Craftsman 917.270631 - Manual (Page 26)

TO ADJUST CARBURETOR
NOTE: The carburetor on this engine is
low emission. It is equipped with an idle
fuel adjusting needle with a limiter cap,
which allows some adjustment within the
limits allowed by the cap. Do not attempt
to remove the limiter cap. The limiter cap
cannot be removed without breaking the
adjusting needle.
The carburetor lias been preset at the fac­
tory and adjustment should not be neces­
sary. However, minor adjustment 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) decreases the supply of fuel to
the engine giving a leaner fuel/air mixture.
Turning the idle mixture valve out
(counterclockwise) 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.
PRELIMINARY SETTING
<» Air cleaner assembly must be assem­
bled to the carburetor when making car­
buretor 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 posi­
tion. With finger, rotate and hold throttle
lever against Idle speed screw. Turn idle
speed screw to attain 1750 RPM.
® While still holding throttle lever against
idle speed screw, turn idle mixture valve
full travel clockwise then counterclock­
wise 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 to
fast position. If engine hesitates or dies,
turn idle mixture valve out (counter­
clockwise) 1/8 turn. Repeat test and
continue to adjust, if necessary, until
engine accelerates 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 set­
ting can be dangerous, if you think the
engine-governed high speed needs
adjusting, contact your nearest authorized
service center, which has proper equip­
ment to make any necessary adjustments.
Idle Speed
Screw
Throttle
Lever
26