01-67G-00 CS-680 1

SERVICE DATA
CHAIN SAW
CS-680
(Serial number : 36000001 and after)

INTRODUCTION CONTENTS
page
We are constantly working on technical im- 1 SERVICE INFORMATION .............................. 2
provement of our products. For this reason, 1-1 Specification ............................................... 2
technical data, equipment and design are 1-2 Technical data ............................................. 3
subject to change without notice. All speci- 1-3 Torque limits................................................ 4
fications and directions in this SERVICE 1-4 Special repairing materials ......................... 5
DATA are based on the latest product infor- 1-5 Service limits............................................... 6
1-6 Special tools ............................................... 7
mation available at the time of publication.
ECHO SERVICE MANUAL Ord. 401-23
2 CARBURETTOR ADJUSTMENT PROCEDURE .. 8
(Model : CS-6702) contains lots of informa- 2-1 General adjusting rules ............................... 8
tion for servicing this model. 2-2 Presetting Idle adjust screw, L mixture needle
and H mixture needle ....................................... 8
2-3 Adjusting carburettor................................. 10

Reference No. 01-67G-00

ISSUED: 200901
2 SERVICE INFORMATION CS-680

1 SERVICE INFORMATION

1-1 Specifications
Dimensions Length mm(in) 435 (17.13)
Width mm(in) 236 (9.29)
Height mm(in) 302 (11.89)
Dry weight* kg(lb) 6.6 (14.5)
Engine Type KIORITZ, air-cooled, two-stroke, single cylinder
Ventilated piston, Semi-automatic decompression
Rotation Clockwise as viewed from the output end
Displacement cm3(in3) 66.8 (4.076)
Bore mm(in) 50.0 (1.969)
Stroke mm(in) 34.0 (1.339)
Compression ratio 7.6
Carburettor Type Diaphragm horizontal-draught
Model Walbro HDA-272
Venturi size-Throttle bore mm(in) 15.08 - 19.03 (0.594 - 0.749)
Ignition Type CDI (Capacitor discharge ignition) system
with electronic timing advancer
Spark plug BPMR7A
Starter Type Automatic rewind
Rope diameter x length mm(in) 4.5 x 950 (0.18 x 37.4)
Fuel Type Premixed two-stroke fuel
Mixture ratio 50 : 1 (2 %)
Petrol Minimum 89 octane petrol
Two-stroke air cooled engine oil ISO-L-EGD (ISO/CD13738), JASO FC/FD
Tank capacity L (U.S.fl.oz.) 0.64 (21.6)
Clutch Type Centrifugal, 3-shoe slide with 3-tension spring
Guide bar / Saw chain lubrication type Automatic with volume adjuster and manual override
Tank capacity, oil L (U.S.fl.oz.) 0.37 (12.5)
Sprocket Type Floating rim
Number of teeth 7
Pitch in 3/8
Guide bar Type 45S58 50S58 60S58
45RS58-3/8E 50RS58-3/8E 60RS58-3/8E
Called length cm 45 50 60
Gauge in 0.058
Saw chain Type CARLTON A2LM OREGON 73LGX
Number of drive links 64 72 84
Pitch in 3/8
Gauge in 0.058
* Without guide bar and saw chain.
CS-680 SERVICE INFORMATION 3
1-2 Technical data
Engine
Idling speed r/min 2,600 +/- 300
Operating speed r/min 9,500 - 10,000
Wide open throttle speed* r/min 12,900 - 13,900
Clutch engagement speed r/min 3,600 - 4,300
Compression pressure MPa (kgf/cm2) (psi) 0.87 (8.9) (126)
Ignition system
Spark plug gap mm(in) 0.6 - 0.7 (0.024 - 0.028)
Minimum secondary voltage at 1,200 r/min kV 21
Secondary coil resistance kΩ 1.7 - 2.2
Pole shoe air gaps mm(in) 0.30 - 0.40 (0.012 - 0.016)
Ignition timing at 1,500 r/min °BTDC 8
at 3,000 r/min °BTDC 15
at 8,000 r/min °BTDC 24
at 10,000 r/min °BTDC 25
Carburettor
Idle adjust screw initial setting turn in** 1/2
L mixture needle initial setting turns back*** 2 1/4
H mixture needle initial setting turns back*** 1 1/8
Test Pressure, minimum MPa (kgf/cm2) (psi) 0.05 (0.5) (7.0)
Metering lever height mm(in) Flush with diaphragm seat
Chain oil discharge volume at 7,000 r/min Adjustable 3 - 13 (0.09 - 0.39)
mL/min(U.S.fl.oz./min) (Factory set 7.5 mL/min)

BTDC: Before top dead centre.

