Polaris 800 Pro X Owner's Manual page 86

MAINTENANCE
Carburetor
The number stamped in the end of the main jet indicates the jet size.
The jet installed at the time of manufacture is not necessarily correct
for your elevation. It's your dealer's responsibility to make sure the
correct main jet is installed.
Operating the snowmobile with incorrect jetting can result in serious
engine damage. Have your Polaris dealer perform all carburetor
adjustments to ensure all adjustments are done correctly.
The frequency at which the carburetors are synchronized or balanced is
important. Properly adjusted carburetors can greatly improve engine
performance, fuel economy, engine life, and reliability.
If you notice any of the following conditions, the carburetor may need
adjustment:
S Hard starting
S Poor idle
S Overheated pistons and cylinder walls
S Plug fouling
S Poor engine response to various throttle valve openings
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CAUTION