FORMULA 500 CLASS
FORMULA 500 ($30.00 entry fee)
Trophies awarded at each race.
IN THE FORMULA 500, NO CHANGE OR MODIFICATION CAN BE DONE TO THE STOCK QUALIIFIED SNOWMOBILE UNLESS SPECIFICALLY ALLOWED BY THESE RULES. IF THESE RULES DO NOT SPECIFICALLY ALLOW A CHANGE OR MODIFICATION, IT MUST BE ASSUMED THAT THE CHANGE OR MODIFICATION IS NOT ALLOWED. THESE SLEDS WILL BE BUILT TO RESEMBLE A SPRINT OR CHAMP SNOWMOBILE OF ANY OF THE CURRENT BRANDS.
1. Snowmobile must comply with the General Rules and Regulations Section.
2. The sled must originate from 1989 - 1992 Polaris Indy 500 carb model.
3. The brand of hood, engine and logo need not match.
4. Removal of any material from total machine by means of heat, acid, drilling, grinding, sand blasting, peening, substitution or total elimination will not be allowed unless otherwise specified in this section.
5. Minimum weight is 400 pounds.
6. Maximum overall width of sled is 45 inches
1. No component of the engine may be altered, changed or enlarged from the engine manufacturer's original stock specifications, nor any additional components be added to the engine. No engine kits allowed.
2. Blueprinting is not 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. No changes in engine dimensions can be made by gasket adjustments. Gaskets may be trimmed but must remain OEM and OEM thickness.(KIMPEX gasket set part # 09-712185A & SPI gasket set part #G5005 may be used).
4. Maximum cylinder overbore for wear or cylinder repair cannot exceed .020 inches (1/2mm)
5. OEM for the model and Kimpex or SPI for the model pistons, rings and engine gaskets are allowed for replacement. The following replacement pistons are allowed:
(Pistons KIMPEX standard 09-711)
(Pistons KIMPEX .01009-711-01)
(Pistons KIMPEX .02009-711-02)
(Pistons SPI standard 9712PS)
(Pistons SPI .0109712P1)
(Pistons SPI .0209712P2)
6. Replacing OEM carburetor slide valve and replacement jet components without modification will be allowed in Formula 500. No modifications to carb body allowed.
7. No additional fuel pumps may be added.
8. Air box and oil injection system may be removed.
9. Thermostat may be removed.
10. Cooling system must remain completely stock and in the OEM location.
11. The spark plugs, spark plug wires and connectors do not have to be OEM.
12. The exhaust system must be OEM for the model and mounted in the OEM location for the model. Welded on after muffler and internal stinger pipe may be removed and replaced with any size stinger. The exhaust system must be functionally silenced. The ball socket on exhaust chamber may be repaired or replaced, but MUST maintain original tuned length and inside diameter. NO OTHER CHANGES ALLOWED.
13. No changes or repairs allowed to "Y" pipe.
14. Engine must remain in stock location and must use stock engine plate and mounts. Torque limiters allowed.
1. Drive clutch must be P-85 Polaris
2. Any commercially available drive and driven clutches and internal components allowed.
3. Clutches and components may be modified. (The use of a Quick Change 85 Polaris drive clutch is not allowed)
4. Chain case and track shaft must remain stock and in stock location; no modifications or lightening allowed. Chain and sprocket ratio may be changed. Belt drive system is not allowed.
5. Jackshaft with a key may be replaced with a jackshaft of the same model and material with splines.
6. Any OEM appearing, solid, and of like material (steel) replacement jackshaft may be used.
7. Any 8” (inch) OEM steel brake disc and hub may be used. The disc may not be modified in the pad contact area. No wave disc allowed, No aluminum or titanium hubs allowed.
8. Any commercially available brake master cylinder will be allowed.
9. Any OEM Polaris brake caliper will be allowed. Caliper must attach to the existing chain case without modification to the chain case, Caliper may be modified to fit chain case.
