600cc Wingless JR Micro Sprint Rules
Age requirement: 12 to 17 years of age. Ages 12-14 must have at least one year of experience. 15-17 years of age may begin in this class with no experience. If your 18th birthday falls during the racing season (May-October) you cannot compete in the class after your birthday.
If a change or modification to the stock engine or its parts is not included in these rules, then the modification is considered legal. a) No limited production race motors allowed. Must be a production motorcycle engine, 4 cylinders, 4 stroke
“Stock” means unmodified factory original parts or components.
No titanium anywhere in or on the engine unless it comes stock form manufacturer of engine on the production bike or used as bolts in aftermarket rods.
Must have engine, clutch, and transmission all in one unit
Must be Chain Drive
600cc Maximum displacement for an engine model that was new in 2006 or newer. Older engines maximum displacement is 637cc. Engine model is defined as a manufacturer redesign of overall engine. See Specification list.
No strokers or de-stroked engines
NO PORTING or deporting of intake or exhaust runners. Valve jobs, valve grinding, valve seating, valve seal modification and valve seat cutting are allowed.
Valve seat inserts may be reworked or replaced with any seat of original dimensions. Any dimensional thickness of the stock inserts may not be increased. Valve seats can be ground with multiple angles. Blending of the valve seat into the head is permitted but cannot extend more than ¼” into the aluminum head measured from where the seat meets the head.
OEM Head only.
Cam may not have a higher lift than the stock factory cam. (duration is open)
Valves cannot be larger in diameter than factory stock valves.
No machining to remove weight from the crank (balancing of crank is ok) (no after-market cranks) (no lightweight cranks) No polishing or coatings of any kind.
No aluminum connecting rods.
No dry sump systems are allowed unless it comes from the motorcycle manufacturer as original equipment.
Clutch/Transmission: No removal of clutch. Clutch must remain operational. No modification of the stock transmission gears, no close ration gears or nonstandard gear-ratios. All gears must remain in the transmission. No coatings or polishing of any kind is permitted.
Ignition: No aftermarket ECU’s, stock appearing ECU only. ECU must be a production ECU that was originally supplied by the same manufacturer as the engine. Racing ECU’s may be used, as long as they were originally supplied by the same manufacturer as the engine. Ex: Honda motorcycle engines must run ECU’s that were supplied by Honda on their motorcycle engines. Re-flashing of ECU and factory race ECU’s are allowed. Rev limit for all 600cc (nothing larger than 600cc) engines is 16,100 rpms.
All cars must have the PA standard connector for the track to check engine rpm rev limit. These are available from the chassis manufactures and engine builders, and at the track. All cars must leave intact the rpm wire coming from the ECU.
No aftermarket coils
No gear position sensor may be used. The sensor may be in place on the engine but cannot have any wires connected to it. Gear position wire from ECU may not be switchable.
No traction control device.
No more than one ECU box present in or on car.
A 50 rpm over rev tolerance for the purpose of tech inspection is acceptable. (Note: this does not mean you can turn up the rpms in any ECU by any amount)
Switchable wires for changing ignition maps, fuel maps, or rev limits must be contained and secured in the wiring harness. (the wires must be taped up, not visible, and unable to be switched in any way)
No mechanically forced induction (turbo charging, supercharging)
Any carburetors may be used on any engine, regardless of year of engine.
If the engine did not come from the factory with fuel injection, fuel injection may not be used.
A muffler must be used with the exhaust system that will keep noise levels within individual track limits.
No removing the charging system, it must remain in complete working order, no factory racing charging systems.
The engine must self-start at the beginning of the event. If it does not self-start, the car may be pushed off and must start at the rear of the event as the penalty.
No fuels other than alcohol, gasoline, and/or top lube. Non-flammable top lube only, no exotic fuel additives, no oxidizers, no fuel enhancer top lube. Fuel tanks must contain a bladder. A fuel tank with a bladder is further defined as a plastic outer shell with a rubber inner container.
***King Racing Products brand restrictor plates are mandatory on all engines.
Stock throttle bodies only, no aftermarket throttle bodies.
No cockpit adjustments of any kind are permitted.
Full containment seat is mandatory.
No more than 2” of spacer material may be used to raise the seat. If the seats needs to be raised more than 2”, the frame seat bar tube must be raised. Adjustable seat height mechanisms may be used if they are properly designed. The shoulder belt tube (the frame bar behind the seat used to prevent forward movement of the shoulder belts) must be located no lower than 3” below the drivers shoulders and no more than ½” above. There needs to be a minimum of 3” of head clearance between the top of the drivers head with the helmet on and the top of the frame when a straight edge is placed across the cage members directly above the head. The driver must be seated in the car in the normal racing position (no crouching).
Halos are mandatory. 3 point minimum (weld in or bolt on). 4 point bolt on is highly recommended.
Minimum weight is 775 lbs. If weight is added it must be firmly bolted in place.
Seat belts must be 3" wide, 5 point approved racing harness, no more than 2 yrs. old. Helmet and approved full face shield required. Approved fire suit mandatory; (NOMEX underwear, head sock, two-layer suit is highly recommended). All single layer fire suits must wear NOMEX underwear. Arm restraints, “Hans” or similar restraint, and racing gloves must be worn at all times. No neck collars permitted.
MyLaps transponder is required. Transponder location is 21” from center of front axle towards rear axle and 6” from the bottom frame rail.
Fire Suppression Kits are recommended for 2021. They will be mandatory for all non-bladder cars in 2022.
Fire extinguisher and first aid kits required in haulers.