MIRA
SUPER STOCK 600
In stock and stock based classes, no changes or modifications are allowed unless specifically allowed by these rules. If these rules do not specifically allow a change or modification, then it must be assumed that the change or modification is not allowed.
All highlighted areas are MIRA only rules. These rules are not legal in other areas (i.e. Eagle River, USSA, EPT or WSA) .
STOCK SNOWMOBILE GENERAL REQUIREMENTS
1. Snowmobile must comply with the GENERAL RULES AND REGULATIONS section.
2. The snowmobile must have original OEM (or factory designated replacement) engine, frame, hood and clutches supplied by the manufacturer for that particular model. All components must be OEM for the model and year, or properly filed OEM replacement parts that supersede the original OEM parts. Factory options are NOT allowed unless otherwise specified.
3. Removal of any material from total snowmobile by means of heat, acid, drilling, sandblasting, peening, substitution, or total elimination will not be allowed unless otherwise specified in this section.
4. Super Stock 600 engine limitations for 2-stroke power models.
Maximum displacement 600cc
Number of cylinders 2
Maximum effective
compression ratio 6.8:1
Maximum carb size 40 mm
Maximum EFI size 46 mm
5. Super Stock 600 engine limitations for 4-stroke powered models.
Engine layout inline 3 cylinder
Without drive
Clutch gear
Reduction
Minimum stroke 66 mm
Maximum displacement 1050 cc
Maximum carburetor bore 40 mm
Maximum EFI throttle
body bore 42 mm
max compression ratio 11.8 to 1
ENGINE
2007 and older enduro engines may use modified cylinders and cases until 2010. These older engines must still comply with all the other stock rules (i.e. stock heads, stock “wye” pipe ect…) however no 2008 engine parts may be used on older engines.
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. 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 sandblasting 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.
4. Maximum cylinder overbore for wear or cylinder repair cannot exceed .020 inches (1/2mm)
5. Stock OEM pistons only are allowed for replacement.
6. OEM carburetor slide valve and replacement jet components without modification will be allowed in all stock classes. No modifications to carburetor body will be allowed.
7. CDI/ECU module may be reprogrammed.
8. No additional fuel pumps may be added.
9. Oil injection pump must remain in place and remain functional. Lines may be removed and plugged. Premix gasoline may be used. Stand alone oil injection tanks may be removed.
10. Thermostats may be altered, removed or replaced.
11. Cooling system must remain in the OEM location except that tunnel mounted heat exchangers may be relocated for stud clearance, but must remain within the confines of the tunnel.
12. Any commercially available after market single exhaust pipe may be used. However the Stock for the model “wye” pipe must be maintained.
13. Any stock EFI engine can use a fuel flow modifier (i.e. boondocker) when used in conjunction with an after market pipe.
14. The 4-stoke engines can use any commercially available exhaust pipe.
15. The 4-stroke EFI engines can use a fuel flow modifier in conjunction with an after market exhaust pipe.
DRIVE
1. Any OEM or aftermarket clutch is allowed.
2. Primary clutch – any combination of springs, weights, and ramps may be used. Metal may be removed but not added to ramps or flyweights in the primary clutch.
3. Secondary clutch – Helixes may be machined for angle change. No material may be added. No welding will be allowed.(billet helixes allowed)
4. Drive chain sprockets may be changed provided that they are options filed by the manufacturer.
5. Track drive axel, track drive sprockets and non driving wheels may be replaced. No material substitution allowed. No modification to chassis or drive parts allowed accomplishing axel and or sprocket replacement.
6. Brake components may be replaced. Brake components must be commercially available and must not be modified. If brake system is relocated, The OEM for the model brake disc must remain in its OEM for the model location. Liquid cooled systems allowed. Brake disc must be OEM (for the model) material and must be at least as large in diameter and as thick as OEM for the model disc.
7. Drive belts do not have to OEM.
SKI SUSPENSION & STEERING
1. Ski suspension and steering must be OEM for the model unless otherwise specified.
2. The steering column may be relocated to suit the driver.
3. Maximum ski stance is 43.5 inches measured between the ski runner cutting edges under the spindle. Ski runner cutting edges must be centered on the ski board and on the spindle.
4. the ski stance distance must be centered on the center of the tunnel.
5. OEM for the model front suspension concept must be maintained (i.e. trailing arm or “A” arm)
6. 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.
7. Sway bars may be maintained.
8. Limiter strap allowed, but must maintain 2 inches of useable downward travel with the driver seated. Travel measured at the front bumper.
9. Handel bars may be replaced, including extensions to fit the driver. All ends must be plugged. The handle bar must be of the same material with the same wall thickness or greater, and tubing outside diameter.
10. Throttle lever may be replaced but must be thumb operated with a direct mechanical operated mechanism on the rear side of right handle bar.
SKI & 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 ¼ inches.
3. Reinforcement is allowed on top of the ski board only
TRACK SUSPENSION
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 rider seated.
3. Track and track suspension must fit and be mounted within the confines of the OEM for the model tunnel.
TRACK & TRACTION
1. Any commercially available one-piece molded rubber track allowed. No cheated tracks allowed. Track must fit within the confines of the OEM for the model tunnel without modification to the track, drive system or tunnel(track suspension relocation holes may be added to the tunnel)
2. The track must be used as produced by the molder of the track. No cutting or other modifications allowed.
3. Traction products must conform to oval sprint requirements (3/8 inch stud rule).
FRAME & BODY
1. OEM windshields for the model only. The windshield may be altered for the driver safety and comfort but must extend five inches above the highest part of the cowl. Windshield must have edging. Windshield must remain in OEM mounting location. Windshields must be intact at the start of the race.
2. Any commercially available fuel tank may be used. Maximum fuel capacity 13 U.S. gal.
3. Seat must be OEM for the brand. Seat contour must remain OEM. Padding may be added or removed. Minimum thickness of padding is 6 inches at the lowest point unless OEM produced with less. Seat must be upholstered.
4. Existing vents may be used to direct cooling to the braking mechanism. Removal of stock air vent grills including intake or exhaust is not allowed. No additional venting allowed. Protective taping or screening is restricted to the external opening only.
IGNITION & ELECTRICAL
1. Ignition must be OEM for the year and model.
2. CDI/ECU module may be programmed.
3. Fixed ignitions may be advanced or retarded a maximum of 4 deg.
4. No aftermarket device allowed which interrupts ignition for the purpose of launch control or traction control unless OEM for the model.
5. Headlight must be OEM for the model, and remain in place. Glass lenses must be taped.
6. OEM taillight must be illuminated.
7. Gauges-tachometers, speedometer and heat gauges may be added or removed. Openings must be closed.
8. Spark plugs, spark plug wire and connector do not have to be OEM.
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