Carburetor Troubleshooting and
Adjustments
NOTE: Carburetor adjustments should be made only
after the engine is at operating temperature.
The carburetor is designed to deliver the correct
fuel-to-air mixture to the engine under all operating
conditions. The idle mixture is set at the factory and
normally does not require adjustment.
NOTE: To ensure correct engine operation at
altitudes above 1525 meters (5000 ft.), it may
be necessary to have an authorized Kohler
dealer install a special high-altitude jet kit in
the carburetor. If a high-altitude kit has been
installed, the engine must be reconverted to
the original jet size, before it is operated at
lower altitudes, or overheating and engine
damage can result.
If the engine is hard to start, runs roughly, or stalls at
low idle speed, it may be necessary to adjust or service
the carburetor. Engine must not exceed 3850 ± 100
RPM if the high speed screw is adjusted. See Figure 25.
Troubleshooting
If engine troubles are experienced that appear to be
fuel system related, check the following areas before
adjusting the carburetor.
• Make sure the fuel tank is filled with clean, fresh
gasoline.
• Make sure the fuel tank cap vent is not blocked
and that it is operating properly.
• Make sure the fuel shut-off valve is fully open.
• Make sure oil is at correct level.
• Make sure fuel shut-off valve strainer, and in-line
fuel filter (if used) are clean and unobstructed.
Clean or replace as necessary.
• Make sure fuel is reaching the carburetor. This
includes checking the fuel lines and components
for restrictions or problems. Replace as necessary.
• Make sure On-Off switch is functioning properly.
• Make sure the air cleaner element is clean and all
air cleaner components are fastened securely.
If, after checking the items listed above, the engine is
hard to start, runs roughly, or stalls at low idle speed,
it may be necessary to adjust or service the carburetor.
Screw
Figure 25. High Speed Screw.
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