Sprint 600 Stock Fan Rules

1. Only single-track snowmobiles may compete in the Sprint 600 Stock Fan Class.
2. Any changes or alterations allowed in the Stock classes are permitted in the Sprint 600 Stock Fan class.
3. The brand of engine, hood and logo need not match.
4. All snowmobiles must comply with GENERAL RULES AND REGULATIONS section.
5. Snowmobile must weigh a minimum of 350 pounds.  Maximum overall width is 45 inches.
6. Ballast may be used to equalize weight.  Ballast must be securely contained.
7. The rules for this class will be in place for a period of 5 years, (6-1-2009 to 6-1-2015) with the exception of rules affecting the “Track and Traction” section. (See rules number 2.and 4) Rules concerning safety requirements may change at any time with a two week notice.

Engine

1. The designated engine must originate from an ISR stock qualified production snowmobile conforming to the ISR 15 year production designation, two (2) cylinder stock production engine. The engine must originate from a production model using a 475 cc or larger engine.   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.  Blueprinting will not be allowed. No removal of material whatsoever will be allowed. This is to include polishing, port matching, deburring, abrasive blasting or material removal for the purposes of engine balancing or other reasons.
2. No changes in engine dimensions can be made by gasket adjustments.  Gaskets may be trimmed but must remain OEM and OEM thickness.
3. Maximum cylinder overbore for wear or cylinder repair cannot exceed .020 inches (1/2mm).
4. Stock OEM pistons only are allowed for replacement.
5. No additional fuel pumps may be added for fuel delivery purposes.
6. Stock production carburetors for the engine series must be used. No modifications to these carburetors will be allowed. Only production tuning components may be used for tuning purposes. No power jets, no auxiliary air jets, no slide inserts, or aftermarket components designed to alter fuel flow, air flow, or carburetor placement will be allowed.
7. Air box may be removed or replaced.
8. Oil injection pump may be removed.
9. Engine torque arms, limiters, snubbers, and suppressors may be used.
10.  A  OEM Wye (Y) pipe for the engine series must be used.
11. A  OEM Exhaust expansion chamber for the engine series must be used. Allowable modifications to the expansion chamber are as follows:
12. After muffler/silencer canister may be removed.
13. Exhaust stinger may be modified or changed.
14. The expansion chamber proper must be maintained with no modifications. This is subject to the Technical Director’s decision and may not be appealed.
15.  Exhaust must be functionally silenced.
16.  Chassis design must accommodate the exhaust system, no changes to the exhaust system for chassis fit are allowed.

Drive

1. Any commercially available drive and driven clutches and internal components may be used.  Clutches and components may be modified.
2. Chain case and internal components may be altered, removed or replaced.  Chains and sprockets may be altered, removed or replaced.
3. Jackshaft/track shaft may be altered, removed or replaced.

Ski Suspension & Steering

1. Front Suspension components (arms, spindles, rod ends, spherical joints, tie rods and linkages, IFS trailing arms and radius rods) may be altered or replaced.
2. Front suspension springs may be altered or replaced.
3. Sway bars and links may be altered, removed or replaced.
4. Shocks and TSS struts may be altered, removed or replaced. 
5. Suspension must maintain two (2) inches of useable vertical travel with the driver on the snowmobile.
6. Handlebars, column and controls may be altered or replaced.  Aluminum handlebars allowed if produced by the OEM manufacturer.

Ski & Ski Runners

1. Skis may be altered or replaced. Must conform to General Snowmobile requirements.

Track Suspension

1. Track suspension may be altered or replaced.
2. Rear suspension to tunnel mounting locations is not restricted; safety and structural integrity must be maintained.
3. Suspension must maintain two (2) inches of useable vertical travel with the driver on the snowmobile.

Track & Traction

1. No cleated tracks allowed.  Track must be commercially available, one-piece, molded rubber track.  Track must be used as produced by the molder of the track.  No modification allowed unless specified.
2. Minimum width is 13.5 inches.  Minimum length of track is 106 inches.  Minimum lug height is ½ inch.
3. Track must be “R” rated from the molder.  It is recommended that the track be no more than 3 years old.
4. The use of 106 tracks is under a 1 year review, after review at Spring race rules 2010 meeting, it is possible that 106 inch tracks may not be allowed to compete.

Frame & Body

1. Chassis/frame origination and modification are not limited or restricted.  Maximum width is 45 inches.
2. Any hood allowed.  May be cut out behind the windshield for additional venting.  Headlight fairing or cowling may be removed.  Dash and/or console may be altered, removed or replaced.
3. Windshield not required.
4. Fuel tanks may be altered or replaced.
5. Seat may be altered or replaced.

Ignition & Electrical

1. Ignition system must be OEM for the model without modification.
2. Instruments, gauges and headlights may be altered, removed or replaced.
3. A red LED taillight must be illuminated whenever the sled is on the racecourse, whether the engine is running or not.

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