600 Limited Regional

 

GENERAL RULES
NOTICE: These rules are in force for 5 years from 1 Jun 09 to 1 Jun 14. Carburation/EFI may be reviewed at any time.
Chassis shall be an Open Sprint style   chassis, either production or hand built.
The snowmobile must meet all applicable safety and general criteria in this section and in the General Rules and Regulations section of the current ISR Yearbook.

  1. Engine, Chassis, and Hood need not match.
  2. Minimum weight is 350 pounds.
  3. Maximum width is 45 inches overall.
  4. By entering the class, the competitor agrees that any chassis or engine components which to not comply to rules may be confiscated by the sanctioning body.

ENGINE

  1. The engine must be from a stock qualified  liquid cooled model with a single exhaust pipe and a maximum displacement of 600 cc. Allowed modifications to the engine are listed below.  No other modifications are allowed.
  2. Engine must conform to the 15-year rule.
  3. Air Box/air induction piping may be removed.
  4. OEM factory  wye “Y” pipe for the engine must be used.
  5. OEM Exhaust expansion chamber must be used. Allowable modifications to the expansion chamber are as follows:
    1. After muffler/silencer canister may be removed.
    2. Exhaust stinger may be modified or changed.
    3. The expansion chamber proper must be maintained with no modifications. This is subject to the Technical Director’s decision and may not be appealed.
    4.  Exhaust must be functionally silenced.
    5.  Chassis design must accommodate the exhaust system, no changes to the exhaust system for chassis fit are allowed.

6. Oil injection pump may be removed.
7. OEM production carburetors for the model and year or OEM EFI system for the model and year  must be used with no modifications except filed tuning components.
8. The OEM engine-cooling concept must be maintained.
9. Engine mounting plates and configuration may be modified or changed.
10. No additional modifications to the stock (as produced) engine are allowed.
DRIVE
1. Any commercially available CVT type drive and or driven clutch system may be used.
2. No lightweight components allowed.
3. No titanium jackshafts, axle shafts, or    any other rotating component except clutch springs are allowed.
4. A chaincase/gearcase from any OEM stock qualified model may be used.  (Diamond drive/Arctic Cat systems are allowed.) Chain case original origin must be declared during technical inspection if requested by technical inspector. Failure to declare will result in disqualification without appeal privileges.  Chaincase may be modified to accept non OEM brake caliper.
5. Clutch guard must conform to General Oval rules for modified snowmobiles.
6. Commercially available hydraulic brakes only. Stock OEM brake discs only.
7. No lightweight brake discs.
8. No wave brake discs.
9. Brake discs may be mounted on jackshaft or front drive axle.
10. Liquid cooled brakes allowed.

SKI SUSPENSION AND STEERING

1.  Minimum of 2 inches of useable vertical travel required and must be maintained during operation.
2. Shock absorbers must be Fox gas charged hydraulic shocks. Shocks may be revalveable.
3. No external adjusters except “clicker” adjusters allowed. No remote reservoirs shocks allowed.
4. No air spring/ “float” shocks allowed.
5. No electronically monitored or controlled shocks allowed.
6 .Any shock determined to not be in “the spirit of the rule” must be removed and replaced with a conforming shock absorber. Technical inspector’s determination is final.

skis & ski runners

1. Skis and ski runners must conform to General Rules for Oval Sprint Racing.
TRACK SUSPENSION
2. Shock absorbers must be Fox gas charged hydraulic shocks. Shocks may be revalveable.
3. No external adjusters except “clicker” adjusters allowed. No remote reservoirs allowed.
4. No air spring/ “float” shocks allowed.
5. No electronically monitored or controlled shocks allowed.
6. Any shock determined to not be in the “spirit of the rule” must be removed and replaced with a conforming shock absorber. The technical inspector’s determination is final.
7. Maximum diameter eight (8) inch rear idler wheels.
8 . No titanium shafts/ titanium allowed anywhere in the suspension.
9. Suspension must use a production based slide rail. Slide rail origin must be declared when requested by the technical inspector. Failure to declare origin will result in disqualification without appeal privileges.
TRACK and traction
1. Track must be “R” rated commercially available one-piece molded rubber track.
2.  Minimum length is 116 inches. Maximum is 121 inches.
3.  Minimum width is 15 inches.
4.  Any track wear clip combination is legal.

FRAME AND BODY

  1. A rear tunnel enclosure is mandatory.
  2. Hood must be an OEM production or OEM replica. Hood must not be modified in any manner that prevents it from being recognized as a current production model snowmobile.
  3. 3.  No carbon fiber is allowed anywhere on the snowmobile.
  4. Any belly pan/lower body allowed.

ignition & electrical

  1. Ignition system must be OEM for the model engine.
  2. An approved LED taillight must be illuminated whenever the snowmobile is on the racing surface, whether the engine is running or not.

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