1. All cars should be constructed to look like microsprints. All cars must be equipped with complete body
panels (hood, tail, side panels, belly pan, etc.)
2. Roll cages must be of a 6 point design. Main cage must be 1.25” tubing (.065” wall if using chrome moly,
.120” wall if using mild steel). All bends must be made of a 3” minimum radius (no square or pointed
3. Kill Switch – MANDATORY, must be within reach of driver. Preferred location is on the right side of dash.
Should be visible to safety crews and clearly labeled.
4. Belly pan must extend from the front of the seat to the nose of the car.
5. Must be equipped with fuel cell or tail tank. Fuel bladder or sprint type fuel cell HIGHLY
RECOMMENDED. Must be fully protected and securely mounted. Must be separate from the drivers
compartment. No pressurized fuel systems.
7. All steering and suspension parts that are bolted together must use locking nuts, safety wire, or cotter
8. All cars must be equipped with nerf bars extending to at least the inside edge of the front tire and middle
of the rear tire. May not extend beyond the outside of the tread width of any tire. Minimum diameter ¾” O.
D., .065” wall mild steel. No sharp or pointed edges.
9. Bumpers – Must be present front and rear. Must be securely attached and suitable for towing. Width
may not extend past outside of main frame rail.
10. Must be chain drive. No centrifugal clutches or belt drives. No shaft drive.
11. 5 point racing harness mandatory, minimum width of 2 ½”. May not be more than 5 years old.
12. With driver seated in car, the driver’s helmet may not be higher than the bottom of the upper roll bar.
13. Brakes must be of hydraulic type and sufficient strength as to stop the wheels in the pits or stop the
car while in motion on the track. Must have brakes on the rear axle. Front wheel brakes optional.
14. Car must be equipped with a fuel shutoff valve and kill switch. Both must be functional, within reach of
the driver, and clearly marked.
15. Throttle must be foot operated. Return strap highly recommended.
16. NO electronic traction control devices permitted.
17. Radiators/oil coolers should be mounted in a manner that makes it highly unlikely that it will be
contacted by another car. May NOT be mounted in drivers compartment.
18. No sail panels allowed on any part of car, including sidebars. “A” panels may not protrude more than 2
inches behind rear down tubes.
19. Sides of chassis must have panels installed. Must have sprint type tail tank. Must run sprint or modified
20. Screen over windshield area highly recommended.
21. Suspension on all 4 wheels. May be of coil over, torsion bar, or leaf spring design.
22. Steering mechanism must be constructed of a minimum of 5/8” rod and 3/8” heims. Steering wheel hub
must be of quick release or pin style.
23. All radius tubes should be a minimum of 9/16” diameter with a wall thickness of .120”.
24. Wheelbase - 50” minimum, 72” maximum.
25. Overall width - Shall remain between 58”-65” sidewall to sidewall.
26. All wheels must be race approved, 10 inch diameter only. Steel, aluminum, or carbon fiber wheels are
acceptable. Beadlocks recommended.
27. One piece live rear axle only. No quickchange or differential type rear ends. No accessories (hubs,
sprocket, etc.) may be welded to the axle. Nut or snap ring must be present at end of axle to prevent
wheels from coming off.
28. A firewall must separate driver from engine compartment.
29. All bolts should be grade 5 minimum and should use locknuts, lock washers, or be safety wired or
30. Sprint car type window net RECOMMENDED on left side of the cage.
31. Torque arm must be secured by a minimum ¼” cable or chain, or other reasonable safety device.
32. All cars must have a top wing at all times. Must be securely fastened. If damaged during race, car may
continue provided it is still reasonable secure. NO CARS WILL RUN WITHOUT TOP WING!
Top wing may not exceed 16 sq. ft., 48” long x 48” wide maximum. Side panels must not obstruct the view of
the driver. 22” tall, 56” long right side board maximum (may taper down at front). 28” tall x 56” long left side
board maximum. Wing sliders permitted.
