MIDWEST INTERNATIONAL RACING ASSOCIATION

1. Enduro events are run on ice oval tracks. The recommended minimum track length is 1/2 mile.

2. The length of each race is at the discretion of the sanctioning body. Enduro race length can range from 10 miles to 500 miles.

3. In conjunction with Enduro races, sprint oval races may be part of the event.

4. Classes are established as indicated below:

Pro Mod 600 Enduro (minimum 100 laps)

Semi-Pro Super Mod Enduro

Junior Enduro

Pure Stock 600

Pro Open 600

Pro Champ

Semi-Pro Pure Stock 600

Semi-Pro Open 600

Semi-Pro Champ

Limited 500

Limited 600

Formula 500

Junior I, II, III

1. Can be any snowmobile Enduro racing class or event that does not fall under any of the specific circuits or classes, but meets established safety standards, applicable laws and/or approved insurance coverage.

2. All special sanctions and specialty classes must be approved in writing by ISR before competition.

1. Refueling system will be subject to inspection and must be approved by the Tech/Safety Director. Refueling system must be gravity fed or operated by a hand pump. No electric pumps or other pressurized systems allowed.

2. All teams assigned to a pit area shall have at least one fully charged five-pound dry chemical fire extinguisher accessible (this applies to the trials and race days).

3. Dumping or improper disposal of fluids is not allowed.

4. No loose animals allowed at race site.

5. Speeding in the pit and paddock areas will subject the participant to disqualification, fine, and/or loss of laps.

6. Radio communication allowed between crew and driver.

7. A driver must be 18 years of age on the day of qualification trials for the race.

8. Each machine entered in the race must have a team of no less than two (2) and no more than five (5) drivers.

9. All machines entered in the race will pass through a technical inspection two (2) hours prior to the start of the race. The exact time will be announced at the drivers meeting.

10. A pace machine will be used for the start of the race and during the race when safety conditions dictate. Absolutely no passing of the pace sled is allowed. If violated a mandatory penalty will be implied.

11. A race may be declared complete when one machine has completed one lap more than one half the total distance of the event. This is left to the discretion of the race director.

12. A participant is any person taking part in any event sanctioned by or affiliated with International Snowmobile Racing, Inc. in any form, including but not restricted to drivers, sled owners, mechanics, crew members, sponsors, track officials, pit area personnel, manufacturers and press representatives. All such persons shall be considered public figures that have by their own choice become involved in snowmobile racing events, with the full understanding that he or she must abide by the rules and regulations established and published by ISR. All participants are considered responsible for their personnel conduct.

1. The condition of a snowmobile is the responsibility of the team.

2. A team may be disciplined if a team's snowmobile is modified so as to defraud the officials or other competitors.

3. All aspects of modification are contingent upon inspection by the technical director and his staff. The technical director may remove any snowmobile from competition that does not meet the requirements of the class. In event of an accident, the technical director may at his/her sole discretion, rule said machine(s) unsafe to continue to participate in the event. These machines must be fully inspected by the technical director prior to returning to the event competition. Violation of these rules may result in expulsion from the event.

1. In order to be eligible for competition, a four-stroke powered snowmobile must be classified through the ISR four- stroke classification procedure. Currently a naturally aspirated 1050cc inline 3 cylinder only is allowed.

1. (Mandatory in all classes except Stock where it is recommended.) The clutch cover must be separate of cowl configuration and cover clutches down to center of clutch bolt or below. Must be .060 inch, 6061T6 aluminum or equivalent steel material and be covered with 6 inch wide belting. Snowmobile with removable side panels may bolt clutch cover to side panel to meet this requirement.

3. Ski tip (not including the loop) must be turned up a minimum of 1.5 inch from the bottom of the ski (not including the keel(s) or ski runner).

1. Unless disallowed by local environmental laws, slide rail lubrication allowed. Must use non-toxic, biodegradable lubricant.

2. Stud plates welded onto track clips must be no longer or wider than track clip. Only one plate allowed per track clip. Rubber between ends of track clip may be trimmed to allow welding on stud plate.

1. Orange or fluorescent orange color cannot be used on any snowmobile.

1. Maximum tether cord length is four (4) feet (measured with the cord fully extended).

2. An approved LED taillight must be illuminated whenever the snowmobile is on the racing surface, whether the engine is running or not.

NOTICE: See Oval Sprint Stock class rules.

NOTICE: See Oval Sprint Champ class rules

This is a modified class but the chassis and engine are required to originate from a stock qualified production snowmobile.

