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^^WARNING
To avoid injury or an accident, be sure the
brake pedal is in the locked position, trans -
mission is in neutral, and any equipment is dis -
engaged before starting engine to make car¬
buretor adjustments.
A WARNING
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.
■^note
The tractors covered in this manual will be
equipped with either a fixed-jet or an
adjustable carburetor. The difference be¬
tween the carburetors is that the fixed-jet
carburetor does not have a main fuel adjust -
ment; therefore the fixed-jet carburetor has
only two adjustment screws.
The carburetor Is adjusted at the factory, and under
normal operating conditions. It will not require
readjusting. However, if the engine does not operate
properly, what may appear to be a faulty carburetor ad -
justment is in many cases a clogged air filter. This
possibility should be ruled out before attempting to
readjust carburetor. Refer to "MAINTENANCE" sec -
tion in this manual.
To prevent possible damage to the carburetor nee -
dies, be very careful closing the carburetor needles
before basic adjustments are made. Improper adjust -
ment of the carburetor may result in engine damage.
ADJUSTING THE HIGH-SPEED ADJUSTMENT
SCREW (Tractors With Adjustable Carburetor Only)
Gently turn the high-speed adjustment screw
clockwise until closed. Do not overtighten. (See Fig -
ure 31.) Next turn the high-speed adjustment screw
counterclockwise one and three eighths (1-3/8) turns
from the closed position and start the engine.
Be sure the choke is fully open (choke control knob
fully In) when adjusting the high-speed adjustment
screw.
If the engine misses and backfires under load, the
high-speed mixture is too lean. The high-speed ad -
justment screw must be turned counterclockwise 1/8
turn maximum until the condition is corrected.
1
Figure 31. Tractors With Adjustable Carburetor
1. High-Speed Adjustment Screw
2. Idle Fuel Adjustment Screw
3. Idle Speed Adjustment Screw
Figure 32. Tractors With Fixed-Jet Carburetors
1.
Idle Fuel Adjustment Screw
2.
Idle Speed Adjustment Screw
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 maximum until the condition is
corrected.
20
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