1973 and older HR port sleds may compete.
- Must be a production line model offered to the public in 1973 and older with a fan cooled engine.
- Example : Arctic Cat / Puma, Cheetah, Panther, Lynx with and 1973 or older Arctic Cat fan cooled engine. Ski Doo / NTN, Olympic, Elan with any HR port fan cooled engine 1973 and older.
- Fan cooled engine only with HR port
- Engine must be available for model year.
- Example: Arctic Cat may run / Kohler, Sachs, JLO, Kawasaki or Hirth of any CC
- Over boar allowed to .060
- No Porting / stock ports
- Stock carb or float type replacement will be allowed. NO flat slides, carb bore must be smaller than the port.
- Stock muffler only.
- Point ignition only, no CDI
- No Reed or Rotary valves
- Stock suspension only
- Carbides allowed.
- Shocks are permitted on skis.
- Stock secondary only.
- Stock clutch or 94c Duster / Power block drive clutches are permitted.
- ¾ inch lug track / stock length for model permitted.
- Seat must be stock appearing
- No adjustable handlebars
- Skis must be steel
- Studs allowed, 3/8 max above lug.
- Ski spreaders allowed, 3 inch max.