2011 600cc Micro Sprint Universal Engine Rules

1. Terms and conditions
a) If a change or modification to the stock engine or its parts is not included in these rules then
the modification is considered legal.
b) The word “Stock” means unmodified factory original parts or components.
2. Overall Engine
a) No limited production race motors allowed. Must be a production motorcycle engine, 4
cylinders, 4 stroke
b) No titanium anywhere in or on the engine, unless it comes stock form manufacturer of engine
on the production bike
c) Must have engine, clutch, and transmission all in one unit
d) Must be Chain Drive
3. Bore and stroke
a) 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.
b) No strokers or de-stroked engines
4. Head and cams
a) NO PORTING or blending the bowls.
a. Valve jobs, valve grinding, valve seating, valve seal modification and valve seat cutting
are allowed.
b. 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.
b) No custom made heads.
c) Cam may not have a higher lift than the stock factory cam. (duration is open)
d) Valves can not be larger in diameter than factory stock valves.
5. Bottom End
a) No machining to remove weight from the crank (balancing of crank is ok) (no after-market
cranks) (no lightweight cranks)
b) No after-market connecting rods. Must use stock factory connecting rods.
a. Aftermarket rod bolts may be used
c) No dry sump systems are allowed unless it comes from the motorcycle manufacturer as
original equipment.
6. Clutch/Transmission
a) No removal of clutch.
a. Clutch must remain operational
b) No modification to the stock transmission gears, no close-ratio gears or nonstandard gearratios.
All gears must remain in transmission, no removing any gears.
7. Ignition
a) No aftermarket ignition systems, must use factory Stock or factory racing ECU, No hot ECU
boxes, no physically modified ECU boxes. Factory race boxes are ok, but must have the rev
limit set to the street bike stock rev limit. Stock Rev Limiter must remain intact at all times
(ex: no switched or gear specific limiters). If a computer is hooked up to check the ECU it
must be set to factory stock specifications, no tolerance. See specifications list for RPM limits.
b) 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.
c) May use different year ignitions from same manufacturer as long as stock rev limit of engine
(not ignition) is retained.
2011 600cc Micro Sprint Universal Engine Rules
d) No aftermarket coils
e) No gear position sensor may be used. The sensor may be in place on the engine, but can not
have any wires connected to it. Gear position wire from ECU may not be switchable.
f) No traction control device.
g) No more than one ECU box present in or on car.
h) A 150 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, this is information for
the tech inspector only)
8. Air Induction system
a) No mechanically forced induction (turbo charging, supercharging)
b) Any carburetors may be used on any engine, regardless of year of engine.
a. Note: Switching to carburetors on engines that came with fuel injection usually increases
the rev limiter due to the removal of the injectors as the ECU cuts fuel to limit rpm’s
before it cuts the ignition. A reflash of the ECU will be required if using carburetors in
order to comply with the rev limit rule 7. a)
c) If the engine did not come from the factory with fuel injection, fuel injection may not be used.
d) No after market throttle bodies.
9. Exhaust
a) A muffler must be used with the exhaust system that will keep noise levels within individual
track limits.
10. Charging system
a) No removing the charging system, it must remain in complete working order, no factory
racing charging systems.
11. Self Starting
a) 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.
12. Fuel
a) 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.
b) 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.
13. Minimum weight
c) Minimum weight at all times is 775 pounds for winged classes and 750 pounds for wingless
classes, car and driver. If weight is added it must be firmly bolted in place.

NOTE: ANYTHING NOT COVERED IN THESE SPECIFICATIONS WILL BE THE DISCRETION OF THE TRACK PERSONNEL WITHOUT RECOURSE FROM ANY DRIVER OR OWNER ALL SPECIFICATIONS ARE SUBJECT TO REVISION.

For more information call Roger Gettel at (717) 532-8581