General Stock Rules
In stock and stock based classes no changes or modifications are allowed unless specifically allowed by these rules. If these rules do not specifically allow a change or modification, then it must be assumed that the change or modification is not allowed.
- The engine must be OEM for that model.
- Engine, engine mounts and exhaust must remain in original OEM for that model locations (of the chassis).
- Any internal modifications are allowed to the engine.
- NO external modifications allowed. Engine must remain OEM for the model appearance.
- Engine bore size may be increased up to 0.060 inches over stock bore. Must maintain OEM stroke for that engine.
- After market pistons allowed.
- Intake concept (for the engine) must be maintained (piston, port, reed valve, etc.).
- Any round slide carb from a stock qualified snowmobile is allowed. Flat slide carbs are not allowed. Air intake silencers (air boxes) may be removed.
- Cooling system (for engine) must be maintained and fully functioning (i.e. free-air, fan, etc.).
- Must be naturally aspirated.
- Unaltered OEM exhaust system must be used for year, make, and model. (NOTE: Factory update silencer may be used on 1975 Merc S/T.)
- Ignition system must be OEM for engine or aftermarket ignition of the same concept.
- Any snowmobile brand OEM primary clutch allowed.
a. Any button style non roller secondary clutch is allowed.
- Brake components may be replaced. Must be commercially available and not modified, may be relocated. Any externally visible components must be shielded.
- Maximum ski widening is 3 inches.
- Unlimited amounts of studs. Must not exceed 3/8" from the highest point on the track. Track must be 3/4" lug or less.
- Unlimited sharpened area on ski runner.
- Sled must have a stock appearing cowl with at least 4" numbers appearing on both sides.
- No chassis modifications.
a. Chassis modifications include relocation of chain case, changing angles of spindles, widening the bulk head, addition of jackshaft and tunnel must be OEM for the model.
- Any type leaf sprung, with 2" arch and must be functional. (Should move when the leaf spring is
stepped on by a person weighing between 200 - 250 pounds.)
- No alcohol fuel is allowed.
- Any stock suspension 1985 or older, no aftermarket suspensions. No less than 3 inch overall track length than what came with that model.
- Remote adjustors are not allowed. (A remote adjustor is a system which allows the manual or automatic raising or lowering of the front skid/track while sled is in motion.) A manual adjustor is allowed, such as a limiter strap, eyebolt style adjustor.