 6.3 µm (250 µin.)

2. For idle gear bushing

A 150 mm (5.91 in.)
B 20 mm (0.79 in.)
C 100 mm (3.94 in.)
D 19.90 to 19.95 mm (0.7835 to 0.7854 in.)
E 21.90 to 21.95 mm dia. (0.8622 to 0.8642 in. dia.)
F 25 mm (0.98 in.)
a 6.3 µm (250 µin.)
b 6.3 µm (250 µin.)
W1025500
Flywheel Stopper
Application: Use to loosen and tighten the flywheel screw.
A 20 mm (0.79 in.)
B 15 mm (0.59 in.)
C 10 mm dia. (0.39 in. dia.)
D 30 mm (1.18 in.)
E 8 mm (0.31 in.)
F 200 mm (7.87 in.)
W10259480

KiSC issued 01, 2006 A

G-23
WG972-E2, DF972-E2, WSM G GENERAL

Crankshaft Bearing 1 Replacing Tool

Application: Use to press out and press fit the crankshaft bearing 1.
[Press Out]
A 135 mm (5.31 in.)
B 72 mm (2.83 in.)
C 40 mm radius (1.57 in. radius)
D 10 mm (0.39 in.)
E 22 mm (0.87 in.)
F 20 mm dia. (0.79 in. dia.)
G 47.90 to 47.95 mm dia. (1.8858 to 1.8878 in. dia.)
H 43.90 to 43.95 mm dia. (1.7283 to 1.7303 in. dia.)

[Press Fit]
A 130 mm (5.12 in.)
B 72 mm (2.83 in.)
C 40 mm radius (1.57 in. radius)
D 9 mm (0.35 in.)
E 24 mm (0.95 in.)
F 20 mm (0.79 in.)
G 68 mm dia. (2.68 in. dia.)
H 43.90 to 43.95 mm dia. (1.7283 to 1.7303 in. dia.)
W1026139
Valve Stem Seal Replacing Tool
Application: Use to press fit the valve stem seal.
A 17.5 mm dia. (0.6890 in. dia.)
B 13.7 to 13.9 mm dia. (0.5394 to 0.5472 in. dia.)
C 11.0 to 11.2 mm dia. (0.4331 to 0.4409 in. dia.)
D 75 mm (2.9528 in.)
E 60 mm (2.3622 in.)
F 45 mm (1.7717 in.)
G 11.5 to 11.6 mm (0.4528 to 0.4567 in.)
H 8.5 mm (0.3346 in.)
I 37.5 mm (1.4764 in.)
J 6 mm dia. (0.2362 in. dia.)
K 6 mm dia. (0.2362 in. dia.)
L R 30
M 26 mm dia. (1.0236 in. dia.)
a Chamfer 0.3 mm (0.012 in.)
b Chamfer 0.4 mm (0.016 in.)
c Chamfer 0.2 mm (0.0079 in.)
W1041815

KiSC issued 01, 2006 A

G-24
WG972-E2, DF972-E2, WSM G GENERAL

Electronic Governor Service Tool

■ NOTE
• Many applications are delivered pre-configured, calibrated,
and tuned. These units do not require the use of the Service
Tool.
The Service Tool software is used to troubleshoot the electronic
governor.
The Service Tool software resides on a PC (Personal computer)
and communicates to the electronic governor through connector
pins 4 and 6. An external RS-232 transceiver is necessary to make
communications possible with the Woodward L-Series Service Tool.

The following hardware is required to work with the L-Series

control:
communication port, and Windows 95 / 98 / 2000 / NT / Me / XP as
the operating system.
• PC-compatible laptop or desktop computer with at least one
available serial communications port, and Windows 95 / 98 /
2000 / NT / Me / XP as the operating system.
• Datalink harness
A connectivity kit (Woodward No. 8923-1061) can be purchased
from Woodward to accomplish this.

In addition to the hardware, the following are the distributions of

tool software needed to communicate with the control:
• Woodward part number 9927-1222, L-Series Service Tool.

CAUTION
• There is a potential for serial port damage when
communicating with the L-Series control. This is caused by
a difference in AC voltage between neutral and earth ground.
If the PC RS-232 port ground is referenced to AC neutral, and
the L-Series control is referenced to battery ground (AC
earth ground), a large amount of current can be experienced.
To avoid this situation, we strongly recommend placing an
isolation transformer between the AC outlet and the PC.
(1) Connectivity Kit A : To Actuator
B : From Engine Control Harness
C : To Personal Computor

W10563620

KiSC issued 01, 2006 A

G-25
 MECHANISM

CONTENTS

1. FEATURE ........................................................................................................ M-1

2. ENGINE BODY ............................................................................................... M-2
[1] CYLINDER BLOCK................................................................................... M-2
[2] HALF-FLOATING HEAD COVER ............................................................ M-2
[3] CYLINDER HEAD ..................................................................................... M-3
[4] CRANKSHAFT........................................................................................... M-3
[5] PISTON AND PISTON RING.................................................................. M-4
[6] OIL PAN .................................................................................................... M-5
[7] CONNECTING ROD ................................................................................. M-5
[8] CAMSHAFT ............................................................................................... M-5
[9] FUEL CAMSHAFT .................................................................................... M-6
[10]ROCKER ARM ASSEMBLY .................................................................... M-6
[11]INLET AND EXHAUST VALVES ............................................................ M-6
[12]FLYWHEEL................................................................................................ M-7
[13]CLOSED BREATHER............................................................................... M-7
3. LUBRICATING SYSTEM ................................................................................ M-8
[1] GENERAL .................................................................................................. M-8
[2] OIL PUMP ................................................................................................. M-9
[3] RELIEF VALVE ......................................................................................... M-9
[4] OIL FILTER CARTRIDGE........................................................................ M-9
[5] OIL PRESSURE SWITCH ..................................................................... M-10
4. COOLING SYSTEM ...................................................................................... M-11
[1] GENERAL ................................................................................................ M-11
[2] COOLING FIN......................................................................................... M-11
[3] WATER PUMP........................................................................................ M-11
[4] THERMOSTAT ........................................................................................ M-12
[5] RADIATOR............................................................................................... M-12
[6] RADIATOR CAP ..................................................................................... M-13
[7] VAPORIZER (DF972-E2)........................................................................ M-13
5. FUEL SYSTEM ............................................................................................. M-14
[1] GENERAL ................................................................................................ M-14
[2] CARBURETOR (WG972-E2).................................................................. M-15
[3] DF CARBURETOR (DF972-E2) ............................................................ M-16
[4] VAPORIZER (DF972-E2)........................................................................ M-17
[5] GOVERNOR ............................................................................................ M-20
[6] INLET MANIFOLD .................................................................................. M-21
[7] FUEL FILTER (FOR GASOLINE LINE) ............................................... M-21
[8] ELECTRO MAGNETIC FUEL FEED PUMP (FOR GASOLINE LINE) M-21
6. IGNITION SYSTEM ...................................................................................... M-22
[1] DEGITAL IGNITION SYSTEM ............................................................... M-22
7. ELECTRICAL SYSTEM ................................................................................ M-23
[1] STARTING SYSTEM .............................................................................. M-23
[2] CHARGING SYSTEM ............................................................................. M-24
[3] SOLENOID............................................................................................... M-28
8. ELECTRONIC GOVERNOR ......................................................................... M-29

KiSC issued 01, 2006 A

WG972-E2, DF972-E2, WSM GASOLINE / LPG ENGINE

1. FEATURE

In 2003, Kubota added two new compact diesel engines, Z602 and D902, to its SUPER MINI Series. WG/DF972
is two dual fuel (gasoline / LP Gas) type engine that is solidly on this world acclaimed diesel engine series.
Based on the new D902, the new WG / DF972 is exceptionally well made with such features as high power density,
tough reliability, lower noise / vibration, and a special SI combustion chamber. To simplify maintenance, most engine
parts are interchangeable with their diesel counterparts.
The new WG/DF engines will meet and beat the toughest industrial challenges.
WG972-E2 ; This is a gasoline engine.
DF972-E2 ; This is a Dual Fuel (gasoline / LPG) engine.
(-E) model was developed with an eye toward clean exhaust gas which is more environmentally friendly.

Kubota's outstanding technology enables these engines to meet all current existing emission regulations around
the world including Tier 2 emission regulations of both EPA and CARB LSI (under 1 liter).

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2. ENGINE BODY
[1] CYLINDER BLOCK
The engine has a high durability tunnel-type cylinder
block in which the crank bearing component is a
constructed body. Furthermore, liner less type, allow
effective cooling, less distortion, and greater
wearresistance. The noise level is reduced to a minimum
because each cylinder has its own chamber.
To increase the rigidity of the cylinder block, parts of
engine block which support main bearing case has
thicker rib for additional rigidness to improve noise and
vibration.
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[2] HALF-FLOATING HEAD COVER

The rubber packing is fitting in to maintain the head
cover 0.5 mm or so off the cylinder head. This
arrangement helps reduce noise coming from the
cylinder head.
(1) Cylinder Head Cover (2) Rubber Packing
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[3] CYLINDER HEAD

■ Intake and Exhaust Port

The cross-flow type intake / exhaust ports, which

lower the heat conduction from the exhaust port to the
intake port. The low heat conduction keeps the intake air
from being heated and expanded by the exhaust gas.
(1) Intake Port (2) Exhaust Port
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■ Combustion System
The Spark lgnition type combustion chamber,
compactly placed on top of the piston head, successfully
reduces emissions. To ensure even more reliable
emission life, the intake / exhaust valve seats are fitted
with special heat resistant stellite alloys.
(1) Valve (4) Piston
(2) Valve Seat (5) Spark Plug
(3) Main Combustion Chamber
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[4] CRANKSHAFT
The crankshaft with the connecting rod converts the
reciprocating motion of the piston into rotating motion.
The crankshaft (2) has oil passages drilled so that oil can
flow from the main bearings to the crank pin bearings.
The front journal is supported by a sleeve type
bearing (crankshaft bearing 1) (1), the intermediate
journal by a split type (crankshaft bearing 3) (4), and the
rear by a split type (crankshaft bearing 2) (6) with thrust
bearings (5).
(1) Crankshaft Bearing 1 (4) Crankshaft Bearing 3
(2) Crankshaft (5) Thrust Bearing
(3) Feather Key (6) Crankshaft Bearing 2
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[5] PISTON AND PISTON RING

■ Piston
Expansion Control Piston:
The thermal expansion is suppressed to the minimum
by the adoption of the strut (5). The piston head has the
combustion chamber (1) with the concave of bathtub
shaped type.

■ Piston Ring
Top Ring:
Barrel-faced type has an ideal shape in terms of
lubrication theory in order to prevent abnormal wear due
to edge loading at the time of initial running-in, and it is
very effective in prevention of blow-by.

Second Ring:
Barrel-faced type has an ideal shape in terms of
lubrication theory in order to prevent abnormal wear due
to edge loading at the time of initial running-in, and it is
very effective in prevention of blow-by.

Oil Ring:
Oil ring consists of three steel components, that is
upper and lower rails and one spacer being held between
two rails. This function is particularly effective in
preventing oil-up because of high boost at the time of
engine coasting.
(1) Combustion Chamber (4) Oil Ring
(2) Top Ring (5) Strut
(3) Second Ring
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■ Piston Skirt
Piston's skirt is coated with molybdenum isulfide ★,
which reduces the piston slap noise and thus the entire
operating noise.

★ Molybdenum disulfide (MoS2)

The molybdenum disulfide serves as a solid lubricant,
like a Graphite or Teflon. This material helps resist metal
wears even with little lube oil.
(1) Molybdenum Disulfide
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[6] OIL PAN

The oil pan is expanded under the gear case.
Therefore, the height of the engine can be lowered more
than so far while securing a necessary amount of oil.
(1) Gear Case (3) Crank Case
(2) Oil Pan
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[7] CONNECTING ROD

The connecting rod (2) is used to connect the piston
with the crankshaft. The big end of the connecting rod
has a crankpin bearing (3) (split type) and the small end
has a small end bushing (1) (solid type).
(1) Small End Bushing (4) Connecting Rod Cap
(2) Connecting Rod (5) Connecting Rod Screw
(3) Crankpin Bearing

[8] CAMSHAFT
The camshaft (1) is made of special cast iron, and the
journal and cam sections are chilled to resist wear.
The cams on the camshaft cause the intake and
exhaust valves to open as the camshaft rotates. The
bearing and journals are force-lubricated.
(1) Camshaft (3) Camshaft Stopper
(2) Feather Key (4) Cam Gear

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[9] FUEL CAMSHAFT

The camshaft (10) is equipped with steel ball (2) to
control the governor..
Power can be taken out from this shaft. (Side PTO).
(1) Injection Pump Gear (7) Stopper
(2) Steel Ball (8) Ball Bearing
(3) Governor Sleeve (9) Feather key
(4) Steel Ball (10) Fuel Camshaft
(5) Governor Ball Case (11) Ball Bearing
(6) Governor Sleeve Snap Ring

[10] ROCKER ARM ASSEMBLY

The rocker arm assembly includes the rocker arms
(2) and adjusting screws (1), the end of which rests on
the push rods, rocker arm brackets (4) and rocker arm
shaft (3).
The rocker arms swing and transmits the
reciprocating motion of the push rods to the inlet and
exhaust valves to open and close them.
(1) Adjusting Screw (3) Rocker Arm Shaft
(2) Rocker Arm (4) Rocker Arm Bracket

[11] INLET AND EXHAUST VALVES

The valve and its guide for the inlet are different from
those for the exhaust.
Other parts, such as the spring (4), spring retainer (3),
collet (2), stem seal (5), and cap (1) are the same for both
the inlet and exhaust.
(1) Valve Cap (5) Stem Seal
(2) Collet (6) Valve Guide
(3) Spring Retainer (7) Inlet Valve
(4) Spring (8) Exhaust Valve

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[12] FLYWHEEL
The flywheel (2) is connected with the crankshaft (1),
it stores the rotaing force in the combustion stroke as
inertial energy to rotate the crankshaft smoothly.
The flywheel periphery is provided with marks
showing fuel injection timing and top dead center.
The flywheel has gear teeth around its outer rim,
which mesh with the drive pinion of the starter.
(1) Crankshaft (3) Flywheel Mounting Screw
(2) Flywheel

[13] CLOSED BREATHER

Blow-by gas (1) from crankcase is deoiled in the
breather assembly (2) and sends to the air cleaner flange
(3) where the blow-by gas (1) is mixed with the intake air
(4).
(1) Blow-by Gas (4) Intake Air
(2) Breather Assembly (5) Breather Hose
(3) Air Cleaner Flange

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3. LUBRICATING SYSTEM
[1] GENERAL

The lubricating system consists of an oil strainer, an oil pump, a relief valve, an oil filter cartridge and an oil pressure
switch. The oil pump sucks the lubricating oil in the oil pan through the strainer and sends it to the oil filter cartridge,
where the oil is further filtered.
The filtered oil is forced to the crankshaft, the connecting rods, the idle gear, the camshaft and the rocker arm shaft
through the oil passage in the cylinder block and the shafts to lubricate the bearings.
Some oil, splashed by the crankshaft or thrown off from the bearings, lubricates other engine parts: the pistons,
the cylinder walls, the piston pins, the tappets, the push rods,the timing gears, and the inlet and exhaust valves.

(A) Piston (C) Camshaft (E) Oil Strainer (F) Oil Pump
(B) Rocker Arm and Rocker Arm (D) Oil Filter Cartridge and
Shaft Relief Valve

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[2] OIL PUMP

The oil pump is a trochoid pump, whose rotors have
trochoid lobes. The inner rotor (3) has 4 lobes and the
outer rotor (4) has 5 lobes, and they are eccentrically
engaged with each other. The inner rotor, which is driven
by the crankshaft through the gears, rotates the outer
rotor in the same direction, varying the space between
the lobes.
While the rotors rotate from (A) to (B) , the space
leading to the inlet port increases, which causes the
vacuum to suck in the oil from the inlet port.
When the rotors rotate to (C) , the space between
both rotors switches from the inlet port to the outlet port.
At (D) , the space decreases and the sucked oil is
discharged from the outlet port.
(1) Inlet Port (3) Inner Rotor
(2) Outlet Port (4) Outer Rotor
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[3] RELIEF VALVE

The relief valve prevents the damage to the
lubricating system due to the high pressure of the oil.
This relief valve is a ball direct acting type, and is best
suited for low pressures.
When the pressure of the oil, forced by the pump,
exceeds the specified value, the oil pushes back the ball
(2) and escapes to the oil pan.
(1) Spring (3) Valve Seat
(2) Ball

[4] OIL FILTER CARTRIDGE

After lubricating, the lubricating oil brings back
various particles of grit and dirt to the oil pan. Those
particles and the impurities in the lubricating oil can
cause wear or seizure of the engine parts. It may also
impair the physical and chemical properties of the oil
itself.
The lubricating oil which is force-fed by the pump, is
filtered by the filter cartridge with the filter element (2).
When the filter element accumulates on excessive
amount of dirt and the oil pressure in the inlet line builds
up by 98 kPa (1.0 kgf/cm2, 14 psi) more than the outlet
line, the bypass valve (1) opens to allow the oil to flow
from the inlet into the outlet line, bypassing the filter
element.
(1) Bypass Valve (2) Filter Element

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[5] OIL PRESSURE SWITCH

The oil pressure switch is mounted on the cylinder
block and is led to the lubricating oil passage.
When the oil pressure falls below the specified value,
the oil pressure warning lamp lights.
(1) Terminal [A] At the proper oil pressure
(2) Insulator [B] At lower oil pressure, 49
(3) Spring kpa (0.5kgf/cm2, 7 psi) or
(4) Rubber Gasket less
(5) Contact Rivet
(6) Contact
(7) Oil Switch Body

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4. COOLING SYSTEM
[1] GENERAL
The cooling system consists of a radiator (1), a
centrifugal water pump (4), a suction fan (2) and a
thermostat (3).
The coolant is cooled through the radiator core, and
the fan behind the radiator pulls the cooling air through
the core to improve cooling.
The water pump sucks the coolant from the radiator
or from the cylinder head and forces it into the cylinder
block.
The thermostat opens or closes according to the
coolant temperature, to allow the coolant to flow from the
cylinder block to the radiator while open, or only to the
water pump while closed.
Thermostat's valve Factory 69.5 to 72.5 C°
opening temperature spec. 157.1 to 162.5 F°

(1) Radiator (4) Water Pump

(2) Cooling Fan (5) Cylinder Head
(3) Thermostat (6) Cylinder Block
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[2] COOLING FIN

The cooling fin is set up around the oil passage in the
gear case.
Therefore, the temperature of oil is decreased by the
wind generated by the cooling fan.
(1) Cooling Fin
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[3] WATER PUMP

The water pump is driven by the crankshaft and a V
belt. The rotating impeller (4) in the water pump sucks
the coolant from the radiator and sends it into the water
jacket in the cylinder block.
The mechanical seal (3) prevents the water from
entering the bearing unit (1).
(1) Bearing Unit (3) Mechanical Seal
(2) Water Pump Body (4) Water Pump Impeller

