General Stock Rules
  1. The engine must be OEM for that model.
  2. Engine, engine mounts and exhaust must remain in original OEM for that model locations (of the chassis).
  3. Any internal modifications are allowed to the engine.
  4. NO external modifications allowed. Engine must remain OEM for the model appearance.
  5. Engine bore size may be increased up to 0.060 inches over stock bore. Must maintain OEM stroke for that engine.
  6. After market pistons allowed.
  7. Intake concept (for the engine) must be maintained (piston, port, reed valve, etc.).
  8. 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.
  9. Cooling system (for engine) must be maintained and fully functioning (i.e. free-air, fan, etc.).
  10. Must be naturally aspirated.
  11. Unaltered OEM exhaust system must be used for year, make, and model. (NOTE: Factory update silencer may be used on 1975 Merc S/T.)
  12. Ignition system must be OEM for engine or aftermarket ignition of the same concept. Any snowmobile brand OEM primary clutch allowed.
  13. Any button style non roller secondary clutch is allowed.
  14. Brake components may be replaced. Must be commercially available and not modified, may be relocated. Any externally visible components must be shielded.
  15. Maximum ski widening is 3 inches.
  16. Unlimited amounts of studs. Must not exceed 3/8" from the highest point on the track. Track must be 3/4" lug or less.
  17. Unlimited sharpened area on ski runner.
  18. Sled must have a stock appearing cowl with at least 4" numbers appearing on both sides.
  19. No chassis modifications. 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.
  20. 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.)
  21. No alcohol fuel is allowed.
  22. Any stock suspension 1985 or older, no aftermarket suspensions. No less than 3 inch overall track length than what came with that model.
  23. 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.

500 Fan IFS (500 pure stock)

Any production 1997 and older, fan cooled, independent suspension 500cc or less general safety rules. General safety rules apply
Engine: No internal or external mods. May not add a carb to a single carb sled. Factory stock ignition only. No boring carbs and no replacing with different make or model carb. Mods allowed are a .020 overbore, oil injection deleate, and airbox removal.

Exhaust: Must be original unaltered factory stock exhaust, including headpipe. Must be OEM for year, make and model.

Front Suspension: All locating points must remain in stock location, all trailing arms, radius rods, a-arms, sway bars, spindles, and bell cranks must be OEM for the model. No widening kits. May shorten, slug, or replace the OEM shocks to lower the chassis ride height. No fox, float type shocks. May use gas/remote resevoir shocks. Front shock springs may be shortened or replaced. Any style ski is allowed. Unlimited carbide.

Rear Suspension: All components to remain factory stock with exception of springs/shock. May lower rear skid to maintain chassis ride height. May replace or modify existing shocks/springs. Suspension mounting points my be changed.

Track: OEM tracks only. No R-tracks. Unlimited studs, clips, and lube system.

Body: Hood and pan must remain stock. Seat may be altered or replaced. Fuel tank may be altered or replaced. Any handlebar allowed. Brake upgrade allowed. May convert to hydro brakes. All trim may be removed, Headlight may be removed. Tape headlight with plastic to prevent shards

Clutches: Any OEM clutch allowed. No aftermarket, or billet clutches.

ISR F-440 FAN CLASS RULES STOCK SLED GENERAL REQUIREMENTS

  1. All sleds must comply with the GENERAL SECTION SLED/EQUIPMENT REQUIREMENTS & REGULATIONS.
  2. The sled must have original OEM engine, frame, cowl, suspension, and variable speed converters supplied by the manufacture for that model.
  3. Sleds competing in this class must be 1996 or older 440 CC maximum engine volume. (Fan Cooled only)
  4. **Only hydraulic welded body, non-revalvable, non-repairable shocks will be used in the front suspension and chassis. If a legal chassis and engine stock production sled originally came with a gas charged, re-valvable shock, the shocks must be replaced with a hydraulic, welded body shock. Shock may not be altered in any way. This is a method of cost control for this class.

ENGINE

  1. No component of the engine may be altered, changed, or enlarged from the engine manufacturer’s original Stock specifications, nor may any additional components be added to the engine.
  2. Blueprinting will not be allowed. No removal of material whatsoever will be allowed. This is to include polishing, port matching, deburring, glass or sand blasting surfaces or material removal for the purposes of engine balancing or other reasons.
  3. Must retain stock bore and stroke.
  4. OEM or OEM style replacement pistons are allowed for replacement. Pistons may be up to .020 (.5mm) overbore. Pistons must be OEM or SPI replacements only. No Wiseco pistons allowed.
  5. Aftermarket engine gaskets may be used, but original factory spec thickness is required. No changes in engine dimensions can be made by gasket adjustments.
  6. Only original type gasket materials allowed for engine assembly.
  7. No engine update or performance kits/options allowed.
  8. Oil injection pumps may be removed.
  9. Only OEM carburetors allowed. Must be OEM for year, make and model.

