4
ADJUSTMENTS
62
GB
ADJUSTING THE IDLE SPEED
Idling adjustment greatly affects the ap-
propriate start-up and the accelerator
response.
Idling is adjusted through adjustment screw
1 and air adjustment screw 2. Adjustment
screw 1 adjusts the basis position of the
gas valve. Turn the screw clockwise to
increase the rotation conditions and coun-
terclockwise to diminish it. The air adjust-
ment screw 2 adjusts the quantity of which
is mixed to the fuel for idling. If the screw is
turned clockwise, the quantity of air dimin-
ishes (thin mix), if turned counterclockwise,
the quantity of air increases (fat mix).
To properly adjust the idle speed, follow these steps:
• Tighten the air adjustment screw no. 2 fully and then loosen it up to the value described
in the carburetor setting table (page. 23).
• Warm the engine for approx. 5 minutes, until the operational temperature is attained.
• Slowly turn the air adjustment screw clockwise, until idling starts diminishing.
• Mark the position, then slowly turn the air adjustment screw no. 2 counterclockwise, until
idling decreases again.
• Adjust the screw between these two positions, at the highest idling point.
If a remarkable increase in the rpm occurred during the adjustment above, idling is to be
reduced and taken back to the normal level, and then execute the above procedure.
If no satisfactory results are obtained after the procedure, this may be due to an incorrect
slow-running jet.
If the air adjustment screw has been thoroughly tightened, but the rpm have not varied, a
lower size slow-running jet is to be used.
Execute the adjustment procedure again after replacing the jet.
NOTE:
The correct idling should be between 1500 and 1600 rpm.
1
2
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