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[4] THERMOSTAT
The thermostat is of the wax pellet type.
The thermostat controls the flow of the coolant to the
radiator to keep the proper temperature.
The case (1), which serves as a valve seat (1), has a
spindle inserted in the pellet (3) which is installed to the
valve (2). The spindle is covered with the synthetic
rubber (5) in the pellet.
The wax is charged between the pellet and the rubber.
■ At low temperature (lower than 71 °C)
The valve (2) is seated by the spring (7) and the
coolant circulates in the engine through the water return
hose without running into the radiator.
Only the air in the water jacket escapes to the radiator
through the leak hole (8) of the thermostat.
■ At high temperature (higher than 85 °C)
As the coolant temperature rises, the wax in the pellet
(3) turns liquid and expands, repelling the spindle, which
causes the pellet to lower.
The valve (2) opens to send the coolant to the radiator.
(1) Seat (6) Wax (Solid)
(2) Valve (7) Spring
(3) Pellet (8) Leak Hole
(4) Spindle (9) Wax (liquid)
(5) Synthetic Rubber
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[5] RADIATOR
The radiator core consists of coolant carrying tubes
(1) and fins (2) meeting at a right angle with the tubes.
The fin is a louverless, corrugated type which is light in
weight, high in heat exchange ratio and less apt to clog.
The coolant in the tubes is cooled by the air flowing
through the tube walls and fins.
(1) Tube A : Cooling Air
(2) Fin

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[6] RADIATOR CAP

The pressure type radiator cap prevents differences
in pressure between the inside and the outside of the
radiator from deforming the radiator.
When the coolant temperature rises and the pressure
in the radiator increases above the specified pressure,
the pressure valve (1) opens to reduce the internal
pressure.
When the coolant temperature falls and a vacuum
forms in the radiator, the vacuum valve (2) opens to
introduce the air into the radiator.
(1) Pressure Valve (Opening (2) Vacuum Valve
pressure 88 kPa (0.9 kgf/cm2,
13 psi))

[7] VAPORIZER (DF972-E2)

When evaporating by primary chamber of vaporizer
liquid LPG needs the evaporation heat.
This vaporizer installs the water jacket, throws the
coolant of engine, heats primary chamber, promotes
evaporation, and prevents valves being frozen.
(1) Vaporizer (3) Hot Coolant Out
(2) Hot Coolant In

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5. FUEL SYSTEM
[1] GENERAL

(1) Gasoline Tank* (9) Vapor Hose* (a) Gasoline Line [A] WG972-E2
(2) Gasoline Cock* (10) Vaporizer / Regulator (b) Gaseous Propane Line [B] DF972-E2
(3) Fuel Filter (11) LPG Shut Off Valve* (c) Liquid Propane Line
(4) Fuel Feed Pump (12) LPG Filter* (d) Hot Coolant Out Line
(5) Gasoline Cut Off Solenoid (13) LPG Manual Valve* (e) Hot Coolant In Line Component Marked * Is Not
(6) Carburetor (14) LPG Tank* (f) Vacuum Line Provided by KUBOTA
(7) DF Carburetor (15) Water Hose*
(8) LPG Cut Off Solenoid (16) Vacuum Hose*

WG972-E2:
The fuel is fed from the fuel tank (1) through the fuel filter (3) to the carburetor (6) by the fuel feed pump (4).
DF972-E2:
This fuel system has 2 ways. Gasoline fuel is the same as WG972-E2.
For LPG fuel, the liquid fuel stored in the LPG tank (4) is sent to vaporizer (10) by pressure in the gaseous phase
in the tank through the fuel filter (12) and shut off valve (11).
The liquid fuel is evaporated in vaporizer and is sent to the DF Carburetor (7) as a gaseous fuel of gas pressure
near the atmospheric pressure. The DF carburetor (7) mixes the gas and air is supplied in the cylinder.

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[2] CARBURETOR (WG972-E2)

(1) Choke Lever
(2) Venturi
(3) Throttle Shaft
(4) Main Air Jet
(5) Throttle Valve
(6) Main Nozzle
(7) Bleeder Hole
(8) Float Chamber Gasket
(9) Float
(10) Float Chamber
(11) Jet Holder
(12) Solenoid Valve Assembly
(13) Earth Cord
(14) Float Pin
(15) Needle Valve
(16) Valve Seat
(17) Inlet Port
(18) Choke Valve
(19) Carburetor Body
(20) Main Jet
(21) Pilot Outlet
(22) Throttle Stopper Adjusting
Screw
(23) Pilot Screw
(24) Pilot Jet
(25) Pilot Air Jet
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Designed for general purpose use, this carburetor provides engines with the ideal fuel-air mixture for all speed
ranges.
1) Float Chamber
When the gasoline in the fuel tank flows into the float chamber (10), the float (9) rises and, when a predetermined
amount of gasoline is in the chamber, it pushes the needle valve (15) against the valve seat (16) to stop additional
gasoline from entering through the inlet port (17). As the gasoline is consumed, the float goes down and more gasoline
is led into the chamber to maintain a constant distance between the main nozzle (6) and the level of the gasoline.
2) Starting System
To start an engine in cold weather, the fuel-air mixture must be richer than normal. A choke valve (18) controlled
by the choke lever (1) is provided to enrich the mixture.
As the choke valve is closed, the air supply is restricted to make the mixture rich. This rich mixture is then supplied
to the intake manifold to facilitate starting.
3) Slow System
When the throttle valve (5) closes, air that flows into the cylinder passes along the valve at a high speed. As a
result, a negative pressure is crated in the pilot outlet (21) which has an outlet port in the inner wall. This causes
gasoline in the main nozzle (6) to flow through the pilot jet (24) to be sucked into the cylinder. Air that enters from the
pilot air jet (25) is mixed with gasoline in the pilot jet (24), atomized in an appropriate condition, sprayed from the pilot
outlet (21) and sucked into the cylinder through the main passage. The slow speed of the engine is controlled by
changing the jet area with the pilot jet (24).
4) Main Carburetor System
The speed of air that flows into the cylinder increases when it passes the venturi (2), and the negative pressure
increase as a result at the tip of the main nozzle (6). The negative pressure causes the gasoline in the float chamber
(10) to flow through the main jet (20) and to be sucked into the main nozzle (6). Air which flows from the main air jet
(4) into the bleeder hole (7) of the main nozzle (6) is mixed with gasoline, atomized in an appropriate condition, then
sprayed from the nozzle tip to the venturi (2) and sucked with the main air into the cylinder.

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[3] DF CARBURETOR (DF972-E2) ■ NOTE

• DF Carburetor operates the same as a gasoline
carburetor in gasoline fuel.
With the fuel select switch (8) in the "GASOLINE"
position (D) and the main switch in the "ON" position, the
battery current flows to the gasoline cut off solenoid (6).
Therefore gasoline fuel in the float chamber flows to the
mixing chamber.
When the fuel select switch (8) is turned to the "LPG"
position (E), the battery current stops to the gasoline cut
off solenoid (6) and flows to the LPG cut off solenoid (3)
and LPG shut off solenoid valve (9).
Then, the gasoline fuel flow is shut and LPG fuel flows
to the mixing chamber.
The mixer meters both fuel and air, and procedures
an air / fuel mixture that has the proper ratio as required
by the engine.
When the engine starts, the LPG furl flows out from
main jet (4) to venture a constant amount and is mixed
with air quantity corresponding to the opening of the
throttle valve (1) and is supplied to the cylinder.
When the main switch (7) turned to the "OFF"
position, the battery current stops to the both of
solenoids.
Then, both gasoline fuel and LPG fuel can not flow to
the mixing chamber.
(1) Choke Valve A: Air
(2) Throttle Valve B: LPG Fuel (gaseous)
(3) LPG Cut Off Solenoid C: Mixture (Air / Fuel)
(4) LPG Main Jet D: Gasoline Position
(5) Gasoline Main Jet E: LPG Position
(6) Gasoline Cut Off Solenoid
(7) Main Switch
(8) Fuel Select Switch
(9) LPG Shut Off Solenoid Valve

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[4] VAPORIZER (DF972-E2)

Vaporizer is a device which converts the liquid fuel
into the gaseous fuel and the following structures and
functions are possessed.
■ Primary Chamber
The liquid fuel is decompressed (the first
decompression) and it is evaporated.

■ Secondary Chamber
The fuel which flows in is decompressed from the
primary chamber to the vicinity of the atmospheric
pressure further (the second decompression).

■ Water Passage
The coolant of the engine is made to circulate as a
heat source to evaporate the LPG.

■ Vacuum Lock Chamber

When the engine stops, the fuel from primary
chamber is prevented from flowing out.
(1) Secondary Chamber (3) Primary Chamber
(2) Water Passage (4) Vacuum Lock Chamber
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■ Primary Chamber
The liquid fuel which pushes the primary valve (6)
open passes between the valve and the valve seat (7),
enters primary chamber (1), and decompresses and is
evaporated.
When the inflow of the fuel continues and the primary
chamber pressure rises more than the specified
pressure 32.7 kPa (0.3 kgf/cm2, 4.3 psi), the tension in
the diaphragm spring (3) is overcome and do the push up
of primary diaphragm (4).
At this time, do the push up of primary valve lever
spring (2) of primary valve lever (5), primary valve (6) is
shut, and the inflow of the fuel is intercepted.
The tension in the diaphragm spring (3) grows more
than the primary chamber pressure when the fuel is
consumed and the primary chamber pressure lowers
more than a regulated value and a primary diaphragm is
depressed below.
The primary valve lever (5) is depressed at the same
time.
A primary valve opens and the fuel flows in again.
When the diaphragm tears by any chance and the
fuel flows in the primary diaphragm spring side, the
primary diaphragm spring side is connected with second
chamber in the balance passage so that the fuel should
not flow out outside.
(1) Primary Chamber (5) Primary Valve Lever
(2) Primary Valve Lever Spring (6) Primary Valve
(3) Primary Diaphragm Spring (7) Valve Seat
(4) Primary Diaphragm
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■ Secondary Chamber
The fuel adjusted with primary chamber to the
specified pressure enters secondary chamber (5)
between secondary valve (1) and the valve seat (2) and
is decompressed to the vicinity of the atmospheric
pressure almost.
A secondary valve is assembled to a part of the
secondary valve lever (3) supported to body and is shut
by the tension of the spring of a secondary valve spring
(4).
A secondary diaphragm pin (6) touches the edge
besides this lever (3).
The one side of secondary diaphragm (8) is faced in
secondary chamber and the other side faces
atmosphere chamber (10).
When the engine stops, the atmospheric pressure is
led in secondary chamber and a secondary valve is shut
by the tension of a secondary valve spring.
When the engine rotates, the negative pressure is
generated in the venturi tube of the mixer.
As for this negative pressure, working secondary
diaphragm (8) is pulled to the second chamber side by
the difference pressure with atmosphere chamber by
second chamber.
Do the push up of the secondary valve lever (3) by
this working, secondary valve is opened, and the fuel
flows in.
When pressure in chamber rises by the fuel which
flows in, the diaphragm is pushed to the atmosphere
chamber side and narrows the opening of the valve and
decreases the supply of the fuel.
Secondary chamber is almost maintained in the
atmospheric pressure by the thing to repeat such
working.
(1) Secondary Valve (6) Diaphragm Pin
(2) Valve Seat (7) Balance Spring
(3) Secondary Valve Lever (8) Secondary Diaphragm
(4) Secondary Valve Lever (9) Balance Lever Spring
Spring (10) Atmosphere Chamber
(5) Secondary Chamber (11) Idle Adjust Screw
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■ Vacuum Lock Chamber

1) Operation when engine stops
Because pressure on the vacuum lock chamber (3)
side and the secondary chamber (4) side is equal,
vacuum lock diaphragm (5) is pushed to the second
chamber side by the tension of vacuum lock diaphragm
spring (2).
Secondary valve and the seat are made to close as
vacuum lock diaphragm pin (6) pushes secondary valve
lever (7) and the fuel leakage is prevented.

2) Operation at engine starting

The negative pressure is caused in inlet manifold at
the same time as the cranking's beginning.
This negative pressure acts in vacuum lock chamber
(3) and vacuum lock diaphragm (5) is drawn to the
vacuum lock chamber side.
As a result, the movement of secondary valve lever
(7) becomes free and the fuel inflow adjustment due to
secondary valve (1) becomes possible.
The negative pressure in inlet manifold always works
while the engine is rotating and the movement of
secondary valve lever is tuned to the movement of
secondary diaphragm.
(1) Secondary Valve (5) Vacuum Lock Diaphragm
(2) Vacuum Lock Diaphragm (6) Diaphragm Pin
Spring (7) Secondary Valve Lever
(3) Vacuum Lock Chamber
(4) Secondary Chamber

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WG972-E2, DF972-E2, WSM GASOLINE / LPG ENGINE

[5] GOVERNOR
The engine is equipped with a centrifugal ball
mechanical governor which activates the throttle in
response to engine speed.
When the engine is carrying a load and running at
rated speed, the speed will drop if the load is increased
even slightly. In this case, the governor automatically
opens the throttle valve of the carburetor to maintain the
original speed.
Dumping the load suddenly will cause a rapid
increase in speed. In this case, the governor
automatically moves the throttle valve in closing direction
to prevent the engine from increasing its speed.
1) When engine is carrying a load and running at
rated speed
When there is no change in load, the centrifugal force
of the ball (6) which is attached to the governor gear (4)
balances with the tensile force of the governor spring (8)
via governor sleeve (5), fork lever (7), governor lever
shaft (3) and governor lever (2). The engine speed and
output are thus kept constant.
2) When load is applied to engine
When the load is applied to the engine running at
rated speed, the speed of the governor gear (4) which is
connected to the idle gear decreases. As a result, the
centrifugal force of the ball (6) becomes smaller. The
tensile force of the spring (8) overcomes the centrifugal
force, and the governor lever (2) causes the throttle lever
(1) to move in the open direction (B). The original engine
speed is thus maintained.
3) When load is dumped
When the load is dumped suddenly, the centrifugal
force of the ball (6) overcomes the tensile force of the
spring (8). As a result, the governor lever (2) causes the
throttle lever (1) to move in the shut direction (A) and
prevents the engine from increasing its speed.
(1) Throttle Lever (8) Governor Spring
(2) Governor Lever (9) Speed Control Lever
(3) Governor Lever Shaft (10) Carburetor / DF Carburetor
(4) Governor Gear
(5) Governor Sleeve
(6) Ball A : Shut Direction
(7) Fork Lever B : Open Direction
W1014969

KiSC issued 01, 2006 A

M-20
WG972-E2, DF972-E2, WSM GASOLINE / LPG ENGINE

[6] INLET MANIFOLD

Part of coolant heated in the water jacket is
channeled to the inlet manifold, where the hot coolant
heats the fuel-air mixture for better carburetion. Heating
effect is particularly good when the engine is running at
low speeds and with light load is cold weather, thus
improving fuel economy and acceleration.
(1) Intake Manifold

[7] FUEL FILTER (FOR GASOLINE LINE)

The fuel filter is installed in the fuel line between the
fuel tank and the feed pump.
As the fuel flows from the inlet (A) through the filter
element (1), the dirt and impurities in the fuel are filtered,
allowing only clean fuel to penetrate the inside of the filter
element. The cleaned fuel flows out from the outlet (B).
Type of filter element Accordion-pleated paper type
Material of filter element Cotton fiber
Filter mesh 15 µm (0.00059 in.)

(1) Filter Element A : Inlet

B : Outlet

[8] ELECTRO MAGNETIC FUEL FEED PUMP (FOR GASOLINE LINE)

An electro magnetic pump uses a transistor that
causes the pump to start pumping fuel when the engine
is switched on.
Therefore, fuel is supplied to the carburetor
regardless of engine speed. This pump is driven by the
battery. It can therefore be operated even with the
engine being stopped.

KiSC issued 01, 2006 A

M-21
WG972-E2, DF972-E2, WSM GASOLINE / LPG ENGINE

6. IGNITION SYSTEM
[1] DEGITAL IGNITION SYSTEM
■ General
The function of an ignition system is to provide the
electrical spark that ignites the air/fuel mixture in the
cylinder at precisely the correct time.
For this purpose, the pick-up sensor (3) detects
voltage waveform according to the shape of the rotor (2)
that is built into the flywheel (1). The voltage waveform
signal is fed to the igniter (4), in which the signal is
converted by a microprocessor to the angular and rpm
data that corresponds to each cylinder. Based on this
information, an optimum timing is figured out by the
microprocessor to cut off the current that flows to the
ignition coil (5) of each cylinder. The duration of current
flowing to the ignition coil (5) is also controlled. In this
way, a high voltage is generated at the secondary
winding of the ignition coil (5), which activates the spark
plug (6).
Without any mechanical contact, the ignition system
is digitally microprocessor-controlled for greater
reliability and higher precision.
• Control at ignition time :
The ignition time is controlled according to the
engine speed.
• Control at energizing time :
The energizing time of the ignition coil is controlled
according to the engine speed.
• Lock prevention :
Intercept the current of the coil for the damage
prevention of the coil when the ignition switch is
energized to the coil as turning on.
• Lock prevention :
Intercept the current of the coil for the damage
prevention of the coil when the ignition switch is
energized to the coil as turning on.
(1) Flywheel (4) Ignitor
(2) Rotor (5) Ignition Coil
(3) Pick-up Sensor (6) Spark Plug
W1014569

KiSC issued 01, 2006 A

M-22
WG972-E2, DF972-E2, WSM GASOLINE / LPG ENGINE

7. ELECTRICAL SYSTEM
[1] STARTING SYSTEM
■ Staeter
The starter is the electromagnetic drive type.
DC, Series-wound, Electromagnetic
Type of motor
drive
Nominal output 12V
Nominal output 1.0 kW
30 seconds (Do not rotate continuously
Nominal output
for longer periods.)
Direction of rotation Clockwise as viewed fromo pinion side

(1) Solenoid Switch (6) Commutator

(2) Plunger (7) Armature
(3) Spring (8) Field Coil
(4) Shift Lever (9) Overrunning Clutch
(5) Brush
W1017019

■ Operation of Starter
[ When key switch is turned to "START" position]
The contacts of key switch (1) close and the holding
coil (3) is connected to the battery to pull the plunger (5).
The pull-in coil (4) and the starting motor are also
connected to the battery.
The pinion (8) is pushed against the ring gear (9) with
the overrunning clutch (7) by the shift lever (6) and the
magnetic switch is closed.
[ When the solenoid switch is closed]
The current from the battery flows through the
solenoid switch (2) to the starting motor.
The pinion (8), which is pushed against the ring gear
(9) and rotated along the spline, meshes with the ring
gear to crank the engine.
The engine starts and increases its speed.
While the pinion spins faster than the armature, the
overrunning clutch (7) allows the pinion to spin
independently from the armature.
The pull-in coil (4) is short-circuited through the
solenoid switch (2) and the key switch (1).
[ When the key switch is released]
The current from the battery flows to the holding coil
(3) through the pull-in coil (4) to diminish the magnetism
between them.
The plunger (5) is pushed by the spring to pull in the
pinion.
(1) Key Switch (6) Shift Lever
(2) Solenoid Switch (7) Overrunning Clutch
(3) Holding Coil (8) Pinion
(4) Pull-in Coil (9) Ring Gear
(5) Plunger
W1017282