*With 50 cm guide bar and properly adjusted saw chain.
**Set idle adjust screw to the point that its tip just contacts throttle plate before initial setting.
***Turn L/H mixture needles anticlockwise from point that needle is lightly seated.
4 SERVICE INFORMATION CS-680

1-3 Torque limits

Descriptions Size kgf•cm N•m in•lbf
Starter Starter pawl M5 70 - 110 7 - 11 60 - 95
system
Starter centre shaft screw M 5* 70 - 110 7 - 11 60 - 95
Starter case M5 20 - 35 2 - 3.5 17 - 30
Ignition Magneto rotor (Flywheel) M8 230 - 270 23 - 27 200 - 235
system
Ignition coil M4 35 - 50 3.5 - 5 30 - 45
Spark plug M 14 130 - 170 13 - 17 113 - 150
Fuel Carburettor M5 20 - 40 2 - 4 17 - 35
system
Carburettor case M5 50 - 70 5 - 7 45 - 60
Intake bellows M5 70 - 110 7 - 11 60 - 95
Clutch Clutch hub LM 10 450 - 550 45 - 55 390 - 480
Engine Crankcase M 5† 70 - 110 7 - 11 60 - 95
†
Cylinder M5 70 - 110 7 - 11 60 - 95
Cylinder cover M5 30 - 50 3 - 5 25 - 35
Muffler M 5* 70 - 110 7 - 11 60 - 95
Muffler bracket M5 35 - 50 3.5 - 5 30 - 45
Muffler lid M4 35 - 50 3.5 - 5 30 - 45
Others Auto-oiler M4 35 - 50 3.5 - 5 30 - 45
Cushion Front handle M5 70 - 110 7 - 11 60 - 95
Crankcase M5 35 - 50 3.5 - 5 30 - 45
Cushion bracket M5 70 - 110 7 - 11 60 - 95
Compression Cushion bracket M5 50 - 70 5 - 7 45 - 60
spring Crankcase M 5* 35 - 50 3.5 - 5 30 - 45
Eye plate Compression M 4* 35 - 50 3.5 - 5 30 - 45
spring M 5* 35 - 50 3.5 - 5 30 - 45
Front handle M 5* 70 - 110 7 - 11 60 - 95
Brake lever (Hand guard) M5 25 - 45 2.5 - 4.5 22 - 40
Brake cover nut M 3* 6 - 10 0.6 - 1 5 - 9
Ignition switch M 10 10 - 30 1 - 3 9 - 25
Guide bar M8 200 - 230 20 - 23 175 - 200
Regular bolt, nut and screw M3 6 - 10 0.6 - 1 5 - 9
M4 15 - 25 1.5 - 2.5 13 - 22
M5 25 - 45 2.5 - 4.5 22 - 40
M6 45 - 75 4.5 - 7.5 40 - 65
M8 110 - 150 11 - 15 95 - 130
LM: Left-hand thread
*Thread locking sealant (See next page)
†
The torque difference between four bolts should not exceed 20 kgf•cm (2N•m, 17in•lbf) per bolt.
CS-680 SERVICE INFORMATION 5
1-4 Special repairing materials
Material Location Remarks
Adhesive Guide bar stud Loctite #609, ThreeBond 1373 or equivalent
Starter centre shaft screw
Loctite #222, ThreeBond1342 or equivalent
Brake cover nut
Grease Auto-oiler worm
Clutch needle bearing
Rubber cushion, inside
Choke knob Lithium based grease or ECHO XTended
Rewind spring Protection TM Lubricant
Oil seal inner lips
Starter centre shaft
Chain brake (metal contact part) Molybdenum grease (approx. 1 gram)
Thread locking sealant Front handle
Compression spring Crankcase
Loctite #242, ThreeBond #1324 or equivalent
Eye plate
Muffler
6 SERVICE INFORMATION CS-680

1-5 Service Limits

A B C D

5K253 5K083 5K084 5K081

E F G H

5K082 5K016 5K025 5K254

K L M P

2
5K173 5K174 5K181 5K097
3

4
5
6

Description 0 7
mm (in)
5 8

A Cylinder bore When plating is worn and aluminium can be seen 10 9

10

B Piston outer diameter Min. 49. 83 (1.962)

11

C Piston pin bore Max. 12. 035 (0.4738)