1. Snowmobile must comply with the GENERAL RULES AND REGULATIONS section.

2. Factory options are not allowed unless otherwise specified.

3. Minimum weights are as follows:

a. Twin Cylinder up to 500 cc minimum displacement is 400 pounds.

b. Twin cylinder engines up above 500 cc displacement is 440 pounds.

c. All three cylinder engines, 440 pounds. The above weights include chainlube and engine coolant.

4. No engine fuel other than pump gasoline and all AV (aviation) gas will be allowed. No special additives will be allowed. Dry gas (Deicer) will be allowed up to three (3%) of the fuel volume. Bulk fuel tanks can be used and must conform to applicable safety and fire prevention rules. Local Fire Marshall rules and regulations will prevail concerning fuel storage and handling.

1. All engines must originate from a stock qualified model. Interchange of production based engines within the brand is allowed.

2. Engine must originate with a displacement of 600 cc or less. (2 cycle) Cylinders may not be sleeved down to reach 600cc's. Maximum cylinder overbore for wear or cylinder repair cannot exceed .020 inch (1/2 mm)

3. There will be no interchanging of cylinders, crankcase or crankshaft between brands. Engine must retain original number of cylinders. Internal engine port concept may be modified (extra exhaust, intake, transfer ports or valves may be added or eliminated. Aftermarket cylinder heads allowed.

4. Engine must be naturally aspirated (no supercharging or turbo charging). Original intake concept can only be changed by adding reed valves to the cylinders or crankcase.

5. No special casting procedures/ castings allowed.

6. All crankcases must have originated from a 600 cc or less displacement stock production engine.

7. The engine must retain original cooling concept. Additional cooling mediums may be added (water cooled sleds may add radiators, or additional extrusions within the confines of the snowmobile).

8. The engine may not be move sideways in the chassis. Engine may be raised or lowered.

9. Any carburetor allowed. Fuel injection not allowed unless OEM for the model.

10. No air induction devises (ram air) will be allowed in the induction system.

11. All snowmobiles are required to have a functionally silenced exhaust system. Exhaust system must not protrude more than three (3) inches outside the hood/chassis.

1. Primary and secondary clutches may be replaced with any properly filed clutch. Clutch and component must have originated from a commercially available snowmobile clutch. No machining on the clutches to accommodate springs, weights, or helixes allowed.

2. Chain case components may be altered, but must remain in OEM location.

3. Jackshaft and drive axle must remain in OEM location.

4. Track drive axle, track drive sprockets and non-driving wheels may be replaced. No material substitution allowed. No modification to chassis or drive parts allowed to accomplish axle and/or sprocket replacement.

5. Brake components may be replaced. Brake components must be commercially available and must not be modified. Liquid cooled systems allowed. Brake disk must be OEM (for the model) material and must be at least as large in diameter and as thick as OEM for the model disk. Existing vents may be used to direct cooling to the braking mechanism.

6. Drive belts do not have to be OEM.

1. Trailing arms must be OEM length. Mounting location must be OEM for the chassis.

2. Handlebar column must remain in original position in lower chassis mounting position. The steering column upper mount point may be relocated to suit the driver.

3. Handlebars may be altered to fit the driver.

4. Ski suspension and steering must be OEM for the model unless otherwise specified.

5. Maximum ski stance is 45 inches measured between the ski runner cutting edges. Ski runner cutting edges must be centered on the ski and on the spindle.

6. The ski stance distance must be centered on the center of the tunnel.

7. OEM for the model front suspension concept must be maintained (i.e. trailing arm or "A" arm).

8. Suspension components including arms, spindles, radius rods, rod end bearings, shock absorbers, springs and sway bars may be altered or replaced. Structural integrity must be maintained.

9. Sway bars may be removed.

10. Limiter strap allowed, but must maintain two (2) inches of usable downward travel with the driver seated. Travel measured at the front bumper.

11. Handlebars may be replaced, including extensions, to fit the driver. All ends must be plugged (see diagram in GENERAL COMP. SECTION). The handlebar must be of the same material with the same wall thickness (or greater) and tubing outside diameter.

12. Throttle lever may be replaced but must be thumb operated with a direct mechanical operated mechanism on rear side of right handlebar.

1. Any seventeen (17) inch or longer ski may be used. Must conform to General Competition Rules. No aluminum skis allowed.

2. Minimum ski width is 3 1/4 inches.

3. The ski runner or wear bar may be altered to an angle of not less than sixty (60) degrees inside included angle. Carbide must be centered on the ski board. The ski runner must follow the contour of the ski and be no longer than the ski.