KiSC issued 01, 2006 A

M-23
WG972-E2, DF972-E2, WSM GASOLINE / LPG ENGINE

■ Key Switch
The key switch has 4 positions. The terminal "30" is
connected to the battery.
It is released at the "STARTER" position and returns
to the "ON" position.
[START]
When the key is turned to the "START" position,
through the "ON" position the current supplied to the
starter to regulator, oil lamp and accessory
50 to starter
30 from battery
AC to regulator, oil lamp and accessory
[ON]
Only the terminal "AC" is connected to the battery.
At any position of the key except the "OFF" position, the
terminal "AC" is connected to the "30" terminal.
30 from battery
AC to regulator, oil lamp and accessory
W1017536

[2] CHARGING SYSTEM

■ Alternator
This alternator is an 8-8 pole rotating magnet type
generator. It is simple in construction, consisting of a
stator and rotor. The rotor is made up of eight permanent
magnet pole pieces assembled on a shaft and rotates on
the center of the stator around which eight
electromagnetic coils are provided for. This alternator
produces higher voltage in slow speed rotation, and
charges electric current to the battery during engine
idling.
W1017814

KiSC issued 01, 2006 A

M-24
WG972-E2, DF972-E2, WSM GASOLINE / LPG ENGINE

■ Regulator
The regulator performs rectification and voltage
regulation. The regulator converts AC into DC which
flows through the power consuming circuits and the
battery, and also charges the battery. If however, the
battery voltage exceeds a certain level. The DC current
is cut off from the charging circuit to prevent
overcharging.
Model RS5155
Part No. RP201-53710
Weight Approx. 200 g
Regulated voltage 14 to 15 V
Battery to be used 12 V, 28 AH
Charge indication lamp 12 V, 3.4 W
Under 100 V of peak value of no-load
Alternator to be used voltage
Under 16 A of output current

(1) Regulator (6) Blue Lead Wire

(2) Alternator (7) Yellow Lead Wire
(3) Load (8) Red Lead Wire
(4) Charge Lamp (9) Overrunning Clutch
(5) Battery (10) Black Lead Wire
W1015544
■ Features
1. This small-sized regulator can control large output
current because charging current is supplied and
stopped by thyristor (series system).
2. Built-in AC diode generation detecting circuit permits
a charge indication lamp (12 V, 3.4 W) to be easily
connected.
3. Protection diode protects regulator when battery is
wrongly connected.
(1) Blue Lead Wire (4) Green Lead Wire
(2) Yellow Lead Wire (5) Black Lead Wire
(3) Red Lead Wire
W1034000

KiSC issued 01, 2006 A

M-25
WG972-E2, DF972-E2, WSM GASOLINE / LPG ENGINE

■ Charging Machanism
The charging mechanism is described in four
sections:
1. When key switch is "ON".
2. At starting
3. In charging
4. Over-charge protection
(1) GEN: Magnet type AC generator
(2) LAMP: Charge indication lamp (not included in the basic
engine)
(3) KEY SW: Key switch
(4) BATT: Battery (not included in the basic engine)
(5) Blue: GEN connecting terminal
(6) Red: BATT + connecting terminal
(7) Yellow: BATT voltage test terminal
(8) Black: BATT - connecting terminal
(9) Green: LAMP connecting terminal

S1, S2: Output control / rectification thyristor (SCR)

D1, D2: Output rectifying diode
D3, D4: GEN generation detecting diode
D5, D6: Protection diode for wrong connecting of BATT
Z1: BATT terminal voltage setting diode
Q1: GEN generation detecting transistor
Q2: LAMP on / off transistor
Q3: Gate current control transistor
Q4: BATT voltage detecting transistor
W1034331
1. When Key Switch is "ON"
When the engine is at standstill with key switch set at
position 1, the circuit functions to light LAMP, as shown
in figure (A). With key switch at position 1, current flows
to base of Q2 through the route of BATT → emitter / base
of Q2 → R1 → D6 → BATT and collector of Q2 is then
turned on. As a result, current also flows to LAMP
though the route of BATT → emitter / collector of Q2 →
D5 → LAMP → BATT lighting LAMP to indicate that
charging is not carried out. At this time, though current
flows to base of Q3 thorugh the route of BATT → emitter
/ base of Q3 → R2 → D6 → BATT, collector of Q3 has no
current because GEN is stationary.
W1035327
2. At Starting
When key switch is turned to position 2, coil of starter
relay is energized and starter starts engine. GEN also
starts generation for charging and LAMP is turned off.
In detail, with GEN starting, current flows to base of
Q1 through the route of GEN → D1 → emitter / base of
Q1 → R4 → D4 → GEN, or GEN → D2 → emitter / base
of Q1 → R4 → D3 → GEN, and therefore current also
flows through Q1, shortcircuiting emitter and base of Q2.
. As a result, base current of Q2 is interrupted, Q2 is
turned off and accordingly current to LAMP is also
interrupted.
W1035571

KiSC issued 01, 2006 A

M-26
WG972-E2, DF972-E2, WSM GASOLINE / LPG ENGINE

3. In Charging
Because BATT terminal voltage just after engine start
is lower than setting value (14 to 15 V), or lower than
zener level of Z1, current is not supplied to base of Q4
and Q4 is off, as shown in figure (B). Q3 is on with base
current which flows thorugh the route of BATT → emitter
/ base of Q3 → R2 → D6 → BATT, and gate current is
supplied to S1 or S2 through the route of GEN → D1 →
emitter / collector of Q3 → R3 → gate / cathode of S2 →
GEN, or GEN → D2 emitter / collector of Q3 → R3 →
gate / cathode of S1 → GEN.
When engine speed is increased so that GEN
genetration voltage becomes higher than BATT terminal
voltage, S1 or S2 is turned on and, as shown in figure
(C), charge current is supplied to BATT through the route
of GEN → D1 → BATT → anode / cathode of S2 → GEN,
or GEN → D2 → BATT → anode / cathode of S1 → GEN.
After S1 or S2 is turned on, collector current of Q1 and
base current of Q3 are supplied by GEN, not BATT.
When key switch is turned to position 1 after engine is
started, BATT is charged, if BATT terminal voltage is
lower than the setting value, or zener level of Z1.
W1035755
4. Over-Charge Protection
When BATT terminal voltage is higher than the
setting value or zener level of Z1, BATT is not charged
by the function of circuit as shown in figure (D). That is,
Q4 is on with base current which flows through the route
of BATT → emitter / base of Q4 → Z1 → D6 → BATT,
shortcircuiting emitter and base of Q3. Therefore, Q3 is
off with no base current and gate current is not supplied
to S1 and S2. Consequently S1 and S2 are off and BATT
is not charged.
W1036458

KiSC issued 01, 2006 A

M-27
WG972-E2, DF972-E2, WSM GASOLINE / LPG ENGINE

[3] SOLENOID
When the key switch is turned on, a current flows to
the solenoid, which in turn opens the solenoid valve.
When the key switch is turned off, the solenoid valve
closes, blocking the gasoline main jet (2) / LPG main jet
(4).
(1) Gasoline Solenoid Valve [A] WG972-E2
(2) Gasoline Main Jet [B] DF972-E2
(3) LPG Solenoid Valve
(4) LPG Main Jet
W1037289

KiSC issued 01, 2006 A

M-28
WG972-E2, DF972-E2, WSM GASOLINE / LPG ENGINE

8. ELECTRONIC GOVERNOR
Electronic governor combines the electric actuator
with integrated speed control software to control the
speed of the engine. Electronic governor is a
microprocessor-based control that is incorporated into
the actuator, creating a single integrated package. This
eliminates the need for an additional driver box and
speed control box.
(1) Actuator
W1014064

KiSC issued 01, 2006 A

M-29
 SERVICING

CONTENTS

1. TROUBLESHOOTING ......................................................................................S-1
[1] FOR GASOLINE FUEL .............................................................................S-1
[2] FOR LPG FUEL ........................................................................................S-2
[3] FOR ELECTRONIC GOVERNOR ............................................................S-3
2. SERVICING SPECIFICATIONS ......................................................................S-6
3. TIGHTENING TORQUES ..............................................................................S-12
[1] TIGHTENING TORQUES FOR SPECIAL USE SCREWS, BOLTS
AND NUTS...............................................................................................S-12
[2] TIGHTENING TORQUES FOR GENERAL USE SCREWS, BOLTS
AND NUTS...............................................................................................S-13
4. CHECKING, DISASSEMBLING AND SERVICING......................................S-14
[1] CHECKING AND ADJUSTING ...............................................................S-14
(1) Engine Body........................................................................................S-14
(2) Lubricating System .............................................................................S-17
(3) Cooling System...................................................................................S-17
(4) Fuel System ........................................................................................S-20
(5) Ignition System ...................................................................................S-24
(6) Electrical System ................................................................................S-27
(7) Electronic Governor ............................................................................S-31
[2] DISASSEMBLING AND ASSEMBLING..................................................S-32
(1) Draining Coolant and Engine Oil.........................................................S-32
(2) External Components .........................................................................S-33
(3) Cylinder Head, Valves and Oil Pan.....................................................S-37
(4) Thermostat..........................................................................................S-40
(5) Timing Gear, Camshaft and Fuel Camshaft .......................................S-41
(6) Piston and Connecting Rod ................................................................S-43
(7) Crankshaft...........................................................................................S-45
(8) Starter .................................................................................................S-49
[3] SERVICING ..............................................................................................S-50
(1) Cylinder Head and Valves ..................................................................S-50
(2) Timing Gear, Camshaft.......................................................................S-55
(3) Piston and Connecting Rod ................................................................S-58
(4) Crankshaft...........................................................................................S-60
(5) Cylinder ...............................................................................................S-64
(6) Oil Pump .............................................................................................S-65
(7) Starter .................................................................................................S-66

KiSC issued 01, 2006 A

WG972-E2, DF972-E2, WSM GASOLINE / LPG ENGINE

1. TROUBLESHOOTING
[1] FOR GASOLINE FUEL
Reference
Symptom Probable Cause Solution
Page
Engine Will Not Turn Engine jammed Check engine to find –
Over the problem and
repair it
Battery discharged Charge –
Starter malfunctioning Repair or replace S-27
Wires disconnected Reconnect –
Engine Turns Over Increased resistance of moving parts Repair or replace –
Slowly but Does Not Excessively high viscosity engine oil at low Use specified engine G-8
Start temperature oil
Engine Turns Over at No fuel Replenish fuel –
Normal Speed but Compression leak Check the S-14
Does Not Start compression
pressure and repair
Improper valve clearance Adjust S-16
Defective ignition coil Replace S-25
Defective spark plug Adjust spark plug gap G-10
or replace
Defective ignitor Replace S-26
Defective fuel system Check fuel line and –
carburetor and repair
Over choked Clean spark plug –
Flooding from carburetor Check carburetor and –
repair / replace
Clogged air cleaner Clean or replace G-16
Rough Low-Speed Defective ignition coil Replace S-25
Running and Idling Defective spark plug Adjust spark plug gap G-10
or replace
Defective ignitor Replace G-26
Incorrect carburetor idle adjustment Adjust S-20
Incorrect governor adjustment Adjust S-20
Improper valve clearance Adjust S-16
Rough High-Speed Defective ignitor Replace S-26
Running Defective spark plug Adjust spark plug gap G-10
or replace
Defective ignition coil Replace S-25
Incorrect governor adjustment Adjust S-20
W1014322

KiSC issued 01, 2006 A

S-1
WG972-E2, DF972-E2, WSM GASOLINE / LPG ENGINE

Reference
Symptom Probable Cause Solution
Page
Engine Speed Does Incorrect governor adjustment Adjust S-20
Not Increase Defective ignitor Replace S-26
Incorrect carburetor adjustment Adjust S-20
Clogged air cleaner Clean or replace G-16
Defection Output Improper intake or exhaust valve sealing Replace S-52
Incorrect governor adjustment Adjust S-20
Excessive carbon in engine Remove carbon –
Improper valve clearance Adjust S-16
Piston ring and cylinder worn Replace S-64
Clogged air cleaner Clean or replace G-16
Engine Noise Improper valve clearance Adjust S-16
Spark knock due to low-octane fuel or carbon Use higher-octane –
fuel and remove
carbon
Rattles from loosely mounted external Retighten –
components
W1060742

[2] FOR LPG FUEL

Reference
Symptom Probable Cause Solution
Page
Engine Turns Over at No LPG fuel Replenish LPG fuel –
Normal Speed but Check of taking valve
Does Not Start of LPG tank
Check of shut off
valve
Vacuum lock system is defective Check of vacuum S-23
hose
Replace of vaporizer
Mistake of throttle lever position Set the throttle lever S-20
to the low idle
position
Rough Low-Speed Lack of amount of gas supply Replenish LPG fuel –
Running and Idling Check of shut off
valve
Idling is defective Replace of vaporizer G-20
Draining the tar from
vaporizer
Defection Output Density of the LPG is rich Replace of vaporizer –
LPG shortage Repair or replace of –
fuel system
Replace of vaporizer
W1014322

KiSC issued 01, 2006 A

S-2
WG972-E2, DF972-E2, WSM GASOLINE / LPG ENGINE

[3] FOR ELECTRONIC GOVERNOR

■ NOTE
• This troubleshooting describe the procedure which does not use the service tool (soft wear).
Engine does not start : Step 1

(1) Refer to [Adjust Governor Lever of Electronic Governor]

KiSC issued 01, 2006 A

S-3
WG972-E2, DF972-E2, WSM GASOLINE / LPG ENGINE

Engine does not start : Step 2

(1) Refer to the [Air Gap of Engine Speed Sensor for Electronic Governor]
(2) Refer to the [Resistance of Engine Speed Sensor for Electronic Governor]

KiSC issued 01, 2006 A

S-4
WG972-E2, DF972-E2, WSM GASOLINE / LPG ENGINE

Engine unstable

(1) Refer to the [Adjust Governor Lever of Electronic Governor]

KiSC issued 01, 2006 A

S-5
WG972-E2, DF972-E2, WSM GASOLINE / LPG ENGINE

2. SERVICING SPECIFICATIONS
ENGINE BODY
Item Factory Specification Allowable Limit
Valve Clearance (Cold) 0.145 to 0.185 mm –
0.00571 to 0.00728 in.
Compression Pressure – 1.27 MPa 0.88 MPa
13.0 kgf/cm2 9.0 kgf/cm2
185 psi 128 psi

Variance Among – 10 % or less

Cylinder
Top Clearance 1.35 to 1.65 mm –
0.0531 to 0.0650 in.
Cylinder Head Surface Flatness – 0.05 mm
0.0020 in.
Valve Recessing (Intake and Exhaust) -0.10 to 0.10 mm 0.30 mm
-0.0039 to 0.0039 in. 0.0118 in.
Valve Stem to Valve Guide Clearance 0.030 to 0.057 mm 0.10 mm
0.00118 to 0.00224 in. 0.0039 in.

Valve Stem O.D. 5.968 to 5.980 mm –

0.23496 to 0.23543 in.

Valve Guide I.D. 6.010 to 6.025 mm –

0.23661 to 0.23720 in.
Valve Face Angle 0.785 rad –
45 °
Valve Seat Angle 0.785 rad –
45 °
Width 2.12 mm –
0.0835 in.
Valve Timing (Intake Valve) Open 0.35 rad –
20 °
before T.D.C.

Close 0.79 rad –

45 °
after B.D.C.
Valve Timing (Exhaust Valve Valve) Open 0.87 rad –
50 °
before B.D.C.

Close 0.26 rad –

15 °
after T.D.C.

KiSC issued 01, 2006 A

S-6
WG972-E2, DF972-E2, WSM GASOLINE / LPG ENGINE

ENGINE BODY (Continued)

Item Factory Specification Allowable Limit
Valve Spring Free Length 31.3 to 31.8 mm 28.4 mm
1.232 to 1.252 in. 1.118 in.

Tilt – 1.2 mm
0.047 in.

Setting Load / 64.7 N / 27.0 mm 54.9 N / 27.0 mm

Setting Length 6.6 kgf / 27.0 mm 5.6 kgf / 27.0 mm
14.6 lbs / 1.063 in. 12.3 lbs / 1.063 in.
Rocker Arm Shaft to Rocker Arm Oil Clearance 0.016 to 0.045 mm 0.15 mm
0.00063 to 0.00177 in. 0.0059 in.

Rocker Arm Shaft O.D. 10.473 to 10.484 mm –

0.41232 to 0.41276 in.

Rocker Arm I.D. 10.500 to 10.518 mm –

0.41339 to 0.41410 in.
Push Rod Alignment – 0.25 mm
0.0098 in.
Tappet to Tappet Guide Bore Oil Clearance 0.016 to 0.052 mm 0.10 mm
0.00063 to 0.00205 in. 0.0039 in.

Tappet O.D. 17.966 to 17.984 mm –

0.70732 to 0.70803 in.

Tappet Guide Bore I.D. 18.000 to 18.018 mm –

0.70866 to 0.70937 in.
Timing Gear 0.043 to 0.124 mm 0.15 mm
Crank Gear to Idle Gear Backlash 0.00169 to 0.00488 in. 0.0059 in.

0.047 to 0.123 mm 0.15 mm

Idle Gear to Cam Gear Backlash 0.00185 to 0.00484 in. 0.0059 in.

0.046 to 0.124 mm 0.15 mm

Idle Gear to Injection Pump Gear Backlash 0.00181 to 0.00488 in. 0.0059 in.

0.041 to 0.123 mm 0.15 mm

Crank Gear to Oil Pump Drive Gear Backlash 0.00161 to 0.00484 in. 0.0059 in.
Idle Gear Side Clearance 0.20 to 0.51 mm 0.80 mm
0.0079 to 0.0201 in. 0.0315 in.
Camshaft Side Clearance 0.15 to 0.31 mm 0.5 mm
0.0059 to 0.0122 in. 0.0197 in.

Alignment – 0.01 mm
0.0004 in.

Cam Height (Intake 26.88 mm 26.83 mm

and Exhaust) 1.0583 in. 1.0563 in.

KiSC issued 01, 2006 A

S-7
WG972-E2, DF972-E2, WSM GASOLINE / LPG ENGINE

ENGINE BODY (Continued)

Item Factory Specification Allowable Limit
Camshaft Journal to Cylinder Block Bore Oil Clearance 0.050 to 0.091 mm 0.15 mm
0.00197 to 0.00358 in. 0.0059 in.

Camshaft Journal O.D. 32.934 to 32.950 mm –

1.29661 to 1.29724 in.

Cylinder Block Bore I.D. 33.000 to 33.025 mm –

1.29921 to 1.30020 in.
Idle Gear Shaft to Idle Gear Bushing Oil Clearance 0.020 to 0.084 mm 0.10 mm
0.00079 to 0.00331 in. 0.0039 in.

Idle Gear Shaft O.D. 19.967 to 19.980 mm –

0.78610 to 0.78661 in.

Idle Gear Bushing I.D. 20.000 to 20.051 mm –

0.78740 to 0.78941 in.
Piston Pin Bore I.D. 20.000 to 20.013 mm 20.05 mm
0.78740 to 0.78791 in. 0.7894 in.
Piston Pin to Small End Bushing Oil Clearance 0.014 to 0.038 mm 0.10 mm
0.00055 to 0.00150 in. 0.0039 in.

Piston Pin O.D. 20.002 to 20.011 mm –

0.78748 to 0.78783 in.

Small End Bushing I.D. 20.025 to 20.040 mm –

0.78839 to 0.78897 in.
Piston Pin to Small End Bushing Oil Clearance 0.015 to 0.075 mm 0.15 mm
(Spare Parts) 0.00059 to 0.00295 in. 0.0059 in.

