Sears Craftsman 917.257720 - Manual (Page 25)

SERVICE AND ADJUSTMENTS
ENGINE
TO ADJUST THROTTLE CONTROL CABLE
(See Fig. 38 & 39)
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 to
fast ) position.
« Checkthat speed control lever is against stop screw. If
it is not, loosen casing clamp screw and pull throttle
cable until lever Is against screw. Tighten clamp screw
securely. ‘
TO ADJUST CARBURETOR (See Fig. 40)
The carburetor has been present at the factory and adjust-
mentshould not be necessary. However, minoradjustment
may be required to compensate for differences in fuel,
temperature, altitude or load. If the carburetor does not
need adjustment, proceed as follows:
In general, turning the adjusting needles in (clockwise)
decreases the supply of fuel to the engine giving a leaner
fuel/air mixture. Turning the adjusting needles out (coun­
terclockwise) increases the supply of fuel to the engine
giving a richer fuel/air mixture.
IMPORTANT:
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 Is adjusted properly (see above).
• With engine off turn idle fuel adjusting needle in (clock­
wise) closing it finger tight and then turn out (counter­
clockwise) 1-1/4 turns.
• Turn main fuel adjusting needle in (clockwise) closing
fingertight andthen turn out (counterclockwise) 1 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.
• With throttle control lever in fast ( ^ ) position, turn
main fuel adjusting needle in (clockwise) until engine
begins to die then turn out (counterclockwise) until
engine runs rough. Turn needle to a point midway
between those two positions.
• Idle speed setting - With throttle control lever in slow
(•«») position, engine should idle at 1400 RPM. If
engine idles too slow or fast, turn idle speed adjusting
screw in or out until correct idle is attained.
• Idle fuel needle setting - With throttle control lever in
slow { - m ) position, turn idle fuel adjusting needle in
(clockwise) until engine begins to die and then turn out
(counterclockwise) until engine runs rough. Turn needle
to a point midway between those two positions.
• Recheck idle speed. Readjust if necessary.
ACCELERATION TEST -
• Move throttle control lever from slow (•«») to fast (^)
position. If engine hesitates or dies, turn idle mixture
screw out (counterclockwise) 1/8 turn. 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
ENGINESPEED. 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.
IDLE SPEED
ADJUSTING
SCREW ---
IDLE FUEL
ADJUSTING
NEEDLE
MAIN FUEL
ADJUSTING
NEEDLE
25
FIG. 40