PRO-STOCK RULES 

GENERAL 

1. Pro Stock snowmobiles must retain OEM stock appearance for the model (hood, seat, engine and tunnel must retain OEM appearance and dimensions.) Like chassis may be interchanged with in the brand.
2. There will be three (3) Pro Stock classes.

 NOTE: MINIMUM COMBINED WT. is the weight of the sled, fuel, driver, and driver gear. 

3. Machine movement will be from Stock to Pro Stock. Any snowmobile may be reclassified and assigned in the interest of fair competition.
4. Sled must begin as a qualified stock snowmobile.  All sleds must comply with the GENERAL RULES AND REGULATIONS section.
5. Any alterations allowed in Stock classes are also allowed.
6. No weight belts or loose objects may be worn by driver.
7. Ballast weight must be securely fastened to the machine. Securely fastened means a grade 5 5/16 inch bolt with self locking nut.

ENGINE 

1. The engine may be moved from its OEM location and remounted a maximum of one (1) inch in any direction, which is perpendicular to the centerline of the crankshaft. The crankshaft may not be moved within the crankcase.
2. Crankcase, cylinders and crankshaft must be from the same model. These components may be modified internally provided the engine retains its complete external stock appearance and dimensions.  Must retain original number of cylinders.

1. Four cylinder crankshaft gears may be changed with any OEM crankshaft gear.
2. Cylinder maximum overbore is defined as 2% over the cc displacement for the class.
3. Cylinder may be bored or sleeved down.
4. OEM cylinder outer shell dimensions modification must be within .020 inches per side / .040 overall of the OEM cylinder.  Modification must be blended into original casting to retain OEM appearance.
5. Cylinder height may be modified to change port height.  If a plate is used to raise cylinder height, the plate, including gaskets, cannot exceed ½ inch.

3. Engine components allowable for modifications or replacement:
   1. Heads
   2. Bearings
   3. Rods
   4. Pistons, pins and rings.
   5. Gaskets
   6. Manifolds  (intake)
   7. Carburetors (no super charging, turbo charging or aftermarket fuel injection will be allowed.)  Intake concept and location must remain OEM for the model.  A maximum of one venture per cylinder will be allowed.
   8. Air boxes may be removed.
   9. Motor mounts
   10. Reeds and reed blocks may be changed if the do not change the outside dimensions of the cylinder or crankcase. External plate may be thicker.  Pro Stock 1000 reed cages may be modified. No welding allowed. Reed cage changes must accomplished by bolting only.
   11. Fuel pump
4. Dual spark plugs allowed as long as stock appearance is not compromised.
5. Engine must retain original cooling concept. Cooling circuits may be modified or removed.
6. Water pumps may be removed.
7. Radiators and ducting may be used but may not change OEM appearance.
8. Any exhaust modification or replacement is allowed, with the exception on megaphones.  The exhaust system emission pipe must not protrude more than three (3) inches beyond the chassis or hood configuration.  Exhaust system must be functionally silenced. Any functionally silenced exhaust will be allowed. Unsilenced pipes allowed on machines built prior to 2004. Exhaust emission pipe must not protrude more than three (3) inches beyond the chassis or hood configurationat its furthest point.

DRIVE 

1. Any CVT clutches allowed.
2. Clutch jackshaft may be changed or modified (no welding on jackshaft)
3. The jackshaft and track drive axle may be moved from their OEM locations a maximum of one inch in any direction which is perpendicular to the centerline of the shaft.
4. Chain case and cover may be from any stock qualified model within the brand.  Chain case may not be modified.
5. Minimum brake disk diameter is 7 inches (if disk is mounted to track drive axle and a dual opposing piston caliper is used, the disk minimum diameter is 6 inches.)
6. Brake caliper may be either dual opposing piston or single piston type.

SKI SUSPENSION & STEERING 

1. Material substitution is allowed. OEM appearance must be maintained.
2. Front suspension components including struts, arms, spindles, rod ends, spherical joints, tie rods, linkages, IFS trailing arms and radius rods must remain OEM design. Must remain in the OEM location on the chassis.
3. Any shock absorber allowed. Must remain OEM location on the chassis.
4. Spindles may be strengthened or replaced with a stronger spindle. Spindle height must remain within 10% of the original OEM dimensions.
5. Minimum ski stance (center to center of the ski runners) is 40 inches.
6. Ski widening devices allowed.  Maximum overall width is 45 inches.
7. Handle bars, grips and controls may be modified.

SKIS & SKI RUNNERS 

1. Any OEM or aftermarket ski may be used provided the original spring concept remains the same.  Minimum length is 20 inches.
2. It is highly recommended, if a cutting edge is used on a ski, that no more than 5 inches 90% cutting edge be used on a ski.
3. Ski loop must be designed to prohibit ski interlock with any other component while driver is on the machine.

TRACK SUSPENSION 

1. Any track suspension is allowed.
2. Any shocks are allowed. Out board shock do not compromise OEM stock appearance.
3. Dual limiter straps required.  One inch of travel required with driver sitting on the machine.

TRACK & TRACTION 

1. Any commercially available replacement rubber track available through a three tier distribution system allowed.
2. Track must remain untouched (no trimming)
3. Belt tracks (speed belts) allowed. Minimum width is 11.25 inch with a 1/8^th inch variance
4. Except for under slide rails, all plates will be no greater than 2.25 inches in width and length. Kicker plate must be located under slide rail and be no longer than 3.25 inches and no wider than 1.25 inches.
5.  Machine must maintain twenty inches of track length on the course surface when machine is under full power.

FRAME & BODY 

1. Chassis including front bulkhead must retain OEM appearance and dimensions for the model.  Material substitution is allowed.  Steel may be substituted with aluminum. Tubular front end are not allowed.  The race director shall have the authority to determine structural integrity.
2. Openings must be closed, Cowling, etc. may not be cut or shaved down (OEM appearance must be maintained.)
3. Access opening s for component accessibility will be allowed, but must be closed with original type materials.
4. Chassis reinforcement will be allowed.  No lightening holes can be drilled that alter the outside appearance for the model. Structural integrity must be maintained.
5. Machines will have a sheet of metal the same thickness as the tunnel permanently fastened to the topside of the tunnel.  The sheet of metal shall be the same width as the tunnel and shall extend from the rear of the tunnel to the bulkhead.
6. Hood to belly pan molding must remain intact. The molding may be lightened as long as it does not alter the outside OEM appearance.
7. Any insulation can be removed.
8. Seat must remain stock appearing. Seat may be lowered  but must be at least two inches thick at its minimum dimension.
9. The fuel tank may be modified to accommodate a fuel cell. The outside gas tank shell must remain intact. The fuel cap may be replaced with the fuel cell cap. The use of a fuel cell is used with the above rule will not compromise OEM appearance.
10. Except for front air dam (which requires 2inches clearance.), all other parts and components must maintain a minimum of 1 inch ground clearance with the suspension fully compressed.

IGNITION & ELECTRICAL 

1. Any ignition allowed.
2. Any instrumentation is allowed.
3. Electrical wiring may be removed.

PRO STOCK 1000 

ENGINE 

1. Any aftermarket cylinder is allowed in Pro Stock 1000. Aftermarket cylinders must be commercially available. Cylinders may not be interchanged between brands.
2. The read valve mounting area on the crank case may be modified to change reed angle.  The upper surface of the intake tract may be reinforced by welding or bonding.