2001 Polaris Sportsman 400-500 DUSE and H.O. Service Manual, Page 151Get this manual
FUEL SYSTEMCARBURETION
JETTING GUIDELINES
Changes in altitude and temperature affect air density, which is essentially the amount of oxygen available for combustionIn low elevations and cold temperatures, the air has more oxygenIn higher elevations and higher temperatures, the air is less denseCarburetors are calibrated for an altitude of 0-3000 ft(0-900 meters) and ambient temperatures between +40 and +80 (+5 to +26 C)Carburetors must be re-calibrated if operated outside the production temperature andor altitude rangeThe main jet installed in production is not correct for all altitudes andor temperaturesIn addition, air screwpilot screw adjustments may be required to suit operating conditionsCAUTION: main jet that is too small will cause lean operating condition and may cause serious engine damageSelect the correct main jet carefully for elevation and temperature according to the charts in the General Specifications Chapter, or in the Owner's Safety and Maintenance Manual for each particular model