USSA Class Description for the 2010 to 2013 season.
Junior Novice: 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, Skidoo; 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 2010 on pages 117-118.
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 119 and 120 of the 2010 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 120 of the 2010 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 pages 59 and 60 of the ISR rulebook for 2010, or on the USSA web site.
Sportsman 600: This is a regional class offered by USSA utilizing 1983 to 2000 production chassis and engines. This class is limited to 600 cc liquid cooled engines maximum displacement. It is designed as a budget, introductory class and is titled “Sportsman” to indicate that while it observes many stock restrictions, it does allow some builder creativity. The class is stepping stone class to full mod chassis classes, and offers fast racing, good handling, and excitement. Rules for this class are found on the USSA web site.
Combo: This class is provided as an entertainment class for riders of the F-500 division and the Sportsman division. Sleds must remain legal for their base class when they compete in this class. The class pits the smaller displacement, but lighter, F-500 sleds against the Sportsman 600 powerhouses. In addition to the opportunity to run a second class for these budget sleds, track size, configuration, and driver ability allow the class to offer unbelievable racing excitement. Refer to the USSA web site for individual class rules
.
LTD 500: This class started as a regional class in USSA, but now is an accepted ISR class for stock engine participation. This class requires a maximum displacement stock 500 cc liquid cooled engines and “wye” pipe but allows exhaust modifications and an open, purpose built chassis. The class was created to offer a reprieve from the existing stock classes offered prior to 2010 that required stock engines and stock chassis, but allowed for extremely expensive chassis modifications that were not productive to garnering large groups of riders due to the expenses involved. The class allows 2009 and previous stock class sleds a place to race, along with the purpose built Limited class sleds. This class is quite successful and is the base for the Ltd 600 class. Rules can be found in the ISR book on pages 60 and 61.
LTD 600: This class started as a regional class in USSA, but now is an accepted ISR class for stock engine participation. This class requires a maximum displacement stock 600 cc liquid cooled engine and “wye” pipe but allows exhaust modifications and an open, purpose built chassis. The class was created to offer a reprieve from the existing stock classes offered prior to 2010 that required stock engines, stock chassis, but allowed for extremely expensive chassis modifications that were not productive to garnering large groups of riders due to the expenses involved. The class allows 2009 and previous stock class sleds a place to race, along with the purpose built Limited class sleds. This success of the LTD 500 class is the base for the Ltd 600 class. Rules can be found in the ISR book on page 61.
Sprint Stock 600 Fan: This is a USSA regional class using a purpose built sprint chassis and requiring a stock production fan cooled engine of 600 cc maximum. This class is designed to be an introductory Sprint competition level. The engine is required to be stock, to reduce costs, and to allow the build to concentrate on chassis design and handling to be successful. The class rules are found on the USSA web site.
Pro Sprint 600: This modified class uses air cooled engines of 600 cc maximum displacement and limited carburetion. This class is extremely fast for the engine package and offers an open field for chassis and engine builder creativity. This class has the same speed potential on smaller tracks as Champ 440 sleds and sometimes “promoter option” classes are created to allow the two classes to compete. The builders in this class are highly talented in both suspension geometry and engine development. Rules for this class are found on pages 57 and 58 of the ISR rulebook for 2010.
Pure Stock 600: This is a new class that requires a 600 cc maximum stock production 2010 model specific sled to be used in stock trim. Modifications are extremely limited, and are limited to minor suspension tie down, clutch and carb tuning, and specified carbide limits. This class is designed to return stock class racing to a “stock” category and not the highly modified units that competed as “stock” sleds in the past. This is the inaugural year for the class. It is ISR approved and rules are found on pages 55 and 56, and are also on the USSA web site.
Champ 440: Champ 440 is the Premier USSA class; it utilizes 440 cc maximum liquid cooled engines with restricted carburetors and an open exhaust. Chassis limitations are primarily weight and width. This high powered open design class is the base for the Worlds Championship class and is recognized throughout the snowmobile race world as the “professional” class of competition. Rules for this class are available in the ISR rulebook for 2010 on pages 56 and 57.
Open 600: This class is a USSA regional class that offers the use of an open concept chassis and 600 cc liquid cooled power plant. The engine may be modified, but is limited in carburetion to control on track safety. The class is constantly monitored for speed and safety and can be further restricted at any time. This class is offered in USSA and at other select events. Rules for this class are available in the 2010 ISR book on pages 58 and 59.
Class Structure
2010 -2013 Season Rules Format
1. Oval Junior Novice 11-13 Present rules ISR Spec sleds
2. Oval Junior F-500 11-13 F-500 with restrictor plate and 15/39 gear ( call Director of Competition for plate)
3. Oval Junior F-500 14-15 F-500 no restrictions
4. Oval Junior I Sprint Present rules and trial F-500 with restrictor plate (F-500 13-15 year old riders) F-500 may be dropped at any time
5. Oval Junior II Sprint Present rules
6. F-500 Present rules
7. Sportsman 600 Present rules
8. Combo Sportsman and F-500/ present rules
7. LTD 500 Present rules, includes old Stock 500 legal sleds
8. LTD 600 New rules for 2010, includes old 600 Stock and Super stock legal sleds
9. Sprint 600 Fan stock New rules for 2010, stock fan cooled engines without modification, open chassis
10. Semi Pro Champ Present rules
11. Pro Sprint 600 All present mod rules Sprint classes
12. Pure Stock 600 ISR Pure Stock rules, new for 2010
13. Champ 440 Present rules till rules deadline
14. 600 open ISR rules / 4 stroke included/ carb restricted
15. Exhibition Stock Promotional event not offered at all sites. Details to follow if and when class is debuted.
Click Here for Printable Version of Class Structure
