Polaris 120 Owner's Manual For Maintenance And Safety page 62

Maintenance
Carburetor
Proper carburetor adjustment is critical, since a mixture too lean (too
much air, too little fuel) will result in overheating of the combustion
chamber causing pre-ignition of the fuel. This results in piston
burning, bearing failure, or complete engine failure. A lean mixture
can be the result of fuel line restrictions, foreign matter in the
carburetor, etc. A mixture too rich (too much fuel, too little air) is also
unfavorable because it can foul plugs and cause generally poor engine
performance.
All carburetors have been pre-set at the factory for adequate fuel
supply. Higher altitude operation may require different adjustment and
settings. The number stamped in the end of the main jet indicates the
jet size that was installed at the time of manufacture. For questions
about optional jetting for conditions in your area, see your Polaris
dealer.
1. Engine
2. Carburetor
Correct setup provides engine RPM
within its given power band at full
throttle settings and also provides
maximum efficiency and operation
at all other throttle openings. See
your dealer for carburetor
adjustments, which may include the following:
S Carburetor component changes for specific altitude and ambient
temperatures;
S Choke adjustment;
S Air screw settings, if applicable;
S Idle RPM adjustments;
S Throttle safety switch checks and servicing;
S Throttle block to throttle flipper clearance adjustment
CAUTION
Improper carburetor adjustments can result in safety hazards as
well as serious engine damage. We recommend that all
carburetor adjustments be performed by your Polaris dealer.
ADULT SECTION
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