Cub Cadet 108 Operator's Manual page 13

FUEL SYSTEM
If the engine shows a sooty exhaust and is sluggish
under load, the high speed mixture is too rich. The
high speed adjustment screw must be turned
clockwise 1/4 turn at a time until the condition is
corrected.
CARBURETOR ADJUSTMENTS -Continued
A
CAUTION! Be sure the brake pedal is in
the locked position, transmission is in
neutral, and the mower is disenga~d
before adjusting the carburetor.
Adjusting the Idle Adjustment Screw
Adjusting the High-Speed Adjustment Screw
After the high speed adjustment screw is adjusted,
it may be necessary to readjust the idle adjustment
screw as each affects the other.
Turn the high speed adjustment screw counter-
clockwise approximately two turns from the closed
position and start the engine.
Close the idle adjustment screw to its seat by
turning it clockwise; then open it one turn. Start
the engine and operate it at fast idling speed
(without any load) until thoroughly warm.
Be sure the choke is fully open when adjusting.
After the engine has reached normal operating
temperature, place the throttle lever in the fast
position and turn the high speed adjustment screw
clockwise to the leanest mixture that will allow
sat i sf actory acceleration and steady governor
operation. Then, turn counterclockwise to the
richest mixture that allows satisfactory operation.
The difference between the rich and lean points is
about 1/2 turn. Set the mixture to the rich end of
this range.
While the engine is running at fast idle speed, it is
advisable to screw in the throttle stop screw a few
turns to keep the engine from stopping when the
throttle lever is moved to the fully retarded
"SLOW" position. The engine will then be idling at
a fairly high speed and the throttle stop screw can
be backed out a little at a time until the desired
idle speed is obtained.
If the engine misses or rolls while backing out the
throttle stop screw, the idle adjustment screw may
be adjusted in or out until the engine operates
smoothly. Speed up the engine for a few seconds;
then recheck the idle adjustment. A slight adjust-
ment in or out will give the smoothest idle.
If the engine misses and backfires under load, the
high speed mixture is too lean. The high speed
adjustment screw must be turned counter-clock-
wise 1/4 turn at a time until the condition is
corrected.
PREPARING THE TRACTOR FOR EACH DAY'S WORK
Check the crankcase oil level and add new oil if necessary. See pages 34 and 35.
Clean the air cleaner element if necessary. See page 21.
Inspect the tires for general condition. See page 26
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