3. 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.
4. 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.
5. No changes in engine dimensions can be made by gasket adjustments. Gaskets may be trimmed but must remain OEM and OEM thickness.
6. Maximum cylinder overbore for wear or cylinder repair cannot exceed .020 inches (1/2mm).
7. Stock OEM pistons only are allowed for replacement.
8. 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.
9. No additional fuel pumps may be added.
10. 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.
11. The exhaust system “wye pipe” must be OEM for the model and be mounted in the OEM location for the model.
12. Throttle lever may be replaced but must be thumb operated with a direct mechanical operated mechanism on rear side of right handlebar.
CARBURATION
1. The carburetors must be the originally specified size and configuration for the engine.
2. Carburetors may not be changed, altered, modified, in any manner.
3. The only allowable tuning components shall be the MainJet, Pilot Jet, Jet Needle, Needle Jet, and throttle Slide. NoPower Jets or aftermarket systems allowed. No UFO’s.
4. Any method of filtering air to the carburetor may be used. Airbox,Baffle plenum, K&N or comparable filter, or no filtration at all are legal for the class.
EXHAUST
1. The stock factory “wye” pipe must be used with no alterations.
2. Any expansion chamber may be used in conjunction with the stock “wye” pipe, but must be effectively silenced.
1. The engine must be a fan cooled engine from an ISR Stock Qualified snowmobile and may not exceed 600 cc in total volume. These engines must also be from models inclusive in the 15 year production requirements.
2. Air Box/Plenum may be removed.
3. 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.
4. 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.
5. No changes in engine dimensions can be made by gasket adjustments. Gaskets may be trimmed but must remain OEM and OEM thickness.
6. Maximum cylinder overbore for wear or cylinder repair cannot exceed .020 inches (1/2mm).
7. Stock OEM pistons only are allowed for replacement.
8. 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.
9. CDI/ECU module may be reprogrammed.
10 . No additional fuel pumps may be added.
11. 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.
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.
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.
1. Front suspension components (arms, spindles, rod ends, spherical joints, the rods linkages, IFS trailing arms and radius rods) may be altered or replaced. Maximum overall width is 45 inches.
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. Snowmobile must maintain two (2) inches of useable vertical suspension travel.
6. Handlebars, column and controls may be altered or replaced. Aluminum handlebars allowed if produced by the OEM manufacturer.
1. Skis may be altered or replaced.
2. Track suspension may be altered or replaced.
3. Rear suspension to tunnel mounting locations is not restricted; safety and structural integrity must be maintained.
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 103 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.
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 (CDI box, flywheel, and stator) must be OEM for the model engine. No modification allowed.
2. CDI module may be reprogrammed.
3. Fixed ignitions may be moved (+or – ) 4 degrees.
4. A taillight using an approved LED light illuminated at all times the sled is on the racing surface whether the engine is running or not is required .
5. Instruments, gauges and headlights may be altered, removed or replaced.
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