1985 and older fan cooled twins up to 300cc
- 1985 and older models may compete
- 300cc and under twin cylinder engine displacement may compete.
- Studs allowed
- Carbides allowed
- No jackshaft models
- Any type or brand of replacement track may be used, ¾ lug max.
- Suspensions may be interchanged up to model year 1985
- OEM stock drive clutch or Powerblock / 94c duster
- Stock driven clutch.
- Steel skis only.
- Stock appearing seat
- Float type carburetors allowed, bore must be smaller than port.
- Ski spreaders allowed, 3 inch max.