SERVICE INFORMATION
9
CS-3700ES
CS-4200ES
H
L
A
B
B
A
H mixture needle
L mixture needle
Idle adjust screw
C
2-3 Adjusting carburetor
1. Start engine and warm it up at idle for one minute.
Turn H mixture needle anticlockwise until engine
speed drops to approx. 11,000 r/min.
2. Warm it up well for 100 sec with cycle of 5
seconds at WOT (Wide Open Throttle) and 5
seconds at idling.
NOTE : Do not run engine at high speed without
load longer than 5 seconds, or engine damage may
occur.
3. Adjust L mixture needle with 2.5 mm blade
screwdriver to reach maximum engine speed just
before lean drop off.
4. Set idle engine speed to 3,700 r/min by turning idle adjust screw. Engine speed should be stable at
3,700 +/- 10 r/min after idle adjust screw adjustment.
5. Turn L mixture needle anticlockwise reducing engine idle speed 1,000 r/min to set idle speed at 2,700
r/min. The engine idle speed range is 2,500 - 2,900 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.
6. Make sure WOT engine speed is approx. 11,000 r/min. If WOT engine speed is over 11,500 r/min, turn
H mixture needle anticlockwise until engine speed drops to approx. 11,000 r/min. Turn H mixture needle
1/8 turn increments clockwise at idle engine speed, then squeeze throttle trigger and check WOT engine
speed. If the WOT engine speed is less than 11,500 r/min, turn H mixture needle 1/8 turn clockwise again,
and check WOT engine speed. The final WOT engine speed should fall within the11,600 to 12,400 r/min
range.
7. After adjusting carburettor, screw new limiter cap
on the limiter cap removal tool 91019 (C)
anticlockwise approx. 2 turns as shown, and put the
limiter caps on L and H mixture needles respectively
and remove the limiter cap tool. And then press the
caps on L and H mixture needles with bar tool.
NOTE : Align the limiter cap’s tabs (A) with locating
slots (B) in extended housing of carburettor.
IMPORTANT : The limiter caps must be installed L and H mixture needles to comply with Emission
Directive.
8. Start engine, and verify engine idle speed ranges from 2,300 to 3,000 r/min, and WOT engine speed
ranges from 11,500 to 12,500 r/min. Make sure chain does not rotate when engine is idling. When final
adjustment is completed, the engine should idle, accelerate smoothly, and attain WOT per above
specification.
NOTE : Initial carburettor setting (idle adjust screw, L and H mixture needles) shown on page 3 and 8 is
to start the engine after restoration or carburettor change. Idle adjust screw, idle and H needles turn for
designated engine revolution through procedures indicated here may vary. As long as idle and WOT engine
speed is set in given range, variance would be ignorable.