10. Brake cooling duct, inside the hood, is allowed.
SKI SUSPENSION & STEERING
1. Ski suspension and steering must be OEM for the model unless other wise specified.
2. Radius rods and tie rods may be replaced or modified.
3. Maximum total offset allowed is 1" inch measured from the center of the bulkhead. Example: 23 inches from the center of the bulkhead to the outside right ski and 22" inches from the center of bulkhead to the outside left ski = 45 inches outside ski distance with 1 inch total offset.
4. Must use all original suspension mounting points on chassis and struts.
5. May use any springs or spring adjusters. Titanium springs are not allowed.
6. POLARIS part #7041144 is the only ski shock allowed.Shock absorbers must be OEM for the model or ISR designated replacements. KIMPEX part # 08-113 is the only replacement ski shock allowed.
7. Sway bars may be replaced but must fit in stock location thru bulkhead.
8. Limiter strap allowed, but must maintain two and one half (2.5) inches of usable downward travel with driver seated. Travel measured at the front bumper.
9. Suspension components may be reinforced, but no geometry changes are allowed except chamber.
10. Steering column and handlebars may be relocated and/or replaced. Extensions may be added to suit the driver. The lower end of the steering column must be secured with a minimum of 4 bolts. One of the 4 bolts must be in one of the OEM mounting holes. The handlebar and column material must be of same as the OEM material with the same wall thickness (or greater) and tubing outside diameter as the OEM components. The use of a universal joint is not allowed
11. Throttle lever may be replaced, but must be thumb operated with a direct mechanically operated mechanism on rear side of the right handle bar.
SKIS & SKI RUNNER
1. OEM (for the brand) or aftermarket skis allowed. Must conform to General Competition Rules. Ski mount on spindle may be narrowed to allow ski mounting.
2. Minimum flat length of ski bottom is 14 inches. Minimum ski width is 3 1/4 inches.
3. Reinforcement is allowed on the top of the ski board only.
4. Reinforcement carbide length is 6 inches per ski. May not use more than a 6 inch long sharp edge of any kind per ski.
1. Complete track suspension and components MUST be OEM stock for the model unless otherwise specified.
2. Track suspension must maintain a minimum of 2 inches of usable, vertical travel with the driver seated.
3. May drill new holes in tunnel or rail to change mounting locations. May not drill excessive amount of holes for lightening.
4. May modify or replace springs. Titanium springs are not allowed.
5. Shock absorbers must be OEM for the model or ISR designated replacements. (Polaris part # 7041142 is the only OEM front shock of the rear suspension allowed. KIMPEX part # 04-271 is the only replacement front shock of the rear suspension allowed. POLARIS part # 7041250 is the only OEM rear shock of the rear suspension allowed. KIMPEX part # 04-235 is the only replacement rear shock of the rear suspension allowed )
6. May remove front shock.
7. May relocate rear shock.
8. May change or add limiters to front and rear of track suspension. No remote limiter adjusters allowed.
9. May add or subtract marginal snow wheels and their mounts.
10. May add slide lubrication system.
TRACK & TRACTION
1. Any commercially available rubber track 121 inches x 15 inches is allowed. Minimum track lug height is .50 inch.
2. The track must be used as produced by the molder of the track. No cutting or other modifications allowed.
3. No weld on hooker's plates.
4. No studs allowed directly under rails.
5. Traction products must conform to Oval Sprint requirements.
FRAME & BODY
1. Must use 1989 - 1992 Polaris Indy 500.
2. Chassis may be reinforced.
3. May alter or replace hood, windshield, belly pan, seat, fuel tank and foot stirrups.
4. May remove bumpers, dash panels, oil tank, lights and wiring.
IGNITION & ELECTRICAL
1. Ignition system MUST be OEM stock for this engine, no modifications allowed. May not lighten flywheel.
2. Instruments gauges and headlight may be removed.
3. Data acquisition and data acquisition systems not allowed. (This includes memory tach)
4. A DOT approved LED taillight must be illuminated whenever the snowmobile is on the racing surface, whether the engine is running or not.
5. Instruments, gauges and headlight may be altered, removed or replaced.
6. Spark plugs, spark plug wires and connectors do not have to be OEM.
Must run non oxygenated fuel