22
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. 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 open air.
The carburetor on the engine is low emission. The high
idle is set at the factory and cannot be adjusted. The
carburetor is equipped with an idle speed adjustment
screw, and an idle mixture valve that has an adjust-
ment limiter which allows some adjustment.
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 assem-
bled 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:
1. Start the engine and warm up approximately 5
minutes before adjusting.
2. With the engine running, place the throttle control
in the “SLOW” position.
3. Rotate the carburetor throttle lever against the idle
speed screw and hold it (See Figure 17).
4. Turn the idle speed screw to obtain 1200 RPM.
5. Turn the idle mixture valve screw (with limiter cap)
for cylinder #1 midway between limits. Then set
the cylinder #2 mixture valve midway between
limits, while holding the carburetor throttle lever
against the idle speed screw. See Figure 17.
Release the carburetor throttle lever. Move the throttle
control to the “FAST” position. The engine should
accelerate smoothly. If it does not, contact your Cub
Cadet dealer. DO NOT remove the limiter cap. DO NOT
force beyond the limit.
Figure 17
NOTE
Engines operated at approximately 3000 or
higher (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 installation of a
high altitude main jet.
IDLE
SPEED
SCREW
CARBURETOR
THROTTLE
LEVER
IDLE
MIXTURE
VALVES
LIMITER
CAP
CYL #2
CYL #1
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