WINDSHIELD

  1. Windshields may be removed or shortened, if used, must be mounted in the OEM mounting location.

    2. SEAT/FUEL TANK

  2. Seat/fuel tank must remain OEM for the model. Seat may be recovered.
  3. Seat must maintain original profile as produced. No alterations to stock seat except for mounting fasteners and location allowed.

BRAKES

  1. Brakes may be changed or altered but must remain in the stock location.

    2. FRONT SUSPENSION SPRINGS

  2. Any snowmobile suspension spring allowed.
  3. Limiter strap allowed but must maintain two inches of travel.
  4. Front suspension shocks must be welded body hydraulic shocks. Must be OEM for the model. OEM diameter and linkage must be maintained.

TORSION BARS


TRACK SUSPENSION

  1. The complete suspension must be used as furnished and filed by the manufacture. There will be no suspension options permitted in Stock classes. **Travel may be limited with straps or chains but must maintain two inches of usable travel.
  2. No gas shocks allowed. Must use hydraulic welded body shocks.
  3. Front rail/skid frame shock may be defeated but must be in place.

    4. SUSPENSION WHEELS

  4. OEM for the model suspension wheels, marginal snow wheels may be added or removed.
  5. OEM for the model rear idler wheels may be added. Aftermarket replacements allowed. OEM style bearings only. No exotic metal or ceramic bearings allowed. Slide rail lubrication systems allowed.

TRACK

  1. No “R” rated tracks allowed.
  2. Any OEM track of original dimensions may be used. Dimensions are defined as track length, width, and drive specified dimension. Example wide X121” Long with 2.52 Drive Pitch. No pitch changes allowed. Track height must be no greater than 1” (one inch) lug height. Re-clipping/repair is allowed.
  3. No hooker studs.

    4. FRAME and BODY

  4. Must have stock hood and belly pan.
  5. Headlight may be removed but the hole must but covered if removed. Headlight retention is encouraged as it is a stock-based class. Frame must not be altered or bracing added. No drilling of holes in chassis or frame to move suspension.
  6. No chassis or suspension component reinforcement allowed.

    7. CLUTCH

  7. Primary and secondary clutch must match year, make and model of snowmobile.

    8. SKIS

  8. Extruded aluminum skis allowed. Maximum of 6-inch carbides.

    9. EXHAUST

  9. Must retain OEM exhaust system. No altering allowed. This includes removal of sound deadening material.

    10. HANDLEBAR

  10. Handlebar may be replaced, including extensions, to fit the driver. Handlebar column must remain in its original position and centered to the chassis.

    11. HANDLEBAR

  11. Sled weight must be within 20 pounds of original filed weight for the model. The 20-pound max variance is allowed due to the allowed removal of the air box and sound deadening foam inside the engine compartment. Filed weights for the models competing in this class are on record.

CLASS SPECIFIC RULES

  1. No use of titanium or carbon fiber components.
  2. No use of F500 suspension components in either the front or rear suspensions.
  3. No use of F-500 specialized suspension components in either front or rear suspensions. No Hooper/Wahl or other aftermarket F-500 legal kits allowed.
  4. Offset of any chassis is limited 1⁄2 “ (.500 inch) center to center.

JUNIOR
JUNIOR (ages 10-13)
Trophies awarded at each race.
  1. Entry fee is $10.00.
  2. Parent must sign the necessary release forms and driver must be a member.
  3. Single cylinder, fan cooled stock sled.
  4. Must follow Safety, Stock and General Rules.

    5. JUNIOR (ages 14-16)
    Trophies awarded at each race.
  5. Entry fee is $10.00.
  6. Parent must sign the necessary release forms and driver must be a member.
  7. Single cylinder, fan cooled sled or small fan twin.
  8. Must follow Safety, Stock and General Rules.
  9. CAN NOT move up to any adult class until the age of 16. NO EXCEPTIONS.

BOMBER CLASS ($15.00 entry fee)
Trophies awarded at each race.
  1. 1974 and older, Single cylinder fan cooled up to 400cc.
  2. HR, HD, and up to 38mm Micuni carbs.
  3. Stock engine and chassis. No overbore. No engine mods.
  4. Mid mount and front mounted engine allowed.
  5. Stock primary clutch or duster/power block.
  6. Steel skis.
  7. No reed valve engines.

