Carburetion

Content Source: 2020 550 Indy 144 Owner’s Manual (9929781 R01) > Operation Chapter

IMPORTANT

The Owner's Manual for this vehicle contains warnings, instructions and other information you must read and fully understand before safely riding or performing maintenance on this vehicle.Always follow the warnings and instructions in Owner's Manual.

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Carburetion

NOTICE

Making non-recommended adjustments could result in vehicle or engine damage as well as denial of warranty claims. Your Polaris dealer can assist with any carburetor adjustments.

Proper carburetor adjustment is critical. A lean mixture (too much air, too little fuel) may result in piston burning, bearing failure, or complete engine failure. A rich mixture (too much fuel, too little air) may foul plugs and cause generally poor engine performance.

A lean mixture may be caused by things like fuel line restrictions, foreign matter in the carburetor or clogged fuel filters. A rich mixture may be caused by snow build-up on the pre-filter in the air intake system. Either condition may be caused by improper carburetor adjustment.

Jetting Guidelines

Changes in altitude and temperature affect air density, which is the amount of oxygen available for combustion. In low elevations and cold temperatures, the air has more oxygen. In higher elevations and higher temperatures, the air is less dense.

The carburetors are calibrated for an altitude of 0-2000 ft. (0-600 m) and ambient temperatures of -15° to +5° F (-26° to -15° C). Carburetors must be re-calibrated if the snowmobile is operated outside this production temperature and/or altitude range. The main jet installed in production is not correct for all altitudes and/or temperatures. See Carburetor Adjustments for more information.

NOTICE

A main jet that’s too small will cause a lean operating condition and may cause serious engine damage. Jet the carburetors carefully for elevation and temperature according to the jetting charts.

TIP

It’s the owner’s responsibility to ensure that the correct jets are installed in the machine for a geographical area. Be very careful when jetting down in warm weather. As the weather turns colder it will be necessary to re-jet to prevent engine damage. When selecting the proper main jet always use the lowest elevation and temperature that is likely to be encountered.