Pro Stock Rules
- 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.
- There will be three (3)
Pro Stock classes.
NOTE: MINIMUM COMBINED WT.
is the weight of the sled, fuel, driver, and driver gear.
- Machine movement will be
from Stock to Pro Stock. Any snowmobile may be reclassified and assigned in
the interest of fair competition.
- Sled must begin as a
qualified stock snowmobile. All sleds must comply with the GENERAL RULES
AND REGULATIONS section.
- Any alterations allowed
in Stock classes are also allowed.
- No weight belts or loose
objects may be worn by driver.
- Ballast weight must be
securely fastened to the machine. Securely fastened means a grade 5 5/16
inch bolt with self locking nut.
- 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.
- 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.
- Four cylinder
crankshaft gears may be changed with any OEM crankshaft gear.
- Cylinder maximum
overbore is defined as 2% over the cc displacement for the class.
- Cylinder may be
bored or sleeved down.
- 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.
- 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.
- Engine components
allowable for modifications or replacement:
- Pistons, pins and
- Manifolds (intake)
- 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.
- Air boxes may be
- Motor mounts
- 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.
- Fuel pump
- Dual spark plugs allowed
as long as stock appearance is not compromised.
- Engine must retain
original cooling concept. Cooling circuits may be modified or removed.
- Water pumps may be
- Radiators and ducting
may be used but may not change OEM appearance.
- 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.
- Any CVT clutches
- Clutch jackshaft may be
changed or modified (no welding on jackshaft)
- 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.
- Chain case and cover may
be from any stock qualified model within the brand. Chain case may not be
- 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.)
- Brake caliper may be
either dual opposing piston or single piston type.
SKI SUSPENSION & STEERING
- Material substitution is
allowed. OEM appearance must be maintained.
- 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.
- Any shock absorber
allowed. Must remain OEM location on the chassis.
- Spindles may be
strengthened or replaced with a stronger spindle. Spindle height must remain
within 10% of the original OEM dimensions.
- Minimum ski stance
(center to center of the ski runners) is 40 inches.
- Ski widening devices
allowed. Maximum overall width is 45 inches.
- Handle bars, grips and
controls may be modified.
SKIS & SKI RUNNERS
- Any OEM or aftermarket
ski may be used provided the original spring concept remains the same.
Minimum length is 20 inches.
- 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.
- Ski loop must be
designed to prohibit ski interlock with any other component while driver is
on the machine.
- Any track suspension is
- Any shocks are allowed.
Out board shock do not compromise OEM stock appearance.
- Dual limiter straps
required. One inch of travel required with driver sitting on the machine.
TRACK & TRACTION
- Any commercially
available replacement rubber track available through a three tier
distribution system allowed.
- Track must remain
untouched (no trimming)
- Belt tracks (speed
belts) allowed. Minimum width is 11.25 inch with a 1/8th inch
- 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.
- Machine must maintain
twenty inches of track length on the course surface when machine is under
FRAME & BODY
- 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.
- Openings must be closed,
Cowling, etc. may not be cut or shaved down (OEM appearance must be
- Access opening s for
component accessibility will be allowed, but must be closed with original
- Chassis reinforcement
will be allowed. No lightening holes can be drilled that alter the outside
appearance for the model. Structural integrity must be maintained.
- 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.
- Hood to belly pan
molding must remain intact. The molding may be lightened as long as it does
not alter the outside OEM appearance.
- Any insulation can be
- Seat must remain stock
appearing. Seat may be lowered but must be at least two inches thick at its
- 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.
- 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
IGNITION & ELECTRICAL
- Any ignition allowed.
- Any instrumentation is
- Electrical wiring may be
PRO STOCK 1000
- Any aftermarket cylinder
is allowed in Pro Stock 1000. Aftermarket cylinders must be commercially
available. Cylinders may not be interchanged between brands.
- 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.