Small End Bushing I.D. 20.026 to 20.077 mm –

0.78845 to 0.79043 in.
Piston Ring Gap Top Ring 0.15 to 0.35 mm 1.25 mm
0.0059 to 0.0138 in. 0.0492 in.

Second Ring 0.30 to 0.45 mm 1.25 mm

0.0118 to 0.0177 in. 0.0492 in.

Oil Ring 0.20 to 0.70 mm 1.25 mm

(Upper and lower 0.0079 to 0.0276 in. 0.0492 in.
rail)
Piston Ring to Piston Ring Groove Top Ring 0.080 to 0.120 mm 0.15 mm
Second Ring 0.00315 to 0.00472 in. 0.0059 in.
(Clearance)

Oil Ring 0.065 to 0.10 mm 0.15 mm

(Clearance) 0.0026 to 0.0039 in. 0.0059 in.
Connecting Rod Alignment – 0.05 mm
0.0020 in.
Crankshaft Side Clearance 0.15 to 0.31 mm 0.50 mm
0.0059 to 0.0122 in. 0.0197 in.

Alignment – 0.02 mm
0.0008 in.

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WG972-E2, DF972-E2, WSM GASOLINE / LPG ENGINE

ENGINE BODY (Continued)

Item Factory Specification Allowable Limit
Crankpin to Crankpin Bearing Oil Clearance 0.020 to 0.051 mm 0.15 mm
0.00079 to 0.00201 in. 0.0059 in.

Crankpin O.D. 33.959 to 33.975 mm –

1.33697 to 1.33760 in.

Crankpin Bearing I.D. 33.995 to 34.010 mm –

1.33893 to 1.33898 in.
Crankshaft Journal to Crankshaft Bearing 1 Oil Clearance 0.034 to 0.106 mm 0.20 mm
0.00134 to 0.00417 in. 0.0079 in.

Crankshaft Journal O.D. 43.934 to 43.950 mm –

1.72968 to 1.73031 in.

Crankshaft Bearing 1 O.D. 43.984 to 44.040 mm –

1.73165 to 1.73386 in.
Crankshaft Journal to Crankshaft Bearing 2 Oil Clearance 0.028 to 0.059 mm 0.20 mm
(Flywheel Side) 0.00110 to 0.00232 in. 0.0079 in.

Crankshaft Journal O.D. 43.934 to 43.950 mm –

1.72968 to 1.73031 in.

Crankshaft Bearing 2 I.D. 43.978 to 43.993 mm –

1.73142 to 1.73201 in.
Crankshaft Journal to Crankshaft Bearing 3 Oil Clearance 0.028 to 0.059 mm 0.20 mm
(Intermediate) 0.00110 to 0.00232 in. 0.0079 in.

Crankshaft Journal O.D. 43.934 to 43.950 mm –

1.72968 to 1.73031 in.

Crankshaft Bearing 3 I.D. 43.978 to 43.993 mm –

1.73142 to 1.73201 in.
Cylinder Liner I.D. 74.500 to 74.519 mm 74.669 mm
[Standard] 2.93307 to 2.93382 in. 2.93972 in.
Cylinder Liner I.D. 75.000 to 75.019 mm 75.150 mm
[Oversize : 0.5 mm (0.01969 in.)] 2.95276 to 2.95350 in. 2.95866 in.
W10724730

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WG972-E2, DF972-E2, WSM GASOLINE / LPG ENGINE

LUBRICATING SYSTEM
Item Factory Specification Allowable Limit
Engine Oil Pressure At Idle Speed More than 49 kPa –
0.5 kgf/cm2
7 psi

At Rated Speed 196 to 441 kPa 147 kPa

2.0 to 4.5 kgf/cm2 1.5 kgf/cm2
28 to 64 psi 21 psi
Inner Rotor to Outer Rotor Clearance 0.03 to 0.14 mm –
0.0012 to 0.0055 in.
Outer Rotor to Pump Body Clearance 0.07 to 0.15 mm –
0.0028 to 0.0059 in.
Inner Rotor to Cover Clearance 0.075 to 0.135 mm –
0.00295 to 0.00531 in.
W1013874

COOLING SYSTEM
Item Factory Specification Allowable Limit
Fan Belt Tension 7.0 to 9.0 mm / 98 N –
0.28 to 0.35 in. / 98 N
(10 kgf, 22 lbs)
Thermostat Valve Opening 69.5 to 72.5 °C –
Temperature 157.1 to 162.5 °F
(At Beginning)

Valve Opening 85 °C –
Temperature 185 °F
(Opened
Completely)
Radiator Cap Pressure Falling 10 seconds or more –
Time 88 → 58 kPa
0.9 → 0.6 kgf/cm2
13 → 9 psi
Radiator Weak Leakage No leak at specified –
Test Pressure pressure
157 kPa
1.6 kgf/cm2
23 psi
W1013874

IGNITION SYSTEM
Item Factory Specification Allowable Limit
Spark Plug (NGK : BKR4E) Plug Gap 0.6 to 0.7 mm –
0.024 to 0.028 in.
Resistance of Ignition Coil Primary (+) - (-) 1.87 to 2.53 Ω at 20 °C –

Secondary Side 15.4 to 20.6 kΩ at 20 °C –

(Primary (+) - Plug
Cap)
Pick-up Sensor Resistance 1.85 to 2.45 kΩ at 20 °C –
W1013874

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ELECTRICAL SYSTEM
Item Factory Specification Allowable Limit
Starter Commutator 32.0 mm 31.0 mm
(O.D.) 1.260 in. 1.220 in.

Difference Less than 0.5 mm 0.4 mm

(O.D.) 0.002 in. 0.016 in.

Mica 0.5 to 0.8 mm 0.2 mm

(Undercut) 0.020 to 0.031 in. 0.008 in.

Brush 17.0 mm 11.5 mm

(Length) 0.669 in. 0.453 in.
Alternator No-load Output AC 20 V or more at –
(Voltage) 5200 min-1 (rpm)
Regulator Regulating Voltage 14 to 15 V –
Fuel Cut Off Solenoid For Gasoline 38 Ω at 20 °C –
(Resistance)

For LPG 28 Ω at 20 °C –
(Resistance)
W10138740

ELECTRONIC GOVERNOR
Item Factory Specification Allowable Limit
Engine Speed Sencer to Ring Gear Air Gap 0.8 to 1.2 mm –
(for Kubota original parts) 0.031 to 0.047 in.

Resistance Approx. 1.6 kΩ –

W10139730

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WG972-E2, DF972-E2, WSM GASOLINE / LPG ENGINE

3. TIGHTENING TORQUES
Screws, bolts and nuts must be tightened to the specified torque using a torque wrench, several screws, bolts and
nuts such as those used on the cylinder head must be tightened in proper sequence and the proper torque.

[1] TIGHTENING TORQUES FOR SPECIAL USE SCREWS, BOLTS AND

NUTS
■ NOTE
• For “*” marked screws, bolts and nuts on the table, apply engine oil to their threads and seats before
tightening.
• The letter “M” in Size x Pitch means that the screw, bolt or nut dimension stands for metric. The size is
the nominal outside diameter in mm of the threads. The pitch is the nominal distance in mm between two
threads.
Item Size x Pitch N·m kgf·m ft-lbs
*Cylinder head cover screw M6 x 1 6.9 to 11.3 0.7 to 1.15 5.1 to 8.3
*Rocker arm bracket screw M6 x 1 9.8 to 11.3 1.00 to 1.15 72.3 to 83.2
*Cylinder head screw M8 x 1.25 37.3 to 42.2 3.8 to 4.3 27.5 to 31.1
*Fan drive pulley screw M12 x 1.5 98.1 to 107.9 10.0 to 11.0 72.3 to 79.6
*Idle gear mounting screw M6 x 1 9.8 to 11.3 1.00 to 1.15 7.2 to 8.3
*Connecting rod screw M7 x 0.75 26.5 to 30.4 2.7 to 3.1 19.5 to 22.4
*Flywheel screw M10 x 1.25 53.9 to 58.8 5.5 to 6.0 39.8 to 43.4
Bearing case cover mounting screw M6 x 1 9.8 to 11.3 1.00 to 1.15 7.23 to 8.32
*Main bearing case screw 2 M7 x 1 26.5 to 30.4 2.7 to 3.1 19.5 to 22.4
*Main bearing case screw 1 M6 x 1 12.7 to 15.7 1.3 to 1.6 9.4 to 11.6
Oil pressure switch PT 1/8 14.7 to 19.6 1.5 to 2.0 10.8 to 14.5
Starter (C terminal nut) – 5.9 to 11.8 0.6 to 1.2 4.3 to 8.7
Spark plug M14 x 1.25 19.6 to 24.5 2.0 to 2.5 14.5 to 18.1
Drain plug M12 x 1.25 32.4 to 37.3 3.3 to 3.8 23.9 to 27.5
Carburetor mounting nut M8 x 1.0 23.5 to 27.5 2.4 to 2.8 17.4 to 20.2
Joint for LPG hose of vaporizer
PT - 1/4 19.6 to 32.9 2.0 to 4.0 14.5 to 28.9
(local arrangement)
Joint for vapor hose of vaporizer PT - 3/8 29.4 to 58.8 3.0 to 6.0 21.7 to 43.4
Joint for water hose of vaporizer PT - 3/8 29.4 to 58.8 3.0 to 6.0 21.7 to 43.4
Actuator mounting screw M5 x 0.8 4.9 to 0.8 0.45 to 0.55 3.6 to 4.0
Actuator flange screw M6 x 1.0 9.8 to 11.3 1.00 to 1.15 7.23 to 8.32
Governor lever nut M6 x 1.0 9.8 to 11.3 1.00 to 1.15 7.23 to 8.32
W1013236

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WG972-E2, DF972-E2, WSM GASOLINE / LPG ENGINE

[2] TIGHTENING TORQUES FOR GENERAL USE SCREWS, BOLTS AND

NUTS
When the tightening torques are not specified, tighten the screws, bolts and nuts according to the table below.
Grade Standard Screw and Bolt Special Screw and Bolt

Nominal Unit
Diameter N·m kgf·m ft-lbs N·m kgf·m ft-lbs

M6 7.9 to 9.3 0.80 to 0.95 5.8 to 6.9 9.8 to 11.3 1.00 to 1.15 7.23 to 8.32
M8 17.7 to 20.6 1.8 to 2.1 13.0 to 15.2 23.5 to 27.5 2.4 to 2.8 17.4 to 20.3
M10 39.2 to 45.1 4.0 to 4.6 28.9 to 33.3 48.1 to 55.9 4.9 to 5.7 35.4 to 41.2
M12 62.8 to 72.6 6.4 to 7.4 46.3 to 53.5 77.5 to 90.2 7.9 to 9.2 57.1 to 66.5
W10371750

Screw and bolt material grades are shown by numbers punched on the screw and bolt heads. Prior to
tightening, be sure to check out the numbers as shown below.
Punched number Screw and bolt material grade
None or 4 Standard screw and bolt SS41, S20C
7 Special screw and bolt S43C, S48C (Refined)
W1012705

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WG972-E2, DF972-E2, WSM GASOLINE / LPG ENGINE

4. CHECKING, DISASSEMBLING AND SERVICING

[1] CHECKING AND ADJUSTING
(1) Engine Body
Compression Pressure
1. Run the engine until it is warmed up.
2. Stop the engine.
3. Remove the air cleaner, the muffler and all spark plugs.
4. Set a compression tester with the adaptor to the spark plug hole.
5. Run the engine with the starter for 5 to 10 seconds keeping
throttle valve fully open and read the maximum compression
pressure.
6. Repeat steps 4 and 5 for each cylinder.
7. If the measurement is below the allowable limit, apply a small
amount of oil to the cylinder wall through the spark plug hole and
measure the compression pressure again.
8. If the compression pressure is still less than the allowable limit,
check the top clearance, valve clearance and cylinder head.
9. If the compression pressure increases after applying oil, check
the cylinder wall and piston rings.
■ NOTE
• Check the compression pressure with the specified valve
clearance.
• Always use a fully charged battery for performing this test.
• Variances in cylinder compression values should be under
10 %.
1.27 MPa
Factory spec. 13.0kgf/cm2
185 psi
Compression pressure
0.88 MPa
Allowable limit 9.0kgf/cm2
128 psi
W1048776

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WG972-E2, DF972-E2, WSM GASOLINE / LPG ENGINE

Top Clearance
1. Remove the cylinder head. (Do not attempt to remove the
cylinder head gasket.)
2. Move the piston up and stick a strip of fuse [1.5 mm dia. (0.059
in. dia.), 5 to 7 mm long (0.197 to 0.276 in. long)] on the piston
head at three positions with grease so as to avoid the intake and
exhaust valves and the combustion chamber ports.
3. Lower the piston, and install the cylinder head and tighten the
cylinder head screws to the specified torque.
4. Turn the flywheel until the piston exceeds top dead center.
5. Remove the cylinder head, and measure the thickness of the
squeezed fuses.
6. If the measurement is not within the factory specifications, check
the oil clearance between the crankpin and crankpin bearing and
between the piston pin and small end bushing.
■ NOTE
• After checking the top clearance, be sure to assemble the
cylinder head with a new cylinder head gasket.
1.35 to 1.65 mm
Top clearance Factory spec.
0.0531 to 0.0650 in.

37.3 to 42.2 N·m

Tightening torque Cylinder head screws 3.8 to 4.3 kgf·m
27.5 to 31.1 ft-lbs

(1) Fuse
W1020190

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Adjusting the Valve Clearance

■ IMPORTANT
• The valve clearance must be checked and adjusted when
engine is cold.
1. Remove the cylinder head cover (1) and the spark plugs.
2. Align the “1TC” mark (2) on the flywheel and alignment mark (3)
on the rear end plate so that the No. 1 piston comes to the
compression top dead center.
3. Check the following valve clearance marked with “★” using a
thickness gauge.
4. If the clearance is not within the factory specifications, adjust with
the adjusting screw.
5. Then turn the flywheel 6.28 rad (360 °), and align the “1TC” mark
(2) on the flywheel and alignment mark (3) on the rear end plate
so that the No. 1 piston comes to the overlap position.
6. Check the following valve clearance marked with “✩” using a
feeler gauge.
7. If the clearance is not within the factory specifications, adjust with
the adjusting screw.
Engine Valve
arrangement
Intake valve Exhaust valve
Adjustable cylinder
location of piston
No. 1 ★ ★
No. 2 ✩ ★
No. 3 ★ ✩
★ : When No. 1 piston is at the compression top dead center position.
✩ : When No. 1 piston is at the overlap position.

Intake and exhaust 0.145 to 0.185 mm

Factory spec.
valve clearance (cold) 0.00571 to 0.00728 in.

■ NOTE
• The sequence of cylinder numbers is given as No. 1, No. 2
and No. 3 starting from the gear case side.
• After adjusting the valve clearance, secure the adjusting
screw with the lock nut.
(1) Cylinder Head Cover A : Gear Case Side
(2) “1TC” Mark
(3) Alignment Mark
W10898490

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(2) Lubricating System

Engine Oil Pressure
1. Remove the engine oil pressure switch, and set an oil pressure
tester.
2. Start the engine. After warming up, measure the oil pressure of
both idling and rated speeds.
3. If the oil pressure is less than the allowable limit, check the
following.
• Engine oil insufficient
• Oil pump defective
• Oil strainer clogged
• Oil filter cartridge clogged
• Oil gallery clogged
• Excessive oil clearance
• Foreign matter in the relief valve
(When reassembling)
• After checking the engine oil pressure, tighten the engine oil
pressure switch to the specified torque.
More than 49 kPa
At idle Factory
0.5 kgf/cm2
speed spec.
7 psi
196 to 441 kPa
Factory
Engine oil pressure 2.0 to 4.5 kgf/cm2
spec.
At rated 28 to64 psi
speed 147 kPa
Allowable
1.5 kgf/cm2
limit
21 psi

14.7 to 19.6 N·m

Tightening torque Oil pressure switch 1.5 to 2.0 kgf·m
10.8 to 14.5 ft-lbs

W10349520

(3) Cooling System

Fan Belt Tension
1. Measure the deflection (A), depressing the belt halfway between
the fan drive pulley and alternator pulley at specified force 98 N
(10 kgf, 22 lbs).
2. If the measurement is not within the factory specifications, loosen
the alternator mounting screws and relocate the alternator to
adjust.
7.0 to 9.0 mm
Deflection (A) Factory spec.
0.28 to 0.35 in.