RELIC CLASS ($25.00 entry fee)
Trophies awarded at each race.
  1. Must follow all Safety, General and Stock Rules.
  2. Any can style exhaust with baffles.
  3. 1974 and older, fan cooled, single cylinder only.
  4. Piston port only, no reed valves.
  5. Must have stock appearing cowl.
  6. No chassis modification of any kind.

SINGLE CYLINDER
SINGLE CYLINDER FAN COOLED STOCK ($25.00 entry fee)
Trophies awarded at each race.
  1. Must follow all Safety, General and Stock Rules.
  2. Any can style exhaust with baffles.
  3. 1985 or older, fan cooled, single cylinder only.
  4. Piston port only, no reed valves.
  5. Must have stock appearing cowl.
  6. No chassis modification of any kind.
  7. Reed or piston port

SINGLE CYLINDER FAN COOLED MOD ($25.00 entry fee)
Trophies awarded at each race.
  1. Sled and driver must meet and follow all Safety and General Rules.
  2. 1985 and older, fan cooled, single cylinder only.
  3. Sled can be front or mid mount engine.
  4. Engine must match brand.
  5. Any type carburetor.
  6. Any type exhaust.
  7. Any type clutch.
  8. Must have stock appearing cowl.
  9. Must use stock cylinder. Any modification allowed.
  10. Any ignition, reeds allowed if the engine comes with reeds
  11. Any suspension and chassis mods are allowed.
  12. Maximum ski width 45" (outside to outside).

300 AIR COOLED STOCK ($25.00 entry fee)
Trophies awarded at each race.
  1. Must follow all Stock Rules.
  2. Sled and driver must meet and follow all Safety and General Rules.
  3. 1985 or older, free air 0 - 300cc.
  4. Fan or free air.

340 FAN COOLED STOCK ($25.00 entry fee)
  1. Sled and driver must meet and follow all Safety and General Rules.
  2. Must follow all Stock Rules.
  3. 1985 and older 0 - 340cc fan cooled.
  4. All fan covers and fans must be in place and working.

340 FREE AIR / liquid STOCK combo ($25.00 entry fee)
  1. Must follow all Stock Rules.
  2. Sled and driver must meet and follow all Safety and General Rules.
  3. 1985 or older, leaf spring, 0 - 340cc free air.

340 SUPER MOD IFS ($25.00 entry fee)
  1. Sled and driver must meet and follow all Safety and General Rules.
  2. Any year up to 340cc IFS.
  3. Any chassis or suspension.
  4. Single track only.

340 LIQUID MOD SOLID FRONT END LEAF SPRING ONLY ($25.00 entry fee)
  1. Must have 5 or more sleds.
  2. 250 CC IFS sleds allowed.

440's
440 FAN COOLED STOCK ($25.00 entry fee)
  1. Must meet and follow all Stock Class Rules.
  2. Sled and driver must meet and follow all Safety and General Rules.
  3. 1985 or older, factory leaf spring, 0 - 440 fan cooled.

440 FREE AIR STOCK ($30.00 entry fee)
  1. Must meet and follow all Stock Class rules.
  2. Sled and driver must meet and follow all Safety and General Rules.
  3. 1985 or older, leaf spring, 0 - 400 free air.

440 Liquid Stock ($30.00)
  1. Sled and driver must meet and follow all Safety and General Rules.
  2. 1985 or older chassis, factory leaf spring.
  3. 1985 or older 0 - 440cc air cooled engine.
  4. Any type carb, clutch, suspension, ignition or exhaust.
  5. Must use stock cylinder and modifications allowed.
  6. Engine must match brand.
  7. Chassis modifications are not allowed.
  8. Maximum width 45".

440 FREE AIR SUPER MOD - ADIRONDACK CUP CLASS ($30.00)
  1. Sled and driver must meet and follow all Safety Rules.
  2. 1985 or older factory leaf spring.
  3. 1985 or older 440cc air cooled engine.
  4. Any type carb, clutch, suspension, ignition or exhaust.
  5. Must use stock cylinder.
  6. Engine must match brand.
  7. Any Chassis or Engine modifications are allowed.
  8. Maximum width 45".

44O LIQUID MOD ($30.00 entry fee)
  1. Sled and driver must meet and follow all Safety and General Rules.
  2. 1985 or older, factory leaf spring, 0 - 440cc liquid cooled or independent.
  3. Any type carb, clutch, suspension, ignition or exhaust.
  4. Must use stock cylinder and modifications allowed.
  5. Engine must match brand.
  6. Chassis mods are allowed. Maximum width 45 inches.
  7. Maximum width 45".

