To adjust carburetor (see fig. 32), Service and adjustments – Sears 917.257643 User Manual
Page 25
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SERVICE AND ADJUSTMENTS
TO ADJUST CARBURETOR (See Fig.
32
)
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 idie mixture valve out (counter
clockwise) Increases the supply of fuel to the engine giving
a richer fuel/alr 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 (•m) position. With
finger, rotate and hold throttle lever against idie speed
screw. Turn idle speed screw to attain 1750 RPM ,
•
While still holding throttle lever against idle speed
screw, turn idle 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 positions. Release throttle lever.
ACCELERATION TEST -
• Move throttle control lever from slow (-m) to fast (*^)
position. 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. OVERSPEEDING THE ENGiNE-ABOVE
THE
FACTORY
HIGH
SPEED
SETTING
CAN
BE
DANGEROUS. IF YOU THINK THE ENGINE-GOVERNED
HIGH SPEED NEEDS ADJUSTING, CONTACT YOUR
NEAREST
AUTHORIZED
SERVICE
CENTER/
DEPARTMENT, WHICH HAS PROPER EQUIPMENT AND
EXPERIENCE
TO
MAKE
ANY
NECESSARY
ADJUSTMENTS
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