To adjust carburetor (see figs. 32 and 33), Service and adjustments – Craftsman 917.252560 User Manual
Page 24
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SERVICE AND ADJUSTMENTS
TO ADJUST CARBURETOR
(See Figs. 32 and 33)
The carburetor has been preset at the factory and adjust
ment should not be necessary. However, minor adjust
ment maybe required iocompensatefordifferences in fuel,
temperature, altitude or load. If the carburetor does need
adjustment, proceed as foHows:
In general, turning the mixture screw
in
(clockwise) de
creases the supply of fuel to the engine giving a leaner fuel/
air mixture. Turning the mixture screw
out
(counterclock
wise) increases the supply of fuel to the engine giving a
richer fuel/air mixture.
MViPORTANT:
DAMAGE TO THE NEEDLES AND THE
SEATS IN CARBURETOR MAY RESULT IF SCREW IS
TURNED IN TOO TIGHT
PRELIMINARY SETTING -
“ Be sure you have a clean air filter, and the throttle
control cable and choke are adjusted properly (see
above),
•
With engine off turn idle mixture screw
in
(clockwise)
closing it finger tight and then turn
out
(counterciock-
wise) 1 -1/4 to 1-1/2 turns.
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.
. With throttle control lever in slow (*^) position, hold
throttle lever against idle speed screw and adjust idle
speed screw to obtain 1200 to 1400 RPM,,
“ While stii! holding throttle lever against idle speed
screw, turn idle mixture screw
in
(clockwise) until
engine begins to die and then turn
out
(counterclock
wise) until engine runs rough. Turn screw to a point
midway between those two positions.
“ Continue to hold throttle lever against idle speed screw
and adjust idle speed screw to obtain 900 to 1200 RPM.
Release throttle lever.
ACCELERATION TEST -
*
Move throttle control ¡ever from slow (*®) to fast (•%?)
position, if engine hesitates or dies, turn idle mixture
screw
out
(counterclockwise) 1/8 turn. Repeat test
and continue to adjust, if necessary, until engine accel
erates smoothly.
factory adjusted. Do not adjust -
High speed stop is
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 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
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