1. Track suspension may be altered, relocated or replaced. Structural integrity must be maintained.

2. Suspension must maintain a minimum of 2 inches of useable, vertical travel with the driver seated.

3. The track suspension and track must be centered in the tunnel with a maximum of 1.250 inches between the edge of the track and the side of the tunnel.

1. Any commercially available one-piece molded rubber track allowed. It must be race-rated by the molder of the track. No cleated tracks allowed. Track must fit within the confines of the OEM for the model tunnel without modification to track, drive system or tunnel (track suspension relocation holes may be added to tunnel).

2. The track must be used as produced by the molder of the track. No cutting or other modifications allowed.

4. Stud backing plate; cannot be over two and one quarter (2 1/4) inches in width and length.

1. The rear tunnel opening must be enclosed with a material of comparable strength to the tunnel material. The tunnel covering is required to reduce skis and drivers extremities from entering tunnel area. Both sides and rear tunnel opening must be enclosed. Enclosure will begin at rear suspension mounting bolt, continue past the rear idler wheel (approximately three (3) inches above rear mounting bolt with driver on snowmobile) and cover the rear tunnel opening (within 2 1/2 inches of the rear of the track) and continue on to the rear suspension mounting bolt on the opposite side of the tunnel. This does not supecede the snow flap rule.

2. Windshield must be OEM for the model or equal an OEM windshield in dimensions and must be mounted in OEM location as filed. Six inches of the left side of the windshield may be flared to allow for handlebar movement. Minimum stock windshield height must be maintained. Must have, safety edging. Windshield must be intact at the start of the race.

3. Only one fuel tank allowed. Tank must be OEM approved or a commercially available aftermarket tank meeting or exceeding OEM standards. Maximum fuel tank capacity is 13.0 U.S. gallons. Fuel tanks may be changed between different brands. The changing of fuel tanks for refueling purposes is allowed. There must be an appropriate shut-off valve to control fuel leakage during transfer.

4. Seat padding may be removed or added. Seat must maintain a minimum of six (6) inches in thickness and maintain OEM contour and shape.

5. Insulation may be removed.

6. Access openings for component accessibility will be allowed, but must be closed with material of equal strength and in the color scheme of snowmobile at the start of the race.

7. Any stock qualified chassis that is less than 15 years old is allowed.

8. Tunnel must remain OEM stock width. Chassis 10 number must be stamped in the tunnel, no duplicated chassis numbers; each chassis must have its own unique number.

9. Tunnel and/or bulkhead may be replaced with any stock qualified parts within the brand. Chassis reinforcement allowed. Structural integrity must be maintained.

10. A single foot stirrup loop and/or pad may be added. It must be securely fastened and may not exceed beyond the outside edge of the hood configuration. The maximum length/height is fourteen (14) inches for this device.

11. No front bumpers other than OEM or factory designated replacements will be allowed.

12. The slide lubricant reservoir/tank must be mounted under the running board, under the hood, or in the rear storage compartment. All slide lubricant shall be biodegradable.

1. CDI / ECU module may be reprogrammed.

2. Gauges-tachometers, speedometers and heat gauges may be added or removed. Openings must be closed.

3. Spark plugs, spark plug wires and connector do not have to be OEM.

4. An approved LED taillight must be illuminated whenever the snowmobile is on the racing surface, whether the engine is running or not

5. Headlight may be removed. If left intact headlight must be unplugged. The lens must either be removed or fully taped. If headlight is removed the opening must filled with a solid material.

6. Wiring may be removed.

2. The driver will be given an identifying credential which must be worn until the completion of the race.

3. The same machine and driver must start the race that qualified for the race.

1. A driver must be 18 years of age on the day of qualification trials for the race.

2. Each machine entered in the race must have a team of no less than two (2) and no more than five (5) drivers.

3. All machines entered in the race will pass through a technical inspection two (2) hours prior to the start of the race. The exact time will be announced at the drivers meeting.

4. A pace machine will be used for the start of the race and during the race when safety conditions dictate. Absolutely no passing of the pace sled is allowed. If violated a mandatory penalty will be implied.

5. A race may be declared complete when one machine has completed one lap more than one half the total distance of the event. This is left to the discretion of the race director.

6. A participant is any person taking part in any event sanctioned by or affiliated with International Snowmobile Racing, Inc. in any form, including but not restricted to drivers, sled owners, mechanics, crew members, sponsors, track officials, pit area personnel, manufacturers and press representatives. All such persons shall be considered public figures that have by their own choice become involved in snowmobile racing events, with the full understanding that he or she must abide by the rules and regulations established and published by ISR. All participants are considered responsible for their personnel conduct.