(A) Deflection
W1021011

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WG972-E2, DF972-E2, WSM GASOLINE / LPG ENGINE

Fan Belt Damage and Wear

1. Check the fan belt for damage.
2. If the fan belt is damaged, replace it.
3. Check if the fan belt is worn and sunk in the pulley groove.
4. If the fan belt is nearly worn out and deeply sunk in the pulley
groove, replace it.
(A) Good (B) Bad
W1021108

Thermostat Valve Opening Temperature

1. Suspend the thermostat in the water by a string with its end
inserted between the valve and seat.
2. Heating the water gradually, read the temperature when the
valve opens and leaves the string.
3. Continue heating and read the temperature when the valve
opens approx. 8 mm (0.315 in.).
4. If the measurement is not within the factory specifications,
replace the thermostat.
Thermostat’s valve 69.5 to 72.5 °C
Factory spec.
opening temperature 157.1 to 162.5 °F
Temperature at which
85 °C
thermostat completely Factory spec.
185 °F
opens
W1035849

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WG972-E2, DF972-E2, WSM GASOLINE / LPG ENGINE

CAUTION
• When removing the radiator cap, wait at least ten minutes after the engine has stopped and cooled down.
Otherwise, hot water may gush out, scalding nearby people.
Radiator Cap Air Leakage
1. Set a radiator tester (1) and an adaptor (2) on the radiator cap.
2. Apply the specified pressure (88 kPa, 0.9 kgf/cm2, 13 psi), and
measure the time for the pressure to fall to 59 kPa (0.6 kgf/cm2,
9 psi).
3. If the measurement is less than the factory specification, replace
the radiator cap.
More than 10 seconds
for pressure fall from
Pressure falling time Factory spec. 88 to 59 kPa
(from 0.9 to 0.6 kgf/cm2,
from 13 to 9 psi)

(1) Radiator Tester (2) Adaptor

W1054156
Radiator Water Leakage
1. Pour a specified amount of water into the radiator.
2. Set a radiator tester (1) and an adapter (2) and raise the water
pressure to the specified pressure.
3. Check the radiator for water leaks.
4. For water leak from the pinhole, repair with the radiator cement.
When water leak is excessive, replace the radiator.
157 kPa
Radiator water leakage
Factory spec. 1.6 kgf/cm2
test pressure
23 psi

(1) Radiator Tester (2) Adaptor

W1016903

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WG972-E2, DF972-E2, WSM GASOLINE / LPG ENGINE

(4) Fuel System

Adjusting Governor
1. Loosen the governor lever nut (3).
2. Set the throttle valve to the fully "OPEN" position with the
governor lever (1), turn the groove on the governor lever shaft (2)
fully clockwise with a screwdriver (to open the governor
completely), and then tighten the nut (3) in this position.
23.5 to 27.5 N·m
Tightening torque Governor lever nut 2.4 to 2.8 kgf·m
17.4 to 20.2 ft-lbs

■ NOTE
• Insert the governor lever to the position 2 mm (A) away from the
fork lever shaft end.
(1) Governor Lever A : 2 mm (0.079 in.)
(2) Governor Lever Shaft B : Open Direction
(3) Governor Lever Nut
W1036105

Adjusting Engine Speed

1. Warm up the engine at a medium speed for 10 to 15 minutes.
2. Engine speed is adjusted to approx. 1500 min-1 (rpm) by the
speed control lever (3).
3. Throttle valve (1) is closed by hand and engine speed is adjusted
with the throttle adjust screw (2) to 1200 min-1 (rpm) (1100 to
1300 min-1 (rpm)).
4. Adjust the low-idling speed adjust screw (4) until the engine
speed reaches 1500 min-1 (rpm) (1400 to 1600 min-1 (rpm)) with
the speed control lever (3) in the minimum speed position.
5. Adjust the high-idling speed adjust screw (5) until the engine
speed reaches 3850 min-1 (rpm) (3850 to 3950 min-1 (rpm)) with
the speed control lever (3) in the maximum speed position.
1500 min-1 (rpm)
Lo-idling speed (1400 to 1600 min-1
(rpm))
Factory spec.
3850 min-1 (rpm)
Hi-idling speed (3850 to 3950 min-1
(rpm))

(1) Throttle Valve (4) Low-idling Adjust Screw

(2) Throttle Adjust Screw (5) High-idling Adjust Screw
(3) Speed Control Lever
W1017430
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WG972-E2, DF972-E2, WSM GASOLINE / LPG ENGINE

Carburetor (WG972-E2)
Dual Fuel Carburetor (DF972-E2)
The carburetor is tamper resistant; the idle mixture screw has
been covered by tamper plug after adjustment at the factory.
(1) Tamper Resistance
W1017786

Replacement of Altitude Compensation Kit (Main Jet and Pilot

Jet)
1. Remove the carburetor.
2. Loosen the drain screw (3) to let fuel out.
3. Remove the gasoline solenoid (6).
4. Remove the main jet (5).
5. Install the high-altitude kit's main jet onto the carburetor.
6. Tighten the throttle adjust screw (4) and remove the screw (1).
7. Replace the existing pilot jet (2) with the high-altitude kit's pilot jet.
8. Install the gasoline solenoid (6).
9. Install the carburetor in place.
10.Readjust the governor.
11.Adjust the engine speed.
■ NOTE
• After install the carburetor, the adjustment of governor and
engine speed are executed.
• Prepare a screwdriver that fits the main jet / pilot jet screws
in order not to damage the main jet and pilot jet.
• Replace the air cleaner packing and the carburetor packing
with new ones.
• Make sure there is no leak at the air cleaner packing and the
carburetor packing.
■ IMPORTANT
• Keep the carburetor inner parts which is removed from
standard carburetor.
23.5 to 27.5 N·m
Carburetor mounting nut 2.4 to 2.8 kgf·m
17.4 to 20.2 ft-lbs
7.8 to 11.7 N·m
Gasoline solenoid 0.8 to 1.2 kgf·m
5.8 to 8.7 ft-lbs
Tightening torque
1.0 to 2.9 N·m
Main jet 0.1 to 0.29 kgf·m
5.0 to 15.2 ft-lbs
1.0 to 3.9 N·m
Pilot jet 0.1 to 0.40 kgf·m
5.0 to 20.5 ft-lbs

(1) Pilot Screw (4) Throttle Adjust Screw

(2) Pilot Jet (5) Main Jet
(3) Drain Screw (6) Gasoline Solenoid
W1018491

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LPG Vaporizer Regulator (DF972-E2)

LPG vaporizer regulator is tamper resistant; the main and idle
pressure adjustment screws have been covered by tamper caps
after adjustment at the factory.
(1) Tamper Resistance
W10371670

Vaporizer Joints (DF972-E2)

1. The direction of the joint for vapor hose is decided upon and a
mark (2) is made.
2. The direction of the joint for water hose is decided upon and a
mark is made.
■ NOTE
• Vaporizer must be installed in an upright position (water
hoses at bottom).
• The joints (fitting) can be adjusted to any position. The joint
must be tight in that position.
• Apply an approved for GAS or LPG use liquid gasket (Three
Bond 1104 or its equivalent) to thread (see figure) and
tighten it.
• Drain plug (1) must not be obstructed ; so that it can be
removed during maintenance.
• Apply liquid gasket to the thread of each joint and tighten
them.
• After selecting the joint (fitting) positions, insure that there
are no leaks.
19.6 to 32.9 N·m
Joint for LPG hose
2.0 to 4.0 kgf·m
(local arrangement)
14.5 to 28.8 ft-lbs
Tightening torque
Joint for vapor hose 29.4 to 58.8 N·m
3.0 to 6.0 kgf·m
Joint for water hose 21.6 to 43.2 ft-lbs

(1) Drain Plug (3) Liquid Gasket

(2) Mark (4) Thread of Joint
W1099553

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WG972-E2, DF972-E2, WSM GASOLINE / LPG ENGINE

Vaporizer Piping (DF972-E2)

1. Connect the water hose (1) and (2) through the vaporizer.
2. The water joint part of vaporizer is adjusted to the upper side (A)
and coolant is replenished through radiator, to bleed air in the
vaporizer.
3. Vaporizer (3) is returned to former position.
4. Connect the vapor hose.
5. Connect the vacuum lock hose (4).
6. Tighten the vaporizer (3).
7. Connect the LPG hose.
• O.D. of joint for vapor hose: 12.7 mm (0.5 in.)
• O.D. of joint for water hose: 9.0 mm (0.35 in.)

CAUTION
• All fuel connections added to this engine must be installed
by qualified personnel and utilizing recognized procedures
and standards.
• These non-KUBOTA installed parts, such as hoses, fittings,
piping, should be approved for LPG use and conform to UL,
CSA, NFPA, and all other recognized standards.
• An approved, listed fuel filter and electromechanical
positive shutoff must be installed between the LPG tank and
KUBOTA vaporizer. (Not KUBOTA Provided)
■ NOTE
• The LPG liquid in joint (fitting) to the vaporizer / regulator is
not provided in the KIT by KUBOTA, due to the many
different connection requirements by the OEM.
The female thread into the vaporizer / regulator is a PT 1/4
METRIC thread. To insure good sealing the correct fitting
must by used.
• Vapor hose between the vaporizer and mixer must be of 280
to 320 mm (11.02 to 12.60 in.) in length, to assure correct
emissions and proper operation.
• Perform air bleeding of the vaporizer (water passage).
• Each hose must be tightened with a hose clamp.
(1) Water Hose A : Water Joint
(2) Water Hose
(3) Vaporizer
(4) Vacuum Lock Hose
W1037280

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(5) Ignition System

Timing Light Test
1. Set the timing light to High-tension cord.
2. Close the fuel cocks.
3. Cranking the engine.
4. If the timing light blinks, the spark plug and ignition coil are
normal.
5. If the timing light does not blink, check the spark plug / ignition
coil.
W10125620
Ignition Timing
1. Using a timing light, check that the ignition timing (stamps on the
flywheel) (4) is aligned with the mark (3) on the rear end plate (2).
2. The pick-up sensor is tamper resistant (5); the ignition timing
adjustment screw has been covered after adjustment at the
factory.
0.331 to 0.401 rad
Ignition timing Factory spec. (19 to 23 °) before T.D.C
at 3600 min-1 (rpm)

(1) Flywheel (4) Ignition Timing

(2) Rear End Plate (5) Tamper Resistance
(3) Mark
W1103663

Resistance of Pick-Up Sensor

1. Disconnect the connector.
2. Measure the resistance with an ohmmeter.
3. If the resistance is not with in the factory specifications, replace it.
Factory
Resistance A-B 1.85 to 2.45 kΩ at 20 °C
spec.

■ NOTE
• This check sheet shows the results of the test conducted by
using the "Sanwa-made testers SP-10 / SP-150" (analog
meter).
• Use of other testers than those above may show different
measured results.
W1051348

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Spark Test
1. Remove the spark plug, put it inside the high voltage cord cap
firmly, and then ground the threaded section to the engine body
(not to painted or resin parts).
2. Rotate the starter with the key switch and check that the plug
sparks.

CAUTION
• This test is hazardous of electric shocks. Never use hand or
screwdriver to press the plug to ground it to the engine
body.
• Keep inflammable away from the engine.
W1106847
Resistance of Igniton Coil
1. Disconnect the connector.
2. Measure the resistance with an ohmmeter.
3. If the resistance is not with in the factory specifications, replace it.
Factory A-B 1.87 to 2.53 kΩ at 20 °C
Resistance
spec. A-C 15.4 to 20.6 kΩ at 20 °C

■ NOTE
• This check sheet shows the results of the test conducted by
using the "FLUKE MULTMETER 110 SERIES" (degital
meter).
• Use of other testers than those above may show different
measured results.
A : Terminal (+) C : Hight Tension Cord
B : Terminal (-)
W1107395
Air Gap of Engine Speed Sensor for Electronic Governor
1. Measure the air gap with a feeler gauge.
2. If air gap differs from the factory specification, readust the air gap.
0.8 to 1.2 mm
Air gap Factory spec.
0.031 to 0.047 in.

■ NOTE
• The described numerical value is the values of KBT parts.
• Checking sensor as described in the manual of sensor
maker.
• The described valve is the data of supply of kubota.
Follow the instruction of OEM for parts adopted by OEM.
W1019297
Resistance of Engine Speed Sensor for Electronic Governor
1. Measure the resistance with an ohmmeter.
2. If the resistance is not with in the factory specifications, replace it.
Resistance Factory spec. Approx. 1.6 fΩ

■ NOTE
• The described numerical value is the values of KBT parts.
• Checking sensor as described in the manual of sensor
maker.
• This check sheet shows the results of the test conducted by
using the “FLUKE MULTMETER 110 SERIES”.
• The described valve is the data of supply of kubota.
Follow the instruction of OEM for parts adopted by OEM.
W1109303

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Resistance of Ignitor
1. Disconnect the connector.
2. Measure the resistance with an ohmmeter.
3. If the resistance is not with in the factory specifications, replace it.
W1109304

Ignitor Check Chart

Negative
A B C D E F G H
Positive
A 10 to 40 kΩ 10 to 40 kΩ 11 to 47 kΩ infinity infinity infinity infinity
B 10 to 40 kΩ 0.33 to 1.3 kΩ 1.8 to 7.3 kΩ infinity infinity infinity infinity
C 10 to 40 kΩ 0.33 to 1.3 kΩ 1.5 to 6.0 kΩ infinity infinity infinity infinity
D 11 to 47 kΩ 1.8 to 7.3 kΩ 1.5 to 6.0 kΩ infinity infinity infinity infinity
E infinity infinity infinity infinity infinity infinity infinity

F 2 megohm 2 megohm 2 megohm 2 megohm infinity infinity infinity

(minimum) (minimum) (minimum) (minimum)
2 megohm 2 megohm 2 megohm 2 megohm
G infinity infinity infinity
(minimum) (minimum) (minimum) (minimum)
2 megohm 2 megohm 2 megohm 2 megohm
H infinity infinity infinity
(minimum) (minimum) (minimum) (minimum)

■ NOTE
• This check sheet shows the results of the test conducted by using the "FLUKE MULTMETER 110 SERIES"
(degital meter).
• Use of other testers than those above may show different measured results.

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(6) Electrical System

Motor Test

CAUTION
• Secure the starter to prevent it from jumping up and down
while testing the motor.
1. Disconnect the battery negative cable from the battery.
2. Disconnect the battery positive cable from the battery.
3. Disconnect the leads from the starter B terminal.
4. Remove the starter from the engine.
5. Connect a jumper lead from the starter C terminal (1) to the
battery positive terminal (2).
6. Connect a jumper lead momentarily between the starter’s body
and the battery negative terminal (3).
7. If the motor does not run, starter is failure.
Repair or replace the starter.
■ NOTE
• B terminal : It is the terminal which connects the cable from
the battery to the starter.
• C terminal : It is the terminal which connects the cable from
the motor to the magnet switch.
(1) C Terminal [A] Electromagnetic Drive Type
(2) Positive Terminal [B] Planetary Gear Reduction Type
(3) Negative Terminal
W1024938
Magnetic Switch Test
1. Disconnect the battery negative cable from the battery.
2. Disconnect the battery positive cable from the battery.
3. Disconnect the leads from the starter B terminal.
4. Remove the starter from the engine.
5. Connect a jumper lead from the starter S terminal (1) to the
battery positive terminal (2).
6. Connect a jumper lead momentarily between the starter’s body
and the battery negative terminal (3).
7. If the pinion gear does not pop out, the magnetic switch is failure.
Repair or replace the starter.
■ NOTE
• B terminal : It is the terminal which connects the cable from
the battery to the starter.
• S terminal : It is the terminal which connects the cable from
the starter switch to the magnet switch.
(1) S Terminal [A] Electromagnetic Drive Type
(2) Positive Terminal [B] Planetary Gear Reduction Type
(3) Negative Terminal
W1024939

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Magnet Switch Continuity Test

1. Check the continuity across the C terminal (1) and the B terminal
(2) with a circuit tester, pushing in the plunger.
2. If not continuous or if a certain value is indicated, replace the
magnet switch.
(1) C Terminal [A] Electromagnetic Drive Type
(2) B Terminal [B] Planetary Gear Reduction Type
W1024940

No-load Dynamo Output

1. Disconnect the lead wires from the dynamo.
2. Start the engine and operate the dynamo at the specified speed.
3. Measure the output voltage with a volt meter.
If the measurement is not within the specified values, replace the
dynamo.
AC 20 V or more at
No-load output voltage Factory spec.
5200 min-1 (rpm)
W1021164

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Continuity across Regulator’s Terminals

1. Measure with a circuit tester according to the list below.
■ NOTE
• For this test, use only Analog Meter and do not use a high
voltage tester such as a MΩ meter.
• This check sheet shows the results of the test conducted by
using the “Sanwa-made tester SP-10 and SP-15D” (Analog
Meter).
• Use of other testers than those above may show different
measured results. Ω shall be used as the unit for the
measuring range.
• The judgement should be as below table.
“ON” if the indicator moves, otherwise “OFF”.
■ Check Table (★ : ON, ✩ : OFF)
Tester + Code colors
Terminal
Tester − Blue Black Blue Green Yellow Red
Terminal
Blue ✩ ✩ ✩ ✩ ★
Black ✩ ✩ ✩ ✩ ✩

Code Blue ✩ ✩ ✩ ✩ ★
colors Green ✩ ✩ ✩ ✩ ✩
Yellow ★ ★ ★ ✩ ★
Red ✩ ✩ ✩ ✩ ✩

(1) Blue (4) Green

(2) Black (5) Yellow
(3) Blue (6) Red
W1021509
Regulating Voltage
1. Complete the charging circuit with a fully charged battery and
operate the dynamo at the specified speed.
2. Measure the output voltage with a volt meter.
3. If the measurement is not within the specified values, replace the
dynamo.
Regulating output 14 to 15 V at
Factory spec.
voltage 5200 min-1 (rpm)
W1022299

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Alternator on Unit Test

(Before testing)
• Before alternator on unit test, check the battery terminal
connections, circuit connection, fan belt tension, charging
indicator lamp, fuses on the circuit, and abnormal noise from the
alternator.
• Prepare full charged battery for the test.
■ NOTE
• Be careful not to touch the rotating engine parts while
engine is running.
Keep safety distance from the engine rotating parts.
1. Start the engine.
2. When the engine is operating measure the voltage between two
battery terminals. If the voltage is between 13.8 V and 14.8 V,
the alternator is operating normally.
3. If the results of alternator on unit test are not within the
specifications, disassemble the alternator and check the each
component part for finding out the failure. See the
“DISASSEMBLING AND ASSEMBLING” and “SERVICING” for
alternator.
Regulating voltage at no 13.8 to 14.8 V at 25 °C
Factory spec.
load (77 °F)
W1074500
Fuel Cut Off Solenoid
1. Disconnect the connector.
2. Measure the resistance with an ohmmeter between the
connector terminals.
3. If the factory specification is not indicated the solenoid is faulty.
WG972-E2, DF972-E2 :
Approx. 38 Ω at 20 °C
for Gasoline Factory spec.
DF972-E2 : for LPG Approx. 28 Ω at 20 °C

(1) Fuel Cut off Solenoid for Gasoline (2) Fuel Cut off Solenoid for LPG
W1076917

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(7) Electronic Governor

Adjust Governor Lever
1. Loosen the idling speed screw (1).
2. Loosen the governor lever nut (4).
3. Turn the actuator shaft (3) fully counterclockwise.
4. Turn the governor lever (5) fully counterclockwise.
5. Tighten the governor lever nut (4) to the torque value.
9.8 to 11.3 N·m
Tightening torque Governor lever nut 1.00 to 1.15 kgf·m
7.23 to 8.32 ft-lbs

■ NOTE
• Align governor lever (5) with pin hole of actuator shaft (A) and
tighten nut (4).
• When starter switch turned on, the actuator will be in position
control at the configured minimum position.
(1) Idle Adjust Screw (5) Governor Lever
(2) Actuator
(3) Actuator shaft A : Setting Position
(4) Governor Lever Nut

Adjust Throttle Lever

CAUTION
• Do not overrunning the engine because the electronic
governor dos not operate.
• The adjustment of the idle speed due to this process is not
an adjustment of the final product.
1. Disconnect actuator connector (1).
2. Start the engine while holding the throttle lever (2) at the idle
position by finger.
3. Adjust the engien speed with the idle adjust screw (3) to 1200
rpm.
■ NOTE
• An electornic governor controls the engine speed between
1500 rpm and 3600 rpm though it depends on the
applications.
(1) Actuator Connector (3) Idle Adjust Screw
(2) Throttle Lever

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[2] DISASSEMBLING AND ASSEMBLING

■ IMPORTANT
• When reassembling, replace all of the O-rings and gaskets by new ones.
• When disassembling the LPG engine after completely consuming the fuel in piping.
(1) Draining Coolant and Engine Oil
Draining Coolant

CAUTION
• Never remove radiator cap while operating or immediately
after stopping. Otherwise, hot water will spout out from the
radiator. Wait for more than ten minutes to cool the radiator,
before opening the cap.
1. Prepare a bucket. Open the coolant drain cock.
(1) Coolant Drain Cock
W1023496

Draining Engine Oil

1. Start and warm up the engine for approx. 5 minutes.
2. Place an oil pan underneath the engine.
3. Remove the drain plug (1) to drain oil.
4. After draining, screw in the drain plug.
(When refilling)
• Fill the engine oil up to the upper line on the dipstick (2).
■ IMPORTANT
• When using an oil of different maker or viscosity from the
previous one, remove all of the old oil.
• Never mix two different types of oil.
• Engine oil should have properties of API classification SH.
• Use the proper SAE Engine Oil according to ambient
temperature.
Above 25 °C (77 °F) SAE30 or SAE10W-30
0 °C to 25 °C (32 °F to 77 °F) SAE20 or SAE10W-30
Below 0 °C (32 °F) SAE10W or SAE10W-30

