2003 Polaris Universal ATV Owners Manual - Page 111

Adjustments Carburetor MAINTENANCE AND LUBRICATION IMPORTANT: Your Polaris ATV is calibrated at the factory for optimal performance at altitudes ranging from zero to 6,000 feet (1800 m) and temperatures of +40 degrees F. (4 degrees C.) or higher. Above 6000 feet (1800 m) the engine air/fuel mixture becomes overly rich and the engine loses approximately 3% of its power for each 1000-foot (304.8 m) increase in elevation. Although this power cannot be regained, adjustments to the carburetor and drive system can be made to allow more efficient operation. Optional jets, available from your Polaris dealer, are required for operation above 6,000 feet and temperatures below +40 degrees F. (4 degrees C.) NOTE: Continuous operation of the engine without proper jetting when required can cause poor performance, overheating or engine damage. See your Polaris dealer for more information about jetting the ATV for conditions in your area. 2-Cycle Engines If the engine idle speed is not satisfactory, and all other conditions are favorable, the carburetor can be adjusted. 1. Warm up the engine by running the vehicle for approximately five minutes. 2. Place the transmission in gear with the parking brake applied. 1 3. Adjust the carburetor idle screw (1) either in or out until the desired idle RPM is reached. Turning the screw in (clockwise) will raise RPM. Turning the screw out 2 (counterclockwise) will lower RPM. The following variations apply to air screw (2) adjustment for 2-cycle engines: S For improving cold weather start and reducing audible detonation noise, the air screw can be closed from 1/2 to 1 turn by turning the screw clockwise. S During hot weather and/or high altitude operation the air screw can be adjusted for smoother operation by turning the screw counterclockwise for approximately 2 turns. 109