D Piston ring groove Max. 1. 3 (0.051)
E Piston ring side clearance Max. 0. 1 (0.004)
F Piston pin outer diameter Min. 11. 98 (0.4717)
G Piston ring width Min. 1. 15 (0.045)
H Piston ring end gap Max. 0. 5 (0.02)
K Con-rod small end bore Max. 16. 025 (0.6309)
L Crankshaft runout Max. 0. 01 (0.001)
M Sprocket bore Max. 14. 07 (0.5539)
N Clutch drum bore Max. 79. 0 (3.11)
P Sprocket wear limit Max. 0. 5 (0.02)
CS-680 SERVICE INFORMATION 7
1-6 Special tools
1 2 a = 3 mm 4 5 b = 4 mm 7 8
3 a = 4 mm 6 b = 5 mm
b

9 10 11 12 13

14 15 16 17 19 20

18

21 22 23 24
50

0.4
0

0.8
0
9

1.2
01
e
00 m ug
91

MPa
91 5m a

1.
3 G
P = ap
4 G
01 ir

4
#. A

/N .
n
tio
ni
Ig

Key Part Number Description Used for:

1 897801-33330 Tachometer PET-1000 Measuring engine speed to adjust carburettor
2 895612-79920 L-hex wrench (3 mm) Removing and installing hex. socket bolt (M4)
3 895610-79920 L-hex wrench (4 mm) Removing and installing hex. socket bolt (M5)
4 897537-30130 Piston stopper Locking crankshaft rotation
5 897724-01361 Spring pin tool (4 mm) Removing and installing spring pin (4 mm dia)
6 897724-02831 Spring pin tool (5 mm) Removing and installing spring pin (5 mm dia)
7 897719-02830 Piston holder Making piston steady to remove and install piston / rings
8 897702-30131 Piston pin tool Removing and installing piston pin
9 897501-03938 Puller Removing magneto rotor
10 897500-00335 Puller Removing auto oiler oil cover
11 897502-19830 Crankcase tool Separating crankcase
12 897701-14732 Bearing tool Removing and installing ball bearings on crankcase
13 897708-19835 Worm puller Removing auto-oiler worm
14 Y089-000040 Worm inserter Installing auto-oiler worm
15 897727-19830 Oil seal tool Installing clutch side oil seal
16 897726-21430 Oil seal tool Installing starter side oil seal
17 897826-16131 Pressure rubber plug Plugging intake port to test crankcase / cylinder leakages
18 897827-16131 Pressure plate Plugging intake port to test crankcase / cylinder leakages
19 897800-79931 Spark tester Checking ignition system
20 897803-30133 Pressure tester Testing carburettor leakages
21 91024 Pressure tester Testing crankcase leakages
22 91019 Limiter cap tool Removing and installing limiter cap
23 91004 Module air gap gauge Adjusting pole shoe air gaps
24 91037 Compression gauge Measuring cylinder compression
8 SERVICE INFORMATION CS-680

2 CARBURETTOR ADJUSTMENT PROCEDURE

2-1 General adjusting rules

A. Before adjustment, check the following items.

1. The correct spark plug must be clean and properly gapped.

2. The air filter element must be clean and properly installed.

3. The muffler exhaust port must be clear of carbon.

4. The fuel lines, tank vent and fuel filter are in good condition and clear of debris.

5. The fuel is fresh ( > 89 octane : RON ) and properly mixed at 50 : 1 with “ISO L-EGD” or “JASO FC/
FD” 2-stroke oil.

6. The recommended bar and chain must be installed, and properly tensioned.

NOTE : In order to achieve proper carburettor adjustment, a 50 cm bar and chain should be installed on
the unit. Otherwise serious engine damage will occur due to overspeeding.

B. Adjustment with limiter caps on carburettor.

Set L and H mixture needles fully anticlockwise. Start and run engine for two minutes alternating engine
speed between WOT for 5 seconds and idle for 5 seconds. Adjust idle speed screw to 2,600 +/- 150
r/min. Adjust H mixture needle with limiter cap to 13,400 +/- 300 r/min. If engine does not run correctly af-
ter this adjustment, proceed to the next step 2-2.

IMPORTANT : After adjusting carburettor according to the steps 2-2 and 2-3, the limiter cap(s)
must be installed on L and H mixture needle(s) to comply with Emission Directive.

2-2 Presetting Idle adjust screw, L mixture needle and H mixture needle
Tools Required : Small screwdriver with 2.5 mm
blade, electronic tachometer P/N 897801-33330,
limiter cap removal tool with 2.5 mm left-hand
thread P/N 91019. Parts Required : (2) limiter caps
P/N P003-000010.

