Craftsman 917256430 tractor

User Manual - Page 27

For 917256430.

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SERVICE AND ADJUSTMENTS
ENGINE PRELIMINARY SETTING-
TO ADJUST THROTTLE CONTROL CABLE
(See Fig. 33)
The throttle control has been preset at the factory and
adjustment should not be necessary. Check adjustment as
described below before loosening cable. If adjustment is
necessary, proceed as follows:
With engine not running, move throttle control lever
from slow (_l,) to choke (1\i) position. Slowly move
lever from choke (IX!) to fast (,_) position.
Checkthat holes "A" in governor controI lever and hole
in governor plate I!ne-up. tf holes "A" are not aligned,
loosen clamp screw and move throttle cable until holes
are aligned, Tighten clamp screw securely.
GOVERNOR
CONTROLLEVER GOVERNOR
CONTROLPLATE
\\
o
HOLES"A" CLAMP THROTTLE
SCREW CABLE
FIG. 33
TO ADJUST CARBURETOR (See Fig. 34)
NOTE: The carburetor on this engine islow emission. Itis
equipped with an idle fueI adjusting needle with a limiter
cap, which allows some adjustment within the limits al-
lowed by the cap. Do not attempt to remove the limiter cap.
The limiter cap cannot be removed without breaking the
adjusting needle.
The carburetor has been preset at the factory and adjust-
ment should not be necessary. However, minor adjust-
ment may be required tocompensate for differences infuel,
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 Ieaner 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.
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).
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 iever against idle speed
screw. Turn idle speed screw to attain 1750 RPM.
While still holding throttle lever against idle speed
screw, tum idle mixture valve full travel clockwise then
counterclockwise until engine runs rough. Turn valve
to a point midway between those two positions. Re-
lease throttle lever.
ACCELERATION TEST -
Move throttle controi lever from slow (,_) to fast (,f_)
position. If engine hesitates or dies, turn idle mixture
valveout (counterclockwise) 1/8turn. Repeattestand
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.
THROTTLE IDLE SPEED
LEVER SCREW
\\
IDLE MIXTURE
VALVE WITH
LIMtTER
FIG. 34
27
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