3.4 L
Engine oil capacity
3.59 U.S.qts

32.4 to 37.3 N·m

Tightening torque Drain plug 3.3 to 3.8 kgf·m
23.9 to 27.5 ft-lbs

(1) Drain Plug (2) Dipstick

W1023464

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(2) External Components

Alternator, Starter and Others
1. Remove the air cleaner and muffler.
2. Remove the cooling fan (1), fan pulley and fan belt (2).
3. Remove the alternator.
4. Remove the starter.
(When reassembling)
• Check to see that there are no cracks on the belt surface.
■ IMPORTANT
• After reassembling the fan belt, be sure to adjust the fan belt
tension.
• Do not confuse the direction of the fan.
(1) Cooling Fan (2) Fan Belt
W1049622

Fuel Line
1. Disconnect the gasoline hose from the connector (1).
(1) Gasoline Hose Connector
W1125277

LPG Hose and Water Hose (DF972-E2)

CAUTION
• Vent the air of the water passage of vaporizer (5) after
detaching the water hose (2).
1. Disconnect the LPG hose from the connector (1).
2. Disconnect the water hose (2).
3. Disconnect the vapor hose (3) and vacuum lock hose (4).
4. Remove the vaporizer (5) (if necessary).
■ IMPORTANT
• When disassembling the fuel system, make sure that the fuel
valve is closed.
(When reassembling)
• Bleed the vaporizer after supplying coolant.
(1) LPG Hose Connector (4) Vacuum Lock Hose
(2) Water Hose (5) Vaporizer
(3) Vapor Hose
W1125469

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Carburetor (Mechanical Governor)

1. Disconnect the connector of LPG solenoid (for DF972) (4) and
the connector of gasoline solenoid (3).
2. Disconnect the breather hose (4).
3. Remove the air cleaner flange (2) and air cleaner gasket.
4. Disconnect governor rod (6) from carburetor (7) and remove the
carburetor (7).
5. Remove the carburetor flange and gasket.
■ NOTE
• Do not bend the governor rod (6), when disassembling and
assembling the carburetor.
• Do not stretch the governor rod spring (5) when
disassembling and assembling the carburetor.
23.5 to 27.5 N·m
Tightening torque Carburetor mounting nut 2.4 to 2.8 kgf·m
17.4 to 20.2 ft-lbs

(1) Breather Hose (5) Governor Rod spring

(2) Air Cleaner Flange (6) Governor Rod
(3) Gasoline Solenoid Connector (7) Carburetor
(4) LPG Solenoid Connector
W1126561

Governor Lever and Carburetor (Electronic Governor)

1. Disconnect the connector of LPG solenoid (for DF972) and the
connector of gasoline solenoid.
2. Loosen the governor lever nut.
3. Remove the governor lever (7) with governor rod (5) and
governor spring (6).
4. Disconnect the breather hose (3).
5. Remove the air cleaner flange (2) and air cleaner gasket.
6. Remove the carburetor (4).
7. Remove the carburetor flange (8) and gasket.
■ NOTE
• Do not bend the governor rod (5), when disassembling and
assembling the carburetor.
• Do not stretch the governor rod spring (6) when
disassembling and assembling the carburetor.
23.5 to 27.5 N·m
Tightening torque Carburetor mounting nut 2.4 to 2.8 kgf·m
17.4 to 20.2 ft-lbs

(1) Actuator (5) Governor Rod

(2) Air Cleaner Flange (6) Governor Spring
(3) Breather Hose (7) Governor Lever
(4) Carburetor (8) Carburetor Flange
W1128201

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Adjust Governor Lever (Electronic Governor)

1. Loosen the idling speed screw (1).
2. Loosen the governor lever nut (4).
3. Turn the actuator shaft (3) fully counterclockwise.
4. Turn the governor lever (5) fully counterclockwise.
5. Tighten the governor lever nut (4) to the torque value.
9.8 to 11.3 N·m
Tightening torque Governor lever nut 1.00 to 1.15 kgf·m
7.23 to 8.32 ft-lbs

■ NOTE
• Align governor lever (5) with pin hole of actuator shaft (A)
and tighten nut (4).
• When starter switch turned on, the actuator will be in
position at the configured minimum position.
(1) Idle Adjust Screw (5) Governor Lever
(2) Actuator
(3) Actuator shaft A : Setting Position
(4) Governor Lever Nut

Adjust Throttle Lever (Electronic Governor)

CAUTION
• Hold the throttle lever (2) by finger in the direction of the
engine speed reduction so as not to overrun.
• The adjustment of the idle speed due to this process is not
an adjustment of the final product.
1. Disconnect the connector (1) from actuator.
2. Start the engine while holding the throttle lever (2) at the idle
position by hand.
3. Adjust the engien speed with the idle adjust screw (3) to 1200
rpm.
■ NOTE
• An electornic governor controls the engine speed between
1500 rpm and 3600 rpm though it depends on the
applications.
(1) Connector (3) Idle Adjust Screw
(2) Throttle Lever
W1129226

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Actuator (Electronic Governor)

1. Remove the actuator mounting screw (1).
2. Remove the actuator (2).
3. Remove the actuator flange screw (4).
4. Remove the actuator flange (3).
4.9 to 5.4 N·m
Tightening torque Actuator mounting screw 0.45 to 0.55 kgf·m
3.6 to 4.0 ft-lbs

9.8 to 11.3 N·m

Tightening torque Actuator flange screw 1.00 to 1.15 kgf·m
7.23 to 8.32 ft-lbs

CAUTION
• All electronic equipment is static-sensitive, some
components more than others.
• To protect these components from static damage, you must
take special precautions to minimize or eliminate
electrostatic discharges.
(1) Actuator Mounting Screw (3) Actuator Flange
(2) Actuator (4) Actuator Flange Screw
W1129613
Governor Lever
1. Disconnect the governor rod (2) and rod spring (1) from governor
lever (3).
2. Disconnect the governor spring (4) from governor lever.
3. Loosen the governor lever nut (6).
4. Remove the governor lever (3) from governor lever shaft (5).
(When reassembling)
• Loosen the governor lever nut (6).
• Set the throttle valve to the fully “OPEN” position with the
governor lever (3), turn the groove on the governor lever shaft (5)
fully clockwise with a screwdriver (to open the governor
completely), and then tighten the nut (6) in this position.
23.5 to 27.5 N·m
Tightening torque Governor lever nut 2.4 to 2.8 kgf·m
17.4 to 20.2 ft-lbs

■ IMPORTANT
• After assembly of engine is completed, the adjustment of
governor is executed.
• Insert the governor lever to the position 2 mm (A) away from
the governor lever shaft end.
(1) Governor Rod Spring A : Open Direction
(2) Governor Rod B : 2 mm (0.079 in.)
(3) Governor Lever
(4) Governor Spring
(5) Governor Lever Shaft
(6) Governor Lever Nut
W1025983

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Ignition Coil and Spark Plug

1. Disconnect the plug cap (1).
2. Disconnect the connector of ignition coil (3).
3. Remove the ignition coil (2).
A : for No. 1 cylinder
B : for No. 2 cylinder
C : for No. 3 cylinder
4. Remove the spark plug (4).
(1) Plug Cap (3) Ignition Coil Connector
(2) Ignition Coil (4) Spark Plug
W1078106

(3) Cylinder Head, Valves and Oil Pan

Cylinder Head Cover
1. Remove the head cover screws (1).
2. Remove the cylinder head cover (2).
3. Remove the intake manifold (3).
(When reassembling)
• Check to see if the cylinder head cover gasket is not defective.
6.86 to 11.3 N·m
Tightening torque Cylinder head cover screw 0.7 to 1.15 kgf·m
5.1 to 8.3 ft-lbs

(1) Head Cover Screws (3) Intake Manifold

(2) Cylinder Head Cover
W1049737

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Rocker Arm and Push Rod

1. Remove the rocker arm bracket screws (1).
2. Detach the rocker arm assembly (2).
3. Remove the push rods (3).
(When reassembling)
• When putting the push rods (3) onto the tappets (4), check to see
if their ends are properly engaged with the dimples.
■ IMPORTANT
• After installing the rocker arm, be sure to adjust the valve
clearance.
9.8 to 11.3 N·m
Tightening torque Rocker arm bracket screw 1.00 to 1.15 kgf·m
7.2 to 8.3 ft-lbs

(1) Rocker Arm Bracket screws (3) Push Rod

(2) Rocker Arm Assembly (4) Tappet
W1050212

Cylinder Head
1. Loosen the pipe clamps (1), and remove the water return hose
(2).
2. Remove the cylinder head screw in the order of (n) to (a).
3. Lift up the cylinder head to detach.
4. Remove the cylinder head gasket.
(When reassembling)
• Replace the cylinder head gasket with a new one.
• Tighten the cylinder head screws after applying sufficient oil.
• Tighten the cylinder head screws in order of (a) to (n).
• Tighten them uniformly, or the head may deform in the long run.
37.3 to 42.2 N·m
Tightening torque Cylinder head screw 3.8 to 4.3 kgf·m
27.5 to 31.1 ft-lbs

(1) Hose Clamp A : Gear Case Side

(2) Water Return Hose (n) to (a) : To Loosen
(a) to (n) : To Tighten
W1025645

Tappets
1. Remove the tappets (1) from the crankcase.
(When reassembling)
• Visually check the contact between tappets and cams for proper
rotation. If defect is found, replace tappets.
• Before installing the tappets, apply engine oil thinly around them.
■ IMPORTANT
• Do not change the combination of tappet and tappet guide.
(1) Tappet
W10209700

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Valves
1. Remove the valve caps (2).
2. Remove the valve spring collet (3), pushing the valve spring
retainer (4) by valve spring replacer (1).
3. Remove the valve spring retainer (4), valve spring (5) and valve
stem seal (6).
4. Remove the valve (7).
(When reassembling)
• Wash the valve stem and valve guide hole, and apply engine oil
sufficiently.
• After installing the valve spring collets, lightly tap the stem to
assure proper fit with a plastic hammer.
• Install a new stem seal on the valve guide (10) vertically with a jig
(9) when insert the stem seal (6). (See page G-24: "Valve Stem
Seal Replacing Tool".)
■ IMPORTANT
• Be sure stem seal (6) seats firmly against groove (8) on valve
guide.
• Use care to prevent damage to lip of stem seal and valve
stem when detach the valve spring collet by compressing
the valve spring.
• Do not change the combination of valve and valve guide.
(1) Valve Spring Replacer (6) Valve Stem Seal
(2) Valve Cap (7) Valve
(3) Valve Spring Collet (8) Groove of Valve Guide
(4) Valve Spring Retainer (9) Jig
(5) Valve Spring (10) Valve Guide
W10211070

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Oil Pan and Oil Strainer

1. Remove the oil pan mounting screws (1).
2. Remove the oil pan (2) by lightly tapping the rim of the pan with
a wooden hammer.
3. Remove the oil strainer (3).
(When reassembling)
• After cleaning the oil strainer, check to see that the filter mesh in
clean, and install it.
• Visually check the O-ring (4), apply engine oil, and install it.
• Securely fit the O-ring to the oil strainer.
• To avoid uneven tightening, tighten oil pan mounting screws in
diagonal order form the center.
• Using the hole (5) numbered “3”, install the oil strainer by
mounting screw
■ IMPORTANT
• Scrape off the old adhesive completely. Wipe the sealing
surface clean. Now apply new adhesive 3 to 5 mm (0.12 to
0.20 in.) thick all over the contact surface. Apply the
adhesive also on the center of the flange as well as on the
inner wall of each bolt hole.
• Cut the nozzle of the “liquid gasket” (Three Bond 1207D or
equivalent) container at its second notch. Apply “liquid
gasket” about 5 mm (0.20 in.) thick.
Within 20 minutes after the application of fluid sealant,
reassemble the components. Wait then for about 30
minutes, and pour oil in the crankcase.
(1) Oil Pan Mounting Screw (4) O-ring
(2) Oil Pan (5) Hole Numbered “3”
(3) Oil Strainer
W10236610

(4) Thermostat
Thermostat Assembly
1. Remove the thermostat cover mounting screws (1), and remove
the thermostat cover (2).
2. Remove the thermostat assembly (4).
(When reassembling)
• Apply a liquid gasket (Three Bond 1215 or equivalent) only at the
thermostat cover side of the gasket (3).
(1) Thermostat Cover Mounting Screw (3) Thermostat Cover Gasket
(2) Thermostat Cover (4) Thermostat Assembly
W1072747

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(5) Timing Gear, Camshaft and Fuel Camshaft

Speed Control Plate
1. Remove the screws (1) and separate the speed control plate (2).
(When reassembling)
• Remove the speed control plate (for mechanical governor only)
(2) and make sure that the governor lever shaft (3) is correctly set
in the governor fork (4).
■ NOTE
• Electronic governor specification engine has modefied from
speed control plate to cover plate.
(1) Screws and Copper Washers (3) Governor Lever Shaft
(2) Speed Control Plate (4) Governor Fork
W1148604

Fan Drive Pulley

1. Secure the flywheel to keep it from turning.
2. Remove the fan drive pulley screw.
3. Draw out the fan drive pulley with a puller.
(When reassembling)
• Install the pulley to the crankshaft, aligning the mark (1) on them.
• Apply engine oil to the fan drive pulley retaining screws. And
tighten them.
98.1 to 107.9 N·m
Tightening torque Fan drive pulley screw 10.0 to 11.0 kgf·m
72.3 to 79.6 ft-lbs

(1) Alignment Mark

W1028534
Gear Case
1. Remove the screw (1) of inside the gear case and outside
screws.
2. Remove the gear case (2).
(When reassembling)
• Apply a liquid gasket (Three Bond 1215 or equivalent) to both
sides of the gear case gasket.
• Be sure to set three O-rings inside the gear case.
(1) Screw (Inside) (2) Gear Case
W1029858

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Water Pump Assembly

1. Remove the water pump assembly from the gear case cover.
(When reassembling)
• Apply a liquid gasket (Three Bond 1215 or equivalent) to both
sides of gasket (3).
(1) Water Pump Flange (3) Water Pump Gasket
(2) Water Pump Assembly
W1150960

Idle Gear
1. Remove the external snap ring (3), the collar (2) and the idle gear
(1).
2. Remove the idle gear shaft mounting screws (4).
3. Remove the idle gear shaft (5).
(When reassembling)
• Apply engine oil to the idle gear shaft mounting screw (4). And
tighten them.
• Install the idle gear, aligning the mark (6) on the gears referring
to the photo.
9.8 to 11.3 N·m
Idle gear shaft mounting
Tightening torque 1.00 to 1.15 kgf·m
screw
7.2 to 8.3 ft-lbs

(1) Idle Gear (4) Idle Gear Shaft Mounting Screw

(2) Idle Gear Collar (5) Idle Gear Shaft
(3) External Snap Ring (6) Alignment Mark
W1030437

Camshaft
1. Remove the camshaft mounting screws (1) and draw out the
camshaft with gear (2) on it.
(When reassembling)
• When install the camshaft, apply engine oil to the camshaft
journals.
• Apply engine oil to the camshaft mounting screws. And tighten
them.
(1) Camshaft Mounting Screw (2) Camshaft Gear
W1030808

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Fuel Camshaft
1. Remove the retaining plate (4).
2. Remove the fork lever holder (for mechanical governor only)
mounting screws (6), then draw out the injection pump gear (1)
and fuel camshaft (5) with the governor fork assembly.
■ NOTE
• Electronic governor specification engine does not install the
fork lever (3) and governor assembly.
(1) Injection Pump Gear (4) Retaining Plate
(2) Governor Sleeve (5) Fuel Camshaft
(3) Fork Lever (6) Fork Lever Holder Mounting Screw
W10178820

Oil Pump and Crankshaft Gear

1. Remove the oil pump gear (6).
2. Remove the oil pump (5).
3. Remove the collar (4), O-ring (3) and crankshaft oil slinger (2).
(When reassembling)
• Install the collar (4) after aligning the marks on the gear.
(1) Crankshaft Gear (4) Crankshaft Collar
(2) Crankshaft Oil Slinger (5) Oil Pump
(3) O-ring (6) Oil Pump Gear

W10180290

(6) Piston and Connecting Rod

Connecting Rod Cap
1. Remove the connecting rod caps (1) using a bihexagonal 8 mm
socket.
(When reassembling)
• Align the marks (a) with each other. (Face the marks toward the
intake manifold.)
• Apply engine oil to the connecting rod screws and lightly screw it
in by hand, then tighten it to the specified torque.
If the connecting rod screw won’t be screwed in smoothly, clean
the threads.
If the connecting rod screw is still hard to screw in, replace it.
26.5 to 30.4 N·m
Tightening torque Connecting rod screw 2.7 to 3.1 kgf·m
19.5 to 22.4 ft-lbs

(1) Connecting Rod Cap (a) Mark

W10275480

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Piston
1. Turn the flywheel and bring the piston to top dead center.
2. Draw out the piston upward by lightly tapping it from the bottom
of the crankcase with the grip of a hammer.
3. Draw out the other pistons after the same method as above.
(When reassembling)
• Before inserting the piston into the cylinder, apply enough engine
oil to the piston.
• When inserting the piston into the cylinder, face the mark on the
connecting rod to the fuel camshaft.
• When inserting the piston into the cylinder, place the gap (C) of
the top compression ring on the opposite side of the slant portion
(1), and stagger the gaps (A), (E) of the second compression ring
and spacer making 2.09 rad (120 °) from the gap of the top
compression ring. Further, stagger the gaps (D), (B) of the upper
and lower side rail making 1.57 rad (90 °) from the gap of the
spacer.
■ IMPORTANT
• Do not change the combination of cylinder and piston. Make
sure of the position of each piston by marking. For example,
mark “1” on the No. 1 piston.
• When installing the piston into the cylinder, place the gaps
of all of the piston rings as shown in the figure.
• Carefully insert the piston using a piston ring compressor
(1). Otherwise, their chrome-plated section may be
scratched, causing trouble inside the cylinder.
(1) Piston Ring Compressor (D) Side Rail Gap
(E) Spacer Gap
(A) Second Compression Ring Gap
(B) Side Rail Gap (a) 2.09 rad (120°)
(C) Top Compression Ring Gap (b) 1.57 rad (90 °)
W10277450

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Piston Ring and Connecting Rod

1. Remove the piston rings using a piston ring tool.
2. Remove the piston pin (10), and separate the connecting rod (8)
from the piston (7).
(When reassembling)
• When installing the second compression ring (2), assemble the
rings so that the manufacturer’s mark (11) near the gap faces the
top of the piston.
• Apply engine oil to the piston pin.
• When installing the connecting rod to the piston, immerse the
piston in 80 °C (176 °F) oil for 10 to 15 minutes and insert the
piston pin to the piston.
• When installing the connecting rod to the piston, align the mark
(9) on the connecting rod to the plug recess (6).
■ IMPORTANT
• Mark the same number on the connecting rod and the piston
so as not to change the combination.
(1) Top Ring (7) Piston
(2) Second Ring (8) Connecting Rod
(3) Side Rail (9) Mark
(4) Spacer (10) Piston Pin
(5) Piston Pin Snap ring (11) Manufacturer's Mark
(6) Plug Recess
W10281670