1. Turn the L and H mixture needles anticlockwise

to rich side stop to align limiter cap tab (A) with lo-
cating slot (B), using 2.5 mm blade screwdriver.

A B NOTE : If cap tabs (A) misalign with locating slots

(B), the cap cannot be removed and the centre
hole threads will strip. If centre hole threads strip,
use 3 mm diameter thread wood screw to remove
the limiter cap.

A B

(continued)
CS-680 SERVICE INFORMATION 9
2-2 Presetting Idle adjust screw, L mixture needle and H mixture needle (continued)

2. Screw 2.5 mm limiter cap removal tool P/N

91019 anticlockwise into centre hole of either lim-
iter cap until tab of the limiter cap just comes out of
the locating slot.

NOTE : DO NOT COMPLETELY REMOVE LIM-

ITER CAP FROM Carburettor!

If the first limiter cap is removed completely, the

second limiter cap can be misaligned while insert-
ing the cap removal tool.

3. Remove the limiter cap removal tool from the

limiter cap by turning the tool clockwise, leaving
the limiter cap in place.

4. Screw 2.5 mm limiter cap removal tool P/N

91019 anticlockwise into centre hole of remaining
limiter cap until the limiter cap is removed from the
mixture needle completely. Remove the limiter cap
from limiter cap removal tool by turning clockwise,
then screw limiter cap removal tool into centre hole
of previous limiter cap to remove completely.

5. Turn L and H mixture needle clockwise until

lightly seated, then turn both mixture needles anti-
clockwise for initial setting as follows :

L mixture needle : 2 1/4, H mixture needle : 1 1/8

NOTE : If needles are forced during seating, dam-

age to carburettor may occur.

6. Remove air cleaner lid and air filter to expose

the Idle adjust screw and throttle plate. Turn Idle
adjust screw anticlockwise and set the screw until
the tip just contacts the throttle plate. Then turn
Idle adjust screw 1/2 turns clockwise. Reinstall air
filter, and cleaner lid.

NOTE : The initial carburettor settings for Idle ad-

just screw, Idle and Hi speed mixture needles are
intended to start and run the engine before final
carburettor adjustments are made through this
procedure. The actual number of turns needed for
engine operation may vary.
10 SERVICE INFORMATION CS-680

2-3 Adjusting carburettor

1. Start and warm engine for 1 minute alternat-
Idle adjust screw ing engine speed between WOT and idle every 5
seconds. Turn H mixture needle anticlockwise until
engine speed drops to approx. 11,500 r/min at WOT.
NOTE : Do not run engine at high speed without
load longer than 10 seconds, or engine damage
may occur.
2. Adjust L mixture needle using 2.5mm blade
screwdriver to reach maximum engine r/min just
before lean r/min drop off.
3. Set idle speed to 3,600 r/min by turning Idle
adjust screw. Engine speed should be stable
H mixture needle L mixture needle at 3,600 +/- 50 r/min after idle adjust screw
adjustment.
4. Turn L mixture needle anticlockwise reducing engine idle speed 1,000 r/min to set idle speed at 2,600
r/min. The idle speed range is 2,500 - 2,700 r/min.
NOTE : Engine speed must be allowed to stabilize a minimum of 20 seconds after each adjustment of L
mixture needle to assure accurate tachometer readings.
5. Before adjustment, WOT engine speed should be 11,500 r/min or less. If r/min is higher, turn H mixture
needle anticlockwise until 11,500 r/min is achieved. To make the final WOT engine speed adjustment, turn
the H mixture needle clockwise in 1/8 turn increments with the engine at idle. After each adjustment, ac-
celerate to WOT, and check r/min. The final r/min should fall within 13,000 - 13,800 r/min.
NOTE : When the H mixture needle is turned completely clockwise, the engine will continue to run. If the
engine speed at WOT is above 14,300 r/min, adjust H mixture needle anticlockwise and set maximum
engine speed at less than 13,900 r/min.
6. After adjusting carburettor, put new limiter cap
on the other side (c) of limiter cap tool (C) as
shown. Align the limiter cap’s tabs (A) with locating
slots (B) in extended housing of carburettor and
press the limiter caps to the bottoms on L and H
mixture needles respectively.

A B
c

A B

IMPORTANT : The limiter caps must be properly installed on L and H mixture needles to comply
with Emission Directive.
7. Start engine, and verify engine idle speed ranges from 2,300 to 2,900 r/min, and WOT engine speed
ranges from 12,900 to 13,900 r/min. Make sure the chain does not rotate when engine is idling. When
final adjustment is completed, the engine should idle, accelerate smoothly, and attain WOT per above
specifications.