Champ 120 Class Rules

General

1. Snowmobile must be an ISR designated 120/4 stroke model the complies with the General Rules and Regulations section.
2. Engine, frame, hood and slide rails must be oem for the model.

Engine

1. Must start with OEM filed 120/4 stroke engine.
2. Engine components allowed to modify or change from OEM.
   1. Cam shaft- maximum .290 inch lift.
   2. Valves and seats.
      1. Maximum intake valve diameter 25.2 mm.
      2. Maximum exhaust valve diameter 24.2 mm.
      3. Minimum valve stem diameter 5.5 mm.
   3. Valve Springs and retainers.
   4. Tappets and push rods.
   5. Governors may be removed.
3. Engine overbore may not exceed .020" (.50 mm) of standard bore size for the model.
4. Engine stroke must be stock as manufacture's filed specifications.
5. Engine components allowed to modify, but must begin with OEM for engine model.
   1. Bearings
   2. Connecting rod
   3. Piston and Rings
   4. Gaskets
   5. Cylinder head
   6. Cylinder
   7. Crankcase
   8. Rocker arms
   9. Intake manifold
6. Carburetor can be bored and modified, but must begin as OEM supplied for engine model.
7. Any functionally silenced exhaust system may be used. Outlet pipe must point downward and cannot protrude beyond machine width.

Drive

1. Clutching is open. CVT type transmission allowed. Drive components must be commercially available.
2. A metal clutch/chain cover must be in place at all times during operation. It must cover clutches, gears, belts, chains, starter cups and any other rotation components
3. Brakes must be properly operable at all times.
4. Track drive sprockets may be modified or changed.

Ski Suspension and Steering

1. Suspension must maintain OEM concept ( i.e. trailing arm, "A" arm, etc.) Ski suspension and steering may be changed or modified. Materials and components must meet or exceed OEM strength and structural integrity. Must maintain suspension travel with driver seated. No rigid suspensions.
2. The structural integrity of the steering and suspension systems must be maintained.
3. Maximum ski stance is 34 inches (measured between ski runner cutting edges.)
   

Ski and Ski Runner

1. Skis may be changed to commercially available after market skis.
   1. Minimum length for Son-cross is 20 in.
   2. Minimum length for Oval and Ice Drag is 12 in.
   3. Minimum width and turn-up for Oval and Ice Drag are as shown in illustration.
   4. Ski loop must conform to General Rules and Regulations.
2. Ski runners must meet competition and safety requirements for the type of racing (I.E. Oval or Snow cross)

Track Suspension

1. Track suspension may be altered relocated or replaced. Structural integrity must be maintained.
   
2. Suspension must maintain a minimum of 2 inches of useable, vertical travel with the driver seated.
   
3. Track and track suspension must fit and be mounted within the confines of the OEM for the model tunnel.
   
4. Unless contrary to local laws, slide rail lubrication system allowed. Must use biodegradable, non-toxic lubrication.

Track Traction

1. Track must be OEM for a 120/4 stroke model from any snowmobile manufacturer.
2. Track may not be reversed.
3. Traction devices must not extend more than 3/8 inch beyond the highest point of track.

Frame and Body

1. Snowmobile length must not exceed OEM for the model length by more than 2 inches (ski loop to rear of tunnel).
2. Overall body width must be within 2 inches of OEM for the model body width.
3. Bumpers must be padded (no sharp edges exposed).
   
4. Snow flap must be touching ice with driver aboard.
5. Belly pan required
6. Bulkhead may be modified or replaced; it must remain within 1 inch of the length and 1 inch of the width of the OEM bulkhead.

Ignition & Electrical

1. Ignition system must be OEM for model. Flywheel can be lightened. Lighting coil may be removed.
2. Any commercially available flywheel may be used.