(7) Crankshaft
Flywheel
1. Secure the flywheel to keep it from turning using a flywheel
stopper.
1. Remove all flywheel screws (1) and then remove the flywheel (2).
(When reassembling)
• Align the “1TC” mark (a) on the outer surface of the flywheel
horizontally with the alignment mark (b) on the rear end plate.
Now fit the flywheel in position.
• Apply engine oil to the threads and the undercut surface of the
flywheel screw and fit the screw.
53.9 to 58.8 N·m
Tightening torque Flywheel screw 5.5 to 6.0 kgf·m
39.8 to 43.4 ft-lbs

(1) Flywheel Screw (a) 1TC Mark

(2) Flywheel (b) Alignment Mark
W1060354

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Bearing Case Cover

■ NOTE
• Remove the bearing case cover mounting screws. First, remove
inside screws (1) and then outside screws (2).
2. Remove the bearing case cover (6).
(When reassembling)
• Fit the bearing case gasket (3) and the bearing case cover gasket
(4) with correct directions.
• Install the bearing case cover (6) to position the casting mark
"UP" (a) on it upward.
• Apply engine oil to the oil seal (5) lip and take care that it is not
rolled when installing.
• Tighten the bearing case cover mounting screws with even force
on the diagonal line.
9.8 to 11.3 N·m
Bearing case cover
Tightening torque 1.00 to 1.15 kgf·m
mounting screw
7.2 to 8.3 ft-lbs

(1) Bearing Case Cover Mounting Screw (5) Oil Seal

(Inside) (6) Bearing Case Cover
(2) Bearing Case Cover Mounting Screw
(Outside) (a) Top Mark "UP"
(3) Bearing Case Gasket (b) Upside
(4) Bearing Case Cover Gasket
W1060482

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Crankshaft Assembly
1. Remove the main bearing case screw 2 (1).
2. Turn the crankshaft to set the crankpin of the third cylinder to the
bottom dead center. Then draw out the crankshaft until the
crankpin of the second cylinder comes to the center of the third
cylinder.
3. Turn the crankshaft by 2.09 rad (120 °) counterclockwise to set
the crankpin of the second cylinder to the bottom dead center.
Draw out the crankshaft until the crankpin of the first cylinder
comes to the center of the third cylinder.
4. Repeat the above steps to draw out all the crankshaft.
(When reassembling)
• Clean the oil passage of the crankshaft with compressed air.
• Install the crankshaft assembly, aligning the screw hole of main
bearing case screw 2 with the screw hole of crankcase.
• When tightening the main bearing case 2, apply oil to the main
bearing case screw 2 (1) and screw by hand before tightening the
specific torque. If not smooth to screw by hand, align the screw
holes between the crankcase and the main bearing case.
26.5 to 30.4 N·m
Tightening torque Main bearing case screw 2 2.7 to 3.1 kgf·m
19.5 to 22.4 ft-lbs

(1) Main Bearing Case Screw 2 A : Cut Place for Removing and
Installing the Crankshaft
W1031360

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Main Bearing Case Assembly

1. Remove the two main bearing case screws 1 (4), and remove the
main bearing case assembly 1 (1), being careful with crankshaft
bearing 3 (5) (9).
2. Remove the main bearing case assembly 2 (2) and the main
bearing case assembly (3) as above. Keep in mind, however,
that the thrust bearing (8) is installed in the main bearing case
assembly (3).
(When reassembling)
• Clean the oil passage in the main bearing cases.
• Apply clean engine oil to the bearings.
• Install the main bearing case assemblies in original positions.
Since diameters of main bearing cases vary, install them in order
of marking (b) from the gear case side. (Refer to the figure.).
• Be careful not to confuse the top and bottom of the crankshaft
bearing 3 (5) (9). (Install the bearing with the oil groove (c) up.)
• Match the alignment numbers (a) on the main bearing case
assembly 1.
• Do the same for the main bearing case assembly 2 (2) and the
main bearing case assembly (3) too.
• When installing the main bearing case 1 and 2, face the mark
“FLYWHEEL” to the flywheel.
• Install the thrust bearing (8) with its oil groove facing outward.
• Confirm that the main bearing case moves smoothly after
tightening the main bearing case screw 1 to the specified torque.
12.7 to 15.7 N·m
Tightening torque Main bearing case screw 1 1.3 to 1.6 kgf·m
9.4 to 11.6 ft-lbs

(1) Main Bearing Case Assembly 1 (a) Alignment Number

(2) Main Bearing Case Assembly 2 (b) Marking (1 or 2)
(3) Main Bearing Case Assembly (c) Oil Groove
(4) Main Bearing Case Screw 1
(5) Crankshaft Bearing 3
(Upper, with Oil Groove)
(6) Crankshaft Bearing 2
(Upper, with Oil Groove)
(7) Crankshaft Bearing 2 (Lower)
(8) Thrust Bearing
(9) Crankshaft Bearing 3 (Lower)
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(8) Starter
(1) Solenoid Switch mounting Nut
(2) Starter Drive Housing
(3) Drive lever
(4) Gasket
(5) Solenoid Switch
(6) C Terminal Nut
(7) Snap Ring
(8) Overrunning Clutch
(9) Armature
(10) Brush Spring
(11) Connecting Lead
(12) Rear End Frame
(13) Gasket
(14) Break Spring
(15) Break Shoe
(16) End Frame Cap
(17) Screw
(18) Yoke
(19) Brush
(20) Brush Holder
(21) Through Bolt
W1224079

1. Unscrew the C terminal nut (6), and disconnect the connecting lead (11).
2. Unscrew the solenoid switch mounting nuts (1), and remove the solenoid switch (5).
3. Remove the end frame cap (16).
4. Remove the break shoe (15), break spring (14) and gasket (13).
5. Unscrew the through bolts (21), and remove the rear end frame (12).
6. Remove the brush from the brush holder while holding the spring up.
7. Remove the brush holder (20).
8. Draw out the yoke (18) from the starter drive housing (2).
9. Draw out the armature (9) with the drive lever (3).
■ NOTE
• Do not damege to the brush and commutator.
(When reassembling)
• Apply grease (DENSO.CO.LTD. No. 50 or its equivalent) to the parts indicated in the figure.
- Joint of solenoid switch (a)
- Bushing (b)
- Drive lever (c)
- Collar (d)
- Teeth of pinion gear (e)
- Armature shaft (f)

5.9 to 11.8 N·m

Tightening torque C Terminal Nut 0.6 to 1.2 kgf·m
4.3 to 8.7 ft-lbs

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[3] SERVICING
(1) Cylinder Head and Valves
Cylinder Head Surface Flatness
1. Clean the cylinder head surface.
2. Place a straightedge on the cylinder head’s four sides and two
diagonal as shown in the figure.
Measure the clearance with a feeler gauge.
3. If the measurement exceeds the allowable limit, correct it with a
surface grinder.
■ IMPORTANT
• Be sure to check the valve recessing after correcting.
Cylinder head surface 0.05 mm
Allowable limit
flatness 0.0020 in.
W1061323

Cylinder Head Flaw

1. Prepare an air spray red check.
2. Clean the surface of the cylinder head with the detergent (2).
3. Spray the cylinder head surface with the red permeative liquid
(1). Leave it five to ten minutes after spraying.
4. Wash away the red permeative liquid on the cylinder head
surface with the detergent (2).
5. Spray the cylinder head surface with the white developer (3).
6. If flawed, it can be identified as red marks.
(1) Red Permeative Liquid (3) White Developer
(2) Detergent

W1076542

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Valve Recessing
1. Clean the cylinder head, the valve face and seat.
2. Insert the valve into the valve guide.
3. Measure the valve recessing with a depth gauge.
4. If the measurement exceeds the allowable limit, replace the
valve.
5. If it still exceeds the allowable limit after replacing the valve,
replace the cylinder head.
0.10 (protrusion) to
0.10 (recessing) mm
Factory spec.
Valve recessing (Intake 0.0039 (protrusion) to
and Exhaust) 0.0039 (recessing) in.
0.30 (recessing) mm
Allowable limit
0.0118 (recessing) in.

(1) Cylinder Head Surface (A) Recessing

(B) Protrusion

W1061543

Clearance between Valve Stem and Valve Guide

1. Remove carbon from the valve guide section.
2. Measure the valve stem O.D. with an outside micrometer.
3. Measure the valve guide I.D. with a small hole gauge, and
calculate the clearance.
4. If the clearance exceeds the allowable limit, replace the valves.
If it still exceeds the allowable limit, replace the valve guide.
0.030 to 0.057 mm
Clearance between Factory spec.
0.00118 to 0.00224 in.
valve stem and valve
guide 0.10 mm
Allowable limit
0.0039 in.

5.968 to 5.980 mm
Valve stem O.D. Factory spec.
0.23496 to 0.23543 in.
6.010 to 6.025 mm
Valve guide I.D. Factory spec.
0.23661 to 0.23720 in.
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Replacing Valve Guide

(When removing)
1. Press out the used valve guide using a valve guide replacing tool.
(When installing)
1. Clean a new valve guide and valve guide bore, and apply engine
oil to them.
2. Press in a new valve guide using a valve guide replacing tool.
3. Ream precisely the I.D. of the valve guide to the specified
dimension.
Valve guide I.D. 6.010 to 6.025 mm
Factory spec.
(Intake and exhaust) 0.23661 to 0.23720 in.

■ IMPORTANT
• Do not hit the valve guide with a hammer during
replacement.
(A) When Removing (B) When Installing

W10314690

Valve Seating
1. Coat the valve face lightly with prussian blue and put the valve on
its seat to check the contact.
2. If the valve does not seat all the way around the valve seat or the
valve contact is less than 70 %, correct the valve seating as
follows.
3. If the valve contact does not comply with the reference value,
replace the valve or correct the contact of valve seating.
2.12 mm
Valve seat width Factory spec.
0.0835 in.

(1) Correct (3) Incorrect

(2) Incorrect
W10282190

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Correcting Valve and Valve Seat

■ NOTE
• Before correcting the valve and seat, check the valve stem
and the I.D. of valve guide section, and repair them if
necessary.
• After correcting the valve seat, be sure to check the valve
recessing.

1) Correcting Valve
1. Correct the valve with a valve refacer.
0.785 rad
Valve face angle Factory spec.
45 °

2) Correcting Valve Seat

1. Slightly correct the seat surface with a 0.785 rad (45 °) valve seat
cutter.
2. Fitting the valve, check the contact position of the valve face and
seat surface with prussian blue. (Visual check) [If the valve has
been used for a long period, the seat tends to come in contact
with the upper side of the valve face.]
3. Grind the upper surface of the seat with a 0.262 rad (15 °) valve
seat cutter until the valve seat touches to the center of the valve
face (so that (a) equals (b) as shown in the figure.)
4. Grind the seat with a 0.785 rad (45 °) valve seat cutter again, and
visually recheck the contact between the valve and seat.
5. Repeat steps 3 and 4 until the correct contact is achieved.
6. Continue lapping until the seated rate becomes more than 70 %
of the total contact area.
0.785 rad
Valve seat angle Factory spec.
45 °

(1) Valve Seat Cutter (a) Identical Dimensions

(b) Valve Seat Width
(A) Check Contact (c) 0.262 rad (15 °)
(B) Correct Seat Width (d) 0.785 rad (45 °)
(C) Check Seat Surface
(D) Check Contact
W1028220
Valve Lapping
1. Apply compound evenly to the valve lapping surface.
2. Insert the valve into the valve guide. Lap the valve onto its seat
with a valve flapper or screwdriver.
3. After lapping the valve, wash the compound away and apply oil,
then repeat valve lapping with oil.
4. Apply prussian blue to the contact surface to check the seated
rate. If it is less than 70 %, repeat valve lapping again.
■ IMPORTANT
• When valve lapping is performed, be sure to check the valve
recessing and adjust the valve clearance after assembling
the valve.
W1061709

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Free Length and Tilt of Valve Spring

1. Measure the free length (B) of valve spring with vernier calipers.
If the measurement is less than the allowable limit, replace it.
2. Put the spring on a surface plate, place a square on the side of
the spring.
3. Check to see if the entire side is in contact with the square.
Rotate the valve spring and measure the maximum tilt (B).
If the measurement exceeds the allowable limit, replace it.
4. Check the entire surface of the valve spring for scratches.
If there is any defect, replace it.
1.0 mm
Tilt (A) Allowable limit
0.047 in.

31.3 to 31.8 mm
Factory spec.
1.232 to 1.252 in.
Free length (B)
28.4 mm
Allowable limit
1.118 in.

(A) Tilt (B) Free length

W1063303
Valve Spring Setting Load
1. Place the valve spring on a tester and compress it to the same
length it is actually compressed in the engine.
2. Read the compression load on the gauge.
3. If the measurement is less than the allowable limit, replace it.
64.7 N / 27.0 mm
Factory spec. 6.6 kgf / 27.0 mm
Setting load / setting 14.6 lbs / 1.063 in.
length 54.9 N / 27.0 mm
Allowable limit 5.6 kgf / 27.0 mm
12.3 lbs / 1.063 in.
W1063470
Oil Clearance between Rocker Arm and Rocker Arm Shaft
1. Measure the rocker arm shaft O.D. with an outside micrometer.
2. Measure the rocker arm I.D. with an inside micrometer, and then
calculate the oil clearance.
3. If the oil clearance exceeds the allowable limit, replace the rocker
arm and measure the oil clearance again. If it still exceeds the
allowable limit, replace also the rocker arm shaft.
0.016 to 0.045 mm
Oil clearance between Factory spec.
0.00063 to 0.00177 in.
rocker arm and rocker
arm shaft 0.15 mm
Allowable limit
0.0059 in.

10.473 to 10.484 mm
Rocker arm shaft O.D. Factory spec.
0.41232 to 0.41276 in.
10.500 to 10.518 mm
Rocker arm I.D. Factory spec.
0.41339 to 0.41410 in.
W1063697

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Push Rod Alignment

1. Place the push rod on V blocks.
2. Measure the push rod alignment.
3. If the measurement exceeds the allowable limit, replace the push
rod.
0.25 mm
Push rod alignment Allowable limit
0.0098 in.
W10292900

Oil Clearance between Tappet and Tappet Guide Bore

1. Measure the tappet O.D. with an outside micrometer.
2. Measure the I.D. of the tappet guide bore with a cylinder gauge,
and calculate the oil clearance.
3. If the oil clearance exceeds the allowable limit or the tappet is
damaged, replace the tappet.
0.016 to 0.052 mm
Oil clearance between Factory spec.
0.00063 to 0.00205 in.
tappet and tappet guide
bore 0.10 mm
Allowable limit
0.0039 in.

17.966 to 17.984 mm
Tappet O.D. Factory spec.
0.70732 to 0.70803 in.
18.000 to 18.018 mm
Tappet guide bore I.D. Factory spec.
0.70866 to 0.70937 in.
W1063847

(2) Timing Gear, Camshaft

Timing Gear Backlash
1. Set a dial indicator (lever type) with its tip on the gear tooth.
2. Move the gear to measure the backlash, holding its mating gear.
3. If the backlash exceeds the allowable limit, check the oil
clearance of the shafts and the gear.
4. If the oil clearance is proper, replace the gear.
0.043 to 0.124 mm
Factory spec.
Backlash between idle 0.00169 to 0.00488 in.
gear and crank gear 0.15 mm
Allowable limit
0.0059 in.

0.047 to 0.123 mm
Factory spec.
Backlash between idle 0.00185 to 0.00484 in.
gear and cam gear 0.15 mm
Allowable limit
0.0059 in.

0.046 to 0.124 mm
Backlash between idle Factory spec.
0.00181 to 0.00488 in.
gear and injection pump
gear 0.15 mm
Allowable limit
0.0059 in.

0.041 to 0.123 mm
Backlash between oil Factory spec.
0.00161 to 0.00484 in.
pump drive gear and
crank gear 0.15 mm
Allowable limit
0.0059 in.
W1064048

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Idle Gear Side Clearance

1. Set a dial indicator with its tip on the idle gear.
2. Measure the side clearance by moving the idle gear to the front
and rear.
3. If the measurement exceeds the allowable limit, replace the idle
gear collar.
0.20 to 0.51 mm
Factory spec.
0.0079 to 0.0201 in.
Idle gear side clearance
0.80 mm
Allowable limit
0.0315 in.
W1064208
Camshaft Side Clearance
1. Set a dial indicator with its tip on the camshaft.
2. Measure the side clearance by moving the cam gear to the front
and rear.
3. If the measurement exceeds the allowable limit, replace the
camshaft stopper.
0.15 to 0.31 mm
Factory spec.
Camshaft side 0.0059 to 0.0122 in.
clearance 0.50 mm
Allowable limit
0.0197 in.
W1064307
Camshaft Alignment
1. Support the camshaft with V blocks on the surface plate at both
end journals.
2. Set a dial indicator with its tip on the intermediate journal.
3. Measure the camshaft alignment.
4. If the measurement exceeds the allowable limit, replace the
camshaft.
0.01 mm
Camshaft alignment Allowable limit
0.0004 in.
W1064422

Cam Height
1. Measure the height of the cam at its highest point with an outside
micrometer.
2. If the measurement is less than the allowable limit, replace the
camshaft.
26.88 mm
Factory spec.
Cam height of intake 1.0583 in.
and exhaust 26.83 mm
Allowable limit
1.0563 in.
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Oil Clearance of Camshaft Journal

1. Measure the camshaft journal O.D. with an outside micrometer.
2. Measure the cylinder block bore I.D. for camshaft with a inside
micrometer, and calculate the oil clearance.
3. If the clearance exceeds the allowable limit, replace the
camshaft.
0.050 to 0.091 mm
Factory spec.
Oil clearance of 0.00197 to 0.00358 in.
camshaft journal 0.15 mm
Allowable limit
0.0059 in.

32.934 to 32.950 mm
Camshaft journal O.D. Factory spec.
1.29661 to 1.29724 in.
Camshaft bearing I.D.
33.000 to 33.025 mm
(Cylinder block bore Factory spec.
1.29921 to 1.30020 in.
I.D.)
W1064798

Oil Clearance between Idle Gear Shaft and Idle Gear Bushing
1. Measure the idle gear shaft O.D. with an outside micrometer.
2. Measure the idle gear bushings I.D. with an inside micrometer,
and calculate the oil clearance.
3. If the oil clearance exceeds the allowable limit, replace the
bushing.
4. If it still exceeds the allowable limit, replace the idle gear shaft.
0.020 to 0.084 mm
Oil clearance between Factory spec.
0.00079 to 0.00331 in.
idle gear shaft and idle
gear bushing 0.10 mm
Allowable limit
0.0039 in.

19.967 to 19.980 mm
Idle gear shaft O.D. Factory spec.
0.78610 to 0.78661 in.
20.000 to 20.051 mm
Idle gear bushing I.D. Factory spec.
0.78740 to 0.78941 in.
W1064968
Replacing Idle Gear Bushing
(When removing)
1. Press out the used idle gear bushing using an idle gear bushing
replacing tool.
(When installing)
1. Clean a new idle gear bushing and idle gear bore, and apply
engine oil to them.
2. Press in a new bushing using an idle gear bushing replacing tool,
until it is flush with the end of the idle gear.
(A) When Removing (B) When Installing
W10302410

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(3) Piston and Connecting Rod

Piston Pin Bore I.D.
1. Measure the piston pin bore I.D. in both the horizontal and
vertical directions with a cylinder gauge.
2. If the measurement exceeds the allowable limit, replace the
piston.
20.000 to 20.013 mm
Factory spec.
0.78740 to 0.78791 in.
Piston pin bore I.D.
20.05 mm
Allowable limit
0.7894 in.

