SERVICE A ADJUSTMENTS

TO ADJUST CARBURETOR (See Fig. 28)

The carburetor has been preset at the factory and adjust- ment should not be necessary,. However, minor adjust- ment may be required to compensate for differences in fuel, temperature, altitude or load.. If the carburetor does need adjustment, proceed as follows:

in general, turning idle mixture valve in (clockwise) de- creases the supply of fuel to the engine giving a leaner fuel/ air mixture. Turning the idle mixture valve out (counter_

clockwise) increases the supply of fuel to the engine giving a richer fuel/air mixture,.

IMPORTANT: DAMAGE TO THE NEEDLE VALVE AND THE SEAT IN CARBURETOR MAY RESULT IF SCREW IS TURNED IN TOO TIGHT,

PRELIMINARY SETTING -

=Air cleaner assembly must be assembled to the carbu- retor when making carburetor adjustments.

=Be sure the throttle control cable is adjusted properly (see above)..

With engine off turn idle mixture valve in (clockwise) closing it finger tight and then turn out (counterclock- wise) 1 full turn..

FINAL SETTING -

Start engine and allow to warm for five minutes. Make final adjustments with engine running and shift/motion control lever in neutral (N) position_

-Move throttle control lever to slow (,_) position. With finger, rotate and hold throttle lever against idle speed screw. Turn idle speed screw to attain 1750 RPM.

oWhile still holding throttle lever against idle speed screw, turn idte mixture valve in (clockwise) until en- gine begins to die and then turn out (counterclockwise) until engine runs rough,. Turn valve to a point midway between those two positionso Release throttle lever..

ACCELERATION TEST -

°Move throttle control lever from slow (,_) to fast (,@) positiono if engine hesitates or dies, turn idle mixture

valve out (counterclockwise) 1/8 turn. Repeat test and continue to adjust, if necessary, until engine acceler- ates smoothly,.

High speed stop is factory adjusted. Do not adjust - damage may result°

IMPORTANT: NEVER TAMPER WiTH THE ENGINE

GOVERNOR, WHICH IS FACTORY SET FOR PROPER

ENGINE SPEED. OVERSPEEDINGTHE ENGINE ABOVE

THE FACTORY HIGH SPEED SETTING CAN BE

DANGEROUS. IF YOU THiNKTHE ENGINE-GOVERNED

HIGH SPEED NEEDS ADJUSTING, CONTACT YOUR

NEAREST AUTHORIZED SERVICE CENTER/

DEPARTMENT, WHICH HAS PROPER EQUIPMENT AND

EXPERIENCE TO MAKE ANY NECESSARY ADJUSTMENTS.

THROTTLE

IDLE SPEED

LEVER

SCREW

IDLE MIXTURE VALVE

FIG, 28

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Image 25
Craftsman 917.25651 owner manual To Adjust Carburetor See Fig, Preliminary Setting, Final Setting, Acceleration Test