Craftsman 917.257711 Owner's Manual page 25

E ADJUSTMENTS
TO ADJUST CARBURETOR
(See Figs. 40 & 41)
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 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.
IMPORTANT: DAMAGE TO THE NEEDLES AND THE
SEATS IN CARBURETOR MAY RESULT iF SCREW IS
TURNED tN 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 (counterclock-
wise) 1-.1/4 to 1-1/2 turns.
FINAL SETTING -
o 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 controt lever in slow (_) position, hold
throttle lever against idle speed screw and adjust idle
speed screw to obtain 1200 to 1400 RPM.
While still 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 tever.
ACCELERATION TEST-
o Move throttle control lever from stow (,_!,) to fast (,t_)
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.
High speed stop is factor}, 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. tF YOU THtNKTHE 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
SCREW
iDLE MIXTURE
SCREW
THROTTLE
LEVER
FIG. 40
IDLESPEED __(, '_
SCREW
__ )_
THRO E MIXTURE
LEVER SCREW
F|G. 4t
25