MIRA
500 LIMITED
The limited 500 class is a class designed to offer the performance potential of a true racing class, with control factors in place to attempt to maintain affordability, longevity of the chassis and power plant and true continuity.
The 500 limited class is open to 440/ 500liq. And 600 fan stock class sleds in stock trim as produced from the manufacturer for 09. This will then be reviewed on an annual basis.
1. Chassis shall be OPEN SPRINT style chassis, either production or hand built.
2. The sled must meet all applicable safety and general criteria in this section and in the general rules and regulations of the ISR rulebook.
3. Engine, Chassis, and Hood need not match.
4. The minimum weight shall be 350 lbs
5. The maximum width is 45 in overall.
These rules are in force for 5 years from this date 5/8/07
ENGINE
1. The engine must be from a stock qualified fan or liquid cooled model with a single exhaust pipe and a maximum displacement of 500cc liquid and 600cc air. No other modifications allowed except those listed below.
2. Engine must conform to the 15 year rule.
3. Air box / air induction piping may be removed.
4. OEM factory WYE pipe for the engine must be used.
5. OEM exhaust expansion chamber must be used. Allowable modifications to the expansion chamber are as follows:
a. Exhaust stinger may be modified or changed.
b. The expansion chamber proper must maintained with out modifications.
c. Exhaust must be functionally silenced.
d. Chassis design must accommodate the exhaust system without change.
6. Oil injection pump may be removed.
7. OEM production carburetors or OEM EFI system must be used without modification except filed tuning components.
8. OEM cooling concept must be maintained.
9. Engine mounting plates and configuration may be modified or changed.
No additional modifications to the as production engine allowed.
IGNITION AND ELECTRICAL
1. OEM production ignition system must be maintained
2. Operating, highly visible taillight must be functional whenever the engine is running.
DRIVE
1. Any commercially available CVT type drive and or driven clutch may be used
2. Diamond drive/Arctic Cat systems are legal, no light weight components allowed.
3. No titanium jackshafts, axel shafts, or any other rotating except clutch springs allowed.
4. A production chain case / gear case from any OEM may be used, but must be a stock production case.
5. Chain case cover need not be used.
6. Chain case may be modified to except non OEM brake caliper.
7. Clutch guard cover must conform to the ISR safety specification as a modified sled.
SKI SUSPENSION AND STEERING
1. Minimum of 2 inches of useable vertical travel required must be maintained during operation.
2. Shock absorbers must be FOX gas charged hydraulic shocks. Shock may be revalveable..
3. No external adjusters except “clickers” adjusters allowed.
4. No remote reservoirs allowed on ski or suspension shocks.
5. No air shocks/floats allowed.
6. No electronically monitored or controlled shocks allowed.
Any shock determined to not be in the spirit of the rules must be removed at the tech director’s decision.
SKI AND SKI RUNNERS
1. Carbides (one cutting edge) plus one additional edge may extend no more than 5/8 of an inch from the lowest surface of the ski. Only one (1) cutting edge per ski is permitted on independent front suspension sleds. Any ski edge over ˝ inch turndown constitutes a legal keel cutting edge. The ski runner, carbide edge or wear bar may be altered to a single plane angle of not less than 60 degrees inside included edge.
TRACK SUSPENSION
1. Shock absorbers must be FOX gas charged revalveable hydraulic shocks only.
2. No external adjusters except “CLICKER” adjusters.
3. No remote reservoirs allowed.
4. No air shocks/”Floats” allowed.
5. No electronically monitored or controlled shocks allowed.
6. Maximum allowable idler wheel diameter is 8 inches
7. No titanium shafts allowed anywhere in the suspension.
8. Suspension must be a production based slide rail.
TRACK AND TRACTION
1. Track must be “R” rated commercially available one piece molded rubber track.
2. Minimum length is 116 inches
3. Minimum width is 15 inches
4. Any track wear clip combination allowed.
FRAME AND BODY
1. A rear tunnel enclosure is mandatory
2. Hood must be OEM production or OEM replica. Color and paint schemes are open to the builders discretion.
3. No carbon fiber is allowed anywhere on the race sled.
4. Belly pan / lower body is at builders discretion.
BRAKES
1. Commercially available hydraulic brakes only
2. No light weight aluminum discs
3. Brakes may be mounted on jackshaft or drive axle
4. Liquid cooled brakes allowed.
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