440 SUPER MOD IFS($30.00 entry fee)
  1. Sled and driver must meet and follow all Safety and General Rules.
  2. Any year 0 - 440cc IFS single or twin track.

OPEN 600 ($30.00 entry fee)
  1. Sled and driver must meet and follow all Safety and General Rules.
  2. Any year 0 - 600cc.
  3. Any modifications.
  4. 45" total ski width.
  5. Single or twin track.
  6. Outlaw sleds allowed.

COMBO CLASS ($30.00 entry fee)
  1. Sled and driver must meet and follow all Safety and General Rules.
  2. 0 - 340cc IFS single track.
  3. 1985 or older, 0 - 440cc solid front end, single track.
  4. In 440cc, engine must match chassis.
  5. Sprint sleds and F500 allowed.

SENIORS CLASS -(DRIVER 50+, $30.00 entry fee)
  1. Must follow stock class rules PLUS.
  2. 1990 or older 440 air cooled stock or 340 liquid stock.
  3. Engine must match chassis brand.
  4. Any stock exhaust.
  5. No Chassis mods allowed example: hood, suspension, track, skis.
  6. Max 45" ski width.
  7. Any type carb, clutches, ign., or single exhaust

SAFETY RULES FOR ALL CLASSES
  1. All sleds must pass a tech inspection before racing.
  2. All sleds must have:
    1. Working brake
    2. Working tether switch with tether attached to the driver
    3. Chain guard
    4. Cowl over engine compartment f. Rear flap no more than 2" above the ground
  3. Tether must be attached to the driver or pit member whenever the sled is running.
  4. All stands must be properly guarded.
  5. DO NOT over rev sled on a stand. (VERY DANGEROUS)
  6. Driver must wear a snowmobile helmet with at least 4" of bright tape.
  7. Shin guards must be worn on at least one leg.
  8. Safety jackets are a MUST for every driver. No plastic motocross chest protectors are allowed.
  9. Driver must wear a protective jacket and pants.
  10. A neck restraint is recommended.
  11. Alcoholic or drugs are NOT allowed in the PIT AREA. You will be asked to leave.
  12. No inappropriate behavior or language in the PIT AREA.
  13. No racing in PIT AREA.
  14. The Race Director has overall control over the event.
  15. All drivers must obey the pit marshal, flagman and corner men.
  16. The flagman is in control of the track during hot laps and the race.
  17. Race Committee will assist the Race Director in solving disputes during or after the race.
  18. Flags used during the race :
    1. Green: Go race
    2. Yellow: Race with caution
    3. Red: Stop the race
    4. White: One lap to go
    5. Checkered: End of race
    6. Black: Drop out of race
  19. All sleds must complete the first lap or the race will be restarted.
  20. In case of a Red flag, line up in order at the time of the red flag.
  21. Two lap shoot out for the last lap red flag.
  22. All snowmobiles in all classes - The rear tunnel must be enclosed with steel or aluminum comparable in strength to the tunnel material. The tunnel enclosure is required to reduce the possibility of skis and driver's extremities entering the tunnel area. The shaded area (see illustration) must be enclosed. The enclosure shall cover the rear and both sides and extend forward to the rear suspension mounting bolt. The bottom of the enclosure shall be no higher than one (1) inch above the center of the rear axle (with the driver in place). The rear of the enclosure shall be no further than 2.5 inches from the rear of the track. The tunnel enclosure must be securely welded, bolted or riveted to the tunnel.
  23. Must have a non-blinking tail light. Minimum 4 square inches.
  24. No modular helmets.
  25. All helmets must be Snell approved or be equivalent.
  26. Protective boots or shoes. No sneakers.


INTENT AND SPIRIT OF THE CLASS


This class is designed to be an affordable, fun, class of competition. It can be a starting point for a young driver or a level of competition for older drivers who no longer wish to compete in hi-level classes.


The class rules for this class are froze for four years. The next allowable rule changes will be proposed in spring of 2024 to be adopted in the 2025 season. This assures the ability to build a sled that has longevity and does not require costly annual upgrades. This is a factory stock produced snowmobile. The way it was produced is the way it must be ran, the only exceptions are the specific rules noted in the above text indicated by this symbol (**). [15 items]


If it is not listed, it does not mean you can alter it.


If you desire a class with more liberal rules, or the ability to be creative in construction, please participate in any of the other USSA oval classes available.


The only revisions to this class for the next four years will be safety related changes, and only if required by recorded incidents or failures.


F500 and sportsman 500 follow Isr rules please refer to their website for build specifications and clarification. F340 follows F500 rules using a 2002 or older indy 340, 340 sport or 340 lite.