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FUEL SYSTEM
CARBURETOR ADJUSTMENTS -Continued If the engine misses and backfires under load, the
high speed mixture is too lean. The high speed
adjustment screw must be turned counterclockwise
1/8 turn at a time until the condition is corrected.
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 1/8 turn at a time until the condition is
corrected.
Adjusting the Idle 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.
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.
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 (1800 RPM).
1. Governor control rod
2. Idle adjustment screw
3. Throttle stop screw
4. High speed adjustment screw
5. Fuel shut-off valve
6. Fuel line
International Cub Cadet 1000, 1200,
1250, 1450, and 1650 Tractors
Adjusting the High-Speed Adjustment Screw
Turn the high speed adjustment screw counter-
clockwise approximately two turns from the closed
position and start the engine.
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.
Be sure the choke is fully open (knob fully in)
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
satisfactory 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.
A CAUTION! Carbon monoxide fumes can
be fatal! Do not make any adjustments
to the carburetor in a confined area such
as a storage building. Move the tractor outside into
the air.
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