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SERVICE INFORMATION

PB-655
PB-755

8

2-3 Adjusting carburettor

1. Start engine and warm it up alternating engine
speed between WOT and idle every 10 seconds for
1 minute.

2. Adjust  idle mixture needle with 2.5 mm blade
screwdriver (E) to reach maximum engine speed
just before drop off.

3. Set idle speed to 2,800 r/min by turning idle adjust
screw. Engine speed ranges 2,800 +/- 30 r/min after
idle adjust screw adjustment.

4. Turn idle mixture needle anticlockwise to reduce
idle speed 200 to 300 r/min in the range of 2,500 to
2,600 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. Adjust hi speed (H) mixture needle and obtain
maximum WOT engine speed just before lean drop
off using 2.5mm blade screwdriver.

6. Turn hi speed (H) mixture needle anticlockwise
to reduce WOT engine speed 10-20 r/min. Minimum
WOT engine speed after adjusting should be over
6,800 r/min.

7. Start engine, and verify engine idle speed ranges
from 2,400 to 2,800 r/min, and WOT engine speed
ranges from 6,800 to 7,300 r/min. When final
adjustment is completed, the engine should idle,
accelerate smoothly, and attain WOT per above
specification.

8. After adjusting carburettor, insert and secure new
plug(s)  (F) A259-000000 deep in the needle holes
per the Emission Directive using limiter plug tool (C).

NOTE : 

Engine WOT, and idle speed r/min in field

o p e r a t i o n   m a y   v a r y   f r o m   f i n a l   a d j u s t m e n t
specifications due to changing ambient conditions,
fuel, and engine loads. Safe engine rpm variances
should be within the WOT, Idle speed ranges listed
in Section 1-1, otherwise the carburetor should be
readjusted.

(E)

(F)

(C)

Summary of Contents for PB-655

Page 1: ...f publication ECHO SERVICE MANUAL Ord No 403 12 contains lots of information for servicing these models 2 CONTENTS page 1 SERVICE INFORMATION 2 1 1 Specification 2 1 2 Technical data 3 1 3 Torque limi...

Page 2: ...gnition Type CDI Capacitor discharge ignition system Spark plug BPM8Y Exhaust Muffler type Spark arrestor muffler Starter Type Automatic rewind Rope diameter x length mm in 3 5 x 1000 9 64 x 39 1 2 Fu...

Page 3: ...e shoe air gaps mm in 0 3 0 4 0 012 0 016 Ignition timing BTDC 30 Carburettor Venturi size mm in 15 0 0 591 Throttle bore mm in 15 0 0 591 Idle adjust screw initial setting turn back 8 Idle mixture ne...

Page 4: ...15 17 130 150 system Carburettor M 5 40 55 4 5 5 35 48 Intake insulator M 5 35 45 3 5 4 5 30 40 Fuel tank M 5 20 40 2 4 17 35 Engine Crankcase M 5 70 110 7 11 60 95 Cylinder M 5 70 110 7 11 60 95 Engi...

Page 5: ...D Piston ring groove 1st Max 1 65 0 065 2nd Max 1 6 0 063 E Piston ring side clearance Max 0 1 0 004 F Piston pin outer diameter Min 9 98 0 393 G Piston ring width Min 1 45 0 057 H Piston ring end ga...

Page 6: ...0 2 pin wrench Removing and installing pawl carrier 13 897719 02830 Piston holder Making piston steady to remove and install piston rings 14 897726 21430 Oil seal tool Installing crankcase oil seal 15...

Page 7: ...carburettor change Idle adjust screw idle and H mixture needles turn for designated engine revolution through procedures indicated here may vary As long as idle and WOT engine speed is set in given r...

Page 8: ...um WOT engine speed just before lean drop off using 2 5mm blade screwdriver 6 Turn hi speed H mixture needle anticlockwise to reduce WOT engine speed 10 20 r min Minimum WOT engine speed after adjusti...

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