Class Descriptions for the 2012 to 2013 season.

Junior stock: This class is for Junior competitors aged from 10-13 years of age competing on ISR specified sleds. Legal sleds for this class are as follows: Arctic Cat; Puma/Jag 340 and Z 370, Polaris; Indy Lite 340, Indy 340, Indy 340 Deluxe and 340 Edge, Si-Doo; Formula S368, MXZ 380, Freestyle 300, and Tundra 300, Yamaha; Ovation 340. This is a beginner class on limited horsepower sleds with little or no changes allowed from stock production. This class has a speed limit that may be enforced if track size dictates it for safety purposes. Rules are found in the ISR rulebook for 2012 on pages 135-136.

Junior I Sprint: This is a modified class for Junior competitors aged 12-15. It utilizes an open chassis purpose built sled and a stock air cooled engine of a 380 cc maximum. Engines must come from the following production brands, Arctic Cat 370, Ski Doo 380, Polaris 340, and Yamaha 340. Engine must be used in stock trim; the factory �wye pipe must be used. The air box may be removed and the exhaust system after the wye pipe may be modified. Rules for this class are found on pages 131 and 132 of the 2011 ISR rulebook.

Junior II Sprint: This is a modified class for Junior Competitors aged 14-17. It utilizes an open chassis purpose built sled and a stock air cooled engine of a 600 cc maximum. Engines must be stock qualified 600 cc or less displacement engines from current production sleds. Rules for this class are found on page 132-133 of the 2011 ISR rulebook.

Junior I F-500: This class is for competitors aged 11-13 utilizing a legal F-500 sled. The sled must be restricted in the following manner to be able to compete. The gear ratio is fixed at 15/39 and a carburetor restrictor plate must be used between the carburetor mounting boot and the cylinder. Restrictor plates are available from the USSA Director of Competition and have a deposit required. This class allows a family with an F-500 sled the ability to run the unit in both adult and junior classes. Rules for this class are found on the USSA website.

Junior II F-500: This class is for competitors aged 14-15 utilizing a legal F-500 sled. The sled will compete in legal trim for the adult F-500 class. This class allows a family with an F-500 sled the ability to run the unit in both adult and junior classes. Rules for this class are found on the USSA website.

F-500: This class is an entry level budget class, utilizing 1989 to 1992 Polaris Indy 500 Chassis and engines. The class offers close competition for many riders at an affordable price. Chassis are allowed limited modifications to improve handling, and hoods, seats, dashboards, and other cosmetic items are allowed to be changed or modified to enhance creativity and uniqueness. Rules for this class are found on page 74 of the ISR rulebook for 2012. Please review as several new rules and limitations apply.

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