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23
CARBURETOR ADJUSTMENTS
WARNING
When making adjustments to the carburetor
while the engine is running, disengage the PTO
clutch and engage the brake pedal lock. Keep
clear of all moving parts and be careful of all hot
surfaces.
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.
The carburetor is adjusted at the factory and under
normal operating conditions it will not require
readjusting. The high idle is set at the factory and
cannot be adjusted. If the engine does not operate
properly and the problem appears to be fuel system
related, check the following areas before adjusting the
carburetor: Refer to MAINTENANCE section.
• Check for fuel in fuel tank
• Check fuel cap vent for blockage
• Check fuel line for pinched or obstructed areas
• Check for fuel filter blockage
• Check for a clogged air filter
If, however, the engine is hard-starting or runs roughly
or stalls at low idle speed, it may be necessary to
adjust or service the carburetor. Minor carburetor
adjustment may also be needed to compensate for
differences in fuel, temperature or altitude.
The air filter element and cover plate must be
assembled to the carburetor when running the engine.
NOTE
Carburetor adjustments should be made only
after the engine has warmed up.
Adjust the carburetor idle fuel mixture as follows:
The carburetor on the engine is low emission. It is
equipped with an idle speed adjustment screw, and an
idle mixture valve that has an adjustment limiter which
allows some adjustment (See Figure 17).
Figure 17
Start the engine and warm up approximately 5 minutes
before adjusting. With the engine running, place the
throttle control in the “SLOW” position. Rotate the
carburetor throttle lever against the idle speed screw
and hold it (See Figure 17). Turn the idle speed screw
to obtain 1300 to 1500 RPM. While still holding the
carburetor throttle lever against the idle speed screw,
turn the idle mixture valve screw (with limiter cap)
midway between limits.
Readjust the idle speed to 1200 RPM. Release the
carburetor throttle lever. Move the throttle control to the
“FAST” position. The engine should accelerate
smoothly. If it does not, readjust the idle mixture valve
slightly counterclockwise. DO NOT remove the limiter
cap. DO NOT force beyond the limit.
NOTE
Engines operated at approximately 3000 to
5000 feet (900 to 1500 meters) above sea level
may require a high altitude carburetor main jet.
If erratic performance is observed, contact your
Authorized Engine Dealer for a high altitude
main jet.
Control Adjustments
To adjust the choke control, remove the air cleaner.
Move the choke control to the full choke position. The
carburetor choke should be completely closed (See
Figure 18). If not, loosen the casing clamp screw.
IDLE
SPEED
SCREW
CARBURETOR
THROTTLE
LEVER
IDLE
MIXTURE
VALVE
LIMITER
CAP