W1065759
Oil Clearance between Piston Pin and Small End Bushing
1. Measure the O.D. of the piston pin where it contacts the bushing
with an outside micrometer.
2. Measure the small end bushing I.D. with an inside micrometer,
and calculate the oil clearance.
3. If the oil clearance exceeds the allowable limit, replace the
bushing. If it still exceeds the allowable limit, replace the piston
pin.
0.014 to 0.038 mm
Oil clearance between Factory spec.
0.00055 to 0.00150 in.
piston pin and small end
bushing 0.10 mm
Allowable limit
0.0039 in.

20.002 to 20.011 mm
Piston pin O.D. Factory spec.
0.78748 to 0.78783 in.
20.025 to 20.040 mm
Small end bushing I.D. Factory spec.
0.78839 to 0.78897 in.

W1065897
Replacing Small End Bushing
(When removing)
1. Press out the used bushing using a small end bushing replacing
tool. (Refer to "SPECIAL TOOLS".)
(When installing)
1. Clean a new small end bushing and bore, and apply engine oil to
them.
2. Using a small end bushig replacing tool, press in a new bushing
(service parts) taking due care to see that the connecting rod hole
matches the bushing hole.
[Servicing parts dimension]
0.015 to 0.075 mm
Oil clearance between Factory spec.
0.00059 to 0.00295 in.
piston pin and small end
bushing (Spare parts) 0.15 mm
Allowable limit
0.0059 in.

Small end bushing I.D. 20.026 to 20.077 mm

Factory spec.
(Spare parts) 0.78843 to 0.79043 in.

(1) Seam (A) When Removing

(2) Oil Hole (B) When Installing
(C) 0.785 rad (45 °)
W1066057

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Piston Ring Gap

1. Insert the piston ring into the lower part of the cylinder (the least
worn out part) with a piston ring compressor and piston.
2. Measure the ring gap with a feeler gauge.
3. If the measurement exceeds the allowable limit, replace the
piston ring.
Factory 0.15 to 0.35 mm
spec. 0.0059 to 0.0138 in.
Top ring
Allowable 1.25 mm
limit 0.0492 in.
Factory 0.30 to 0.45 mm
spec. 0.0118 to 0.0177 in.
Piston ring gap Second ring
Allowable 1.25 mm
limit 0.0492 in.
Factory 0.20 to 0.70 mm
spec. 0.0079 to 0.0276 in.
Oil ring
Allowable 1.25 mm
limit 0.0492 in.

W1146671
Clearance between Piston Ring and Piston Ring Groove
1. Clean the rings and the ring grooves, and install each ring in its
groove.
2. Measure the clearance between the ring and the groove with a
thickness gauge.
3. If the clearance exceeds the allowable limit, replace the piston
ring.
4. If the clearance still exceeds the allowable limit with new ring,
replace the piston.
Factory 0.080 to 0.120 mm
Top ring spec. 0.00315 to 0.00472 in.
Second ring Allowable 0.15 mm
Clearance between limit 0.0059 in.
piston ring and
piston ring groove Factory 0.065 to 0.10 mm
spec. 0.0026 to 0.0039 in.
Oil ring
Allowable 0.15 mm
limit 0.0059 in.

W1148550
Connecting Rod Alignment
1. Remove the crankpin bearing, and install the connecting rod cap.
2. Install the piston pin in the connecting rod.
3. Install the connecting rod on the connecting rod alignment tool.
4. Put a gauge over the piston pin, and move it against the face
plate.
5. If the gauge does not fit squarely against the face plate, measure
the space between the pin of the gauge and the face plate.
6. If the measurement exceeds the allowable limit, replace the
connecting rod.
Space between gauge 0.05 mm
Allowable limit
pin face plate 0.0020 in.

W1031462

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(4) Crankshaft
Crankshaft Side Clearance
1. Set a dial indicator with its tip on the end of the crankshaft.
2. Measure the side clearance by moving the crankshaft to the front
and rear.
3. If the measurement exceeds the allowable limit, replace the
thrust bearings.
4. If the same size bearing is useless because of the crankshaft
journal wear, replace it with an oversize one referring to the table
and figure.
0.15 to 0.31 mm
Factory spec.
Crankshaft side 0.0059 to 0.0122 in.
clearance 0.50 mm
Allowable limit
0.0197 in.
(Reference)
• Oversize thrust bearing
Oversize Bearing Code Number Marking

0.2 mm Thrust bearing 1 02 15261-23950 020 OS

0.008 in. Thrust bearing 2 02 15261-23970 020 OS

0.4 mm Thrust bearing 1 04 15261-23960 040 OS

0.016 in. Thrust bearing 2 04 15261-23980 040 OS
• Oversize dimensions of crankshaft journal
0.2 mm 0.4 mm
Oversize
0.008 in. 0.016 in.
46.1 to 46.3 mm 46.3 to 46.5 mm
Dimension A
1.815 to 1.823 in. 1.823 to 1.831 in.
23.40 to 23.45 mm 23.80 to 23.85 mm
Dimension B
0.9134 to 0.9154 in. 0.9213 to 0.9232 in.
1.8 to 2.2 mm radius 1.8 to 2.2 mm radius
Dimension C
0.071 to 0.087 in. radius 0.071 to 0.087 in. radius
(0.8S)
The crankshaft journal must be fine-finished to higher than ∇∇∇∇.
*Holes to be de-burred and edges rounded with 1.0 to 1.5 mm
(0.0394 to 0.0591 in.) relief.
W1066738
Crankshaft Alignment
1. Support the crankshaft with V blocks on the surface plate at both
end journals.
2. Set a dial indicator with its tip on the intermediate journal.
3. Measure the crankshaft alignment.
4. If the measurement exceeds the allowable limit, replace the
crankshaft.
0.02 mm
Crankshaft alignment Allowable limit
0.0008 in.
W1067285

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Oil Clearance between Crankpin and Crankpin Bearing

1. Clean the crankpin and crankpin bearing.
2. Put a strip of plastigage on the center of the crankpin.
3. Install the connecting rod cap and tighten the connecting rod
screws to the specified torque, and remove the cap again.
4. Measure the amount of the flattening with the scale, and get the
oil clearance.
5. If the oil clearance exceeds the allowable limit, replace the
crankpin bearing.
6. If the same size bearing is useless because of the crankpin wear,
replace it with an undersize one referring to the table and figure.
■ NOTE
• Never insert the plastigage into the crankpin oil hole.
• Be sure not to move the crankshaft while the connecting rod
screws are tightened.
0.020 to 0.051mm
Oil clearance between Factory spec.
0.00079 to 0.00201 in.
crankpin and crankpin
bearing 0.15 mm
Allowable limit
0.0059 in.

33.959 to 33.975 mm
Crankpin O.D. Factory spec.
1.33697 to 1.33760 in.
33.995 to 34.010 mm
Crankpin bearing I.D. Factory spec.
1.33839 to 1.33898 in.
(Reference)
• Undersize crankpin bearing
Undersize Bearing Code Number Marking
0.2 mm
Crankpin bearing 02 15861-22970 020 US
0.008 in.
0.4 mm
Crankpin bearing 04 15861-20980 040 US
0.016 in.
• Undersize dimensions of crankpin
0.2 mm 0.4 mm
Undersize
0.008 in. 0.016 in.
2.3 to 2.7 mm radius 2.3 to 2.7 mm radius
Dimension A
0.091 to 0.106 in.radius 0.091 to 0.106 in.radius
1.0 to 1.5 mm relief 1.0 to 1.5 mm relief
*Dimension B
0.0394 to 0.0591 in. relief 0.0394 to 0.0591 in. relief
33.759 to 33.775 mm dia. 33.559 to 33.575 mm dia.
Dimension C
1.32910 to 1.32973 in. dia. 1.32122 to 1.32185 in. dia.
(0.8S)
The crankshaft journal must be fine-finished to higher than ∇∇∇∇.
*Holes to be de-burred and edges rounded with 1.0 to 1.5 mm
(0.0394 to 0.0591 in.) relief.
W11625390

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Oil Clearance between Crankshaft Journal and Crankshaft

Bearing 1
1. Measure the O.D. of the crankshaft front journal with an outside
micrometer.
2. Measure the I.D. of the crankshaft bearing 1 with an inside
micrometer, and calculate the oil clearance.
3. If the oil clearance exceeds the allowable limit, replace the
crankshaft bearing 1.
4. If the same size bearing is useless because of the crankshaft
journal wear, replace it with an undersize one referring to the
table and the figure.
0.034 to 0.106 mm
Oil Clearance between Factory spec.
0.00134 to 0.00417 in.
crankshaft journal and
crankshaft bearing 1 0.20 mm
Allowable limit
0.0079 in.

43.934 to 43.950 mm
Crankshaft journal O.D.
1.72968 to 1.73031 in.
Factory spec.
43.984 to 44.040 mm
Crankshaft bearing 1 I.D.
1.73165 to 1.73386 in.
(Reference)
• Undersize crankshaft bearing 1
Undersize Bearing Code Number Marking
0.2 mm
Crankshaft bearing 1 02 1G460-23910 020 US
0.008 in.
0.4 mm
Crankshaft bearing 1 04 1G460-23920 040 US
0.016 in.
• Undersize dimensions of crankshaft journal
0.2 mm 0.4 mm
Undersize
0.008 in. 0.016 in.
1.8 to 2.2 mm radius 1.8 to 2.2 mm radius
Dimension A
0.071 to 0.087 in.radius 0.071 to 0.087 in.radius
1.0 to 1.5 mm relief 1.0 to 1.5 mm relief
*Dimension B
0.0394 to 0.0591 in. relief 0.0394 to 0.0591 in. relief
43.734 to 43.750 mm dia. 43.534 to 43.550 mm dia.
Dimension C
1.72181 to 1.72244 in. dia. 1.71394 to 1.71457 in. dia.
(0.8S)
The crankshaft journal must be fine-finished to higher than ∇∇∇∇.
*Holes to be de-burred and edges rounded with 1.0 to 1.5 mm
(0.0394 to 0.0591 in.) relief.
W10323470
Replacing Crankshaft Bearing 1
(When removing)
1. Press out the used crankshaft bearing 1 using a crankshaft
bearing 1 replacing tool.
(When installing)
1. Clean a new crankshaft bearing 1 and crankshaft journal bore,
and apply engine oil to them.
2. Using a crankshaft bearing 1 replacing tool, press in a new
bearing 1 (2) so that its seam (1) directs toward the exhaust
manifold side. (See figure.)
0.0 to 0.3 mm
Dimension (A) Factory spec.
0.0 to 0.0118 in.

(1) Seam (A) Dimension

(2) Crankshaft Bearing 1 (a) 0.366 rad (21 °)
(3) Cylinder Block
W10342000

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Oil Clearance between Crankshaft Journal and Crankshaft

Bearing 2 (Crankshaft Bearing 3)
1. Put a strip of plastigage on the center of the journal.
2. Install the bearing case and tighten the bearing case screws 1 to
the specified torque, and remove the bearing case again.
3. Measure the amount of the flattening with the scale, and get the
oil clearance.
4. If the oil clearance exceeds the allowable limit, replace the
crankshaft bearing 2 (crankshaft bearing 3).
5. If the same size bearing is useless because of the crankshaft
journal wear, replace it with an undersize one referring to the
table and figure.
■ NOTE
• Be sure not to move the crankshaft while the bearing case
screws are tightened.
Oil clearance between 0.028 to 0.059 mm
Factory spec.
crankshaft journal and 0.00110 to 0.00232 in.
crankshaft bearing 2 0.20 mm
(crankshaft bearing 3) Allowable limit
0.0079 in.

Crankshaft journal O.D. 43.934 to 43.950 mm

Factory spec.
(Flywheel side) 1.72968 to 1.73031 in.
Crankshaft bearing 2 43.978 to 43.993 mm
Factory spec.
I.D. 1.73142 to 1.73201 in.

Crankshaft journal O.D. 43.934 to 43.950 mm

Factory spec.
(Intermediate) 1.72968 to 1.73031 in.
43.978 to 43.993 mm
Crankshaft bearing 3 I.D. Factory spec.
1.73142 to 1.73201 in.
W10344030

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Oil Clearance between Crankshaft Journal and Crankshaft

Bearing 2 and Crankshaft Bearing 3 (Continued)
(Reference)
• Undersize crankshaft bearing 2 and 3
Oversize Bearing Code Number Marking
Crankshaft bearing 2 02 15694-23930
020 US
0.2 mm Crankshaft bearing 2F 02 1G460-07530
0.008 in. Crankshaft bearing 3 02 1G460-07580
020 US
Crankshaft bearing 3F 02 1G460-07630
Crankshaft bearing 2 04 15694-23940
040 US
0.4 mm Crankshaft bearing 2F 04 1G460-07540
0.016 in. Crankshaft bearing 3 04 1G460-07590
040 US
Crankshaft bearing 3F 04 1G460-07640

• Undersize dimensions of crankshaft journal

0.2 mm 0.4 mm
Undersize
0.008 in. 0.016 in.
1.8 to 2.2 mm radius 1.8 to 2.2 mm radius
Dimension A
0.071 to 0.087 in.radius 0.071 to 0.087 in.radius
1.0 to 1.5 mm relief 1.0 to 1.5 mm relief
*Dimension B
0.0394 to 0.0591 in. relief 0.0394 to 0.0591 in. relief
43.734 to 43.750 mm dia. 43.534 to 43.550 mm dia.
Dimension C 1.72181 to 1.71394 to
1.72244 in. dia. 1.7147 in. dia.
(0.8S)
The crankshaft journal must be fine-finished to higher than ∇∇∇∇.
*Holes to be de-burred and edges rounded with 1.0 to 1.5 mm
(0.0394 to 0.0591 in.) relief.

W1047088

(5) Cylinder
Cylinder Wear
1. Measure the I.D. of the cylinder at the six positions (see figure)
with a cylinder gauge to find the maximum and minimum I.D.’s.
2. Get the difference (Maximum wear) between the maximum and
the minimum I.D.’s.
74.500 to 74.519 mm
Factory spec.
2.93307 to 2.93382 in.
Cylinder I.D.
74.669 mm
Allowable limit
2.93972 in.

(A) Top (a) Right-Angled to Piston Pin

(B) Middle (b) Piston Pin Direction
(C) Bottom (Skirt)
W1070089

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Correcting Cylinder (Oversize)

1. When the cylinder is worn beyond the allowable limit, bore and
hone it to the specified dimension.
75.000 to 75.019 mm
Factory spec.
2.95276 to 2.95350 in.
Cylinder liner I.D.
75.150 mm
Allowable limit
2.95866 in.
Hone to 2.2 to 3.0 µmRz
Finishing (0.000087 to 0.00012 in.Rz)
∇∇∇.

2. Replace the piston and piston rings with oversize ones.

Oversize : 0.5 mm (0.01969 in.)
Marking : 05
■ NOTE
• When the oversize cylinder is worn beyond the allowable
limit, replace the cylinder block with a new one.
(1) Cylinder I.D. (Before Correction) (2) Cylinder I.D. [Oversize]
W10367470

(6) Oil Pump

Rotor Lobe Clearance
1. Measure the clearance between lobes of the inner rotor and the
outer rotor with a thickness gauge.
2. If the clearance exceeds the factory specifications, replace the oil
pump rotor assembly.
0.03 to 0.14 mm
Rotor lobe clearance Factory spec.
0.0012 to 0.0055 in.
W10378950

Clearance between Outer Rotor and Pump Body

1. Measure the clearance between the outer rotor and the pump
body with a thickness gauge.
2. If the clearance exceeds the factory specifications, replace the oil
pump rotor assembly.
Clearance between
0.07 to 0.15 mm
outer rotor and pump Factory spec.
0.0028 to 0.0059 in.
body
W10381420

Clearance between Rotor and Cover

1. Put a strip of plastigage onto the rotor face with grease.
2. Install the cover and tighten the screws.
3. Remove the cover carefully, and measure the amount of the
flattening with the scale and get the clearance.
4. If the clearance exceeds the factory specifications, replace oil
pump rotor assembly.
Clearance between rotor 0.075 to 0.135 mm
Factory spec.
and cover 0.00295 to 0.00531 in.

W10382660

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WG972-E2, DF972-E2, WSM GASOLINE / LPG ENGINE

(7) Starter
Overrunning Clutch
1. Inspect the pinion for wear or damage.
2. If there is any defect, replace the overrunning clutch assembly.
3. Check that the pinion turns freely and smoothly in the
overrunning direction and does not slip in the cranking direction.
4. If the pinion slips or does not rotate in the both directions, replace
the overrunning clutch assembly.
W1075769

Commutator and Mica

1. Check the contact face of the commutator for wear, and grind the
commutator with emery paper if it is slightly worn.
2. Measure the commutator O.D. with an outside micrometer at
several points.
3. If the minimum O.D. is less than the allowable limit, replace the
armature.
4. If the difference of the O.D.’s exceeds the allowable limit, correct
the commutator on a lathe to the factory specification.
5. Measure the mica undercut.
6. If the undercut is less than the allowable limit, correct if with a saw
blade and chamfer the segment edges.
28.0 mm
Factory spec.
1.102 in.
Commutator O.D.
27.0 mm
Allowable limit
1.063 in.

Less than 0.05 mm

Factory spec.
0.0020 in.
Difference of O.D.'s
0.40 mm
Allowable limit
0.0157 in.

0.50 to 0.80 mm
Factory spec.
0.0197 to 0.0315 in.
Mica under cut
0.20 mm
Allowable limit
0.0079 in.

(1) Segment (a) Good

(2) Undercut (b) Bad
(3) Mica
W1075277

Brush Wear
1. If the contact face of the brush is dirty or dusty, clean it with emery
paper.
2. Measure the brush length (A) with vernier calipers.
3. If the length is less than the allowable limit, replace the yoke
assembly and brush holder.
16.0 mm
Factory spec.
0.630 in.
Brush length (A)
10.5 mm
Allowable limit
0.413 in.

(A) Brush Length

W1075476
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WG972-E2, DF972-E2, WSM GASOLINE / LPG ENGINE

Brush Holder
1. Check the continuity across the brush holder and the holder
support with an ohmmeter.
2. If it conducts, replace the brush holder.
W1076066

Armature Coil
1. Check the continuity across the commutator and armature coil
core with an ohmmeter.
2. If it conducts, replace the armature.
3. Check the continuity across the segments of the commutator with
an ohmmeter.
4. If it does not conduct, replace the armature.
W1075693

Field Coil
1. Check the continuity across the lead (1) and brush (2) with an
ohmmeter.
2. If it does not conduct, replace the yoke assembly.
3. Check the continuity across the brush (2) and yoke (3) with an
ohmmeter.
4. If it conducts, replace the yoke assembly.

(1) Lead (3) Yoke

(2) Brush
W1076156

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 EDITOR:
KUBOTA FARM & INDUSTRIAL MACHINERY SERVICE, LTD.
64, ISHIZU-KITAMACHI, SAKAI-CITY, OSAKA, 590-0823, JAPAN
PHONE : (81)72-241-1129
FAX : (81)72-245-2484
E-mail : ksos-pub@kubota.co.jp

Printed in Japan 2006. 01, S, EI, E I, e Code No.97897-02672

KUBOTA Corporation 2003. 12, S, EI, E I, e