Adjusting Carburettor - Echo CS-3700ES Service Data

CS-3700ES
CS-4200ES
2-3 Adjusting carburetor
Idle adjust screw
L mixture needle
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.
C
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.
SERVICE INFORMATION
H mixture needle
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.
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.
B
L
A
9
H
A
B