Pure Stock

Pure Stock Class

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. Any stock production 600 cc snowmobile is allowed, no special builds or 600 cc Super Stock sleds will be allowed.
4. Removal of any material from total snowmobile 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. Stock 600 engine limitations for 4-stroke powered models.

ENGINE

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 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.
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 modification 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 will remain in place and be functional.
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. The exhaust system must be OEM for the model and be mounted in the OEM location for the model.
13. Throttle lever may be replaced but must be thumb operated with a direct mechanical operated mechanism on rear side of right handlebar.

drive

1. Clutches must be OEM for the model.
2. No machining, grinding, cutting or welding allowed on clutches unless otherwise specified.
3. Primary clutch - any combination of OEM for the brand, properly filed, springs, weights, and ramps may be used.  Metal may be removed but not added to ramps or flyweights in the primary clutch.
4. Secondary clutch – helixes must be OEM for the brand and properly filed.
5. No machining on the clutches to accommodate springs, weights, helixes.
6. Drive chain sprockets may be changed provided that they are options filed by the manufacturer.
7. Track drive axle, track drive sprockets and non-driving wheels may not be replaced.  No material substitution allowed. 
8. Brake components must be OEM for the model and brand. Aftermarket pads allowed. Drive belts do not have to be OEM.

ski suspension & steering

1. Ski suspension and steering must be OEM for the model unless otherwise specified.
2. 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.
3. The ski stance distance must be centered on the center of the tunnel.
4. Titanium springs not allowed unless OEM for the model.
5. Limiter straps allowed, but snowmobile must retain two (2) inches of vertical travel. Travel will be measured at the front and rear bumper.
6. 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.

skis & ski runner

1. OEM (for the brand) skis only.  Must conform to General Competition Rules. 
2. Reinforcement is allowed on the top of the ski board only.
3. Carbide cutting edge must be mounted in a host bar meeting current ISR rules. No more than 10 inches of cutting edge allowed.

track suspension
1. Track suspension must be used as provided by OEM. Limiter straps allowed, but snowmobile must retain two (2) inches of vertical travel. Travel will be measured at the front and rear bumper. Front suspension shock spring may be modified, changed or removed. Rear suspension front shock may be removed, but if used, may not be modified or altered, and must remain in OEM mounting location.
2.  Titanium springs not allowed unless     OEM for the model.

track & traction

1. OEM track for the model and brand must be used.
2. The track must be used as produced by the molder of the track.  No cutting or other modifications allowed.

frame & body

1. OEM windshields for the model only.  The windshield may be altered for driver safety and comfort, but must extend five (5) inches above the highest part of the cowl.  Windshield must have a safety edging.  Windshield must remain in OEM mounting location.  Windshields must be intact at the start of the race.
2. Fuel tank must remain OEM for the model.  The fuel tank is the only tank that can be used for fuel.
3. Seat must be OEM for the brand. 
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 reprogrammed.
3. Fixed ignitions may be advanced or retarded a maximum of 4°.
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 at all times while on the racing surface, whether the engine is running or not.
7. Gauges-tachometers, speedometers and heat gauges may be added or removed.  Openings must be closed.

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

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