33. Nose wings allowed. Maximum size 28” x 18”. Must not mount forward of front bumper.
34. Wet cell battery mounted in the cockpit must be covered and vented.
35. All added weights must be painted white with car number clearly marked on it. Weights must be
securely fastened with locknuts, or must be drilled and secured with a cotter key.
Engine Rules: 600cc Micro Sprint Universal Engine Rules as follows:
600cc Micro Sprint Universal Engine Rules
1. Terms and conditions
a) Internal Stock parts – must use stock original manufacturer parts for the particular year and make 2. Overall Engine
engine, these parts can not be modified except where noted, if the rules do not state that you can do
it, you can not do it. No mixing of parts from different year and make engines, even if made by the
same manufacturer. Non stock or modified stock external bolt on parts may be used (example: billet
oil pan, starter, water pump cover, oil cooler, pipes, valve covers, etc.)
a) Must be a Production Motorcycle Engine, 4 cylinders, 4 stroke. No limited production race motors 3. Bore and stroke
allowed, only US street legal bike motors are allowed.
b) Current year engines allowed c) No Titanium anywhere in or on the engine, unless it comes stock
form manufacturer of engine on the production bike
d) Must have engine, clutch, and transmission all in one unit
e) Must be Chain Drive
f) Manual cam chain tensioners are allowed.
a) 600cc Maximum for engine model that was new in 2006 and up. Other engines are 637cc 4. Head and cams
maximum. Engine model is defined as a manufacturer redesign of overall engine. See Specification
b) Standard Stroke only (no strokers)
a) NO PORTING or Blending the bowls.5. Pistons
b) Valve jobs, valve grinding, valve seating, valve seal modification and valve seat cutting are
c) 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.
d) Cams do not need to be stock, but the lift must be no greater than stock. (duration is open)
e) Cam timing may be adjustable
f) May use any valves (no titanium), but they may be no larger than stock valves.
g) Head may be resurfaced
h) Any head gasket may be used
a) Any piston, piston rings, and wrist pin, may be used, must be within cc limit specified under bore 6. Bottom End
b) After market coatings are allowed on pistons only.
a) No machining to remove weight from the crank (no after-market cranks) (no lightweight cranks)7. Clutch/Transmission
b) The stock unmodified connecting rods must be used (no after-market rods)
c) Aftermarket rod bolts may be used
d) Modifications to oil pump system, oil pick up and oil passages are allowed
e) No dry sump systems are allowed unless it comes from the motorcycle manufacturer as original
a) The clutch does not need to remain stock, but must remain operable8. Ignition
b) Transmission gears must be stock, no close-ratio gears or nonstandard gear-ratios
c) All gears must remain in transmission, no removing any gears. No lightweight or modified stock
a) Stock Rev Limiter must remain intact at all times (ex: no switched or gear specific limiters).9. Induction system
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. 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) Stock appearing ignition must be used (no after-market ignition systems, factory race ignitions are
ok) may use different year ignitions from same manufacturer as long as stock rev limit of engine (not
ignition) is retained.
d) No aftermarket coils
e) Engines that came with stock fuel injection may use an after-market add on components
(example: Power Commander, Dim Sport) to adjust the fuel curve and/or timing (essentially the same
as adjusting jetting and using an ignition advancer).
f) Ignition advancers may be used
g) 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.
h) No traction control device.
i) Only one ECU box present in or on car.
j) A 350 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
a) No mechanically forced induction (turbo charging, supercharging)10. Exhaust
b) Any carburetors may be used on any engine, regardless of year of engine.
c) If the engine did not come from the factory with fuel injection, fuel injection may not be used.
d) If the engine came with factory fuel injection, the fuel injection may be used and may be converted
for use with alcohol. The stock fuel injection throttle bodies must remain, but may be modified for use
with alcohol. Any number of injectors may be used regardless of stock number of injectors.
a) Any exhaust may be used, as long as there is a muffler included with the system that will keep 11. Charging system
noise levels within individual track limits.
a) The stock original factory charging system may not be removed, and must remain in complete 12. Self Starting
working order. No factory racing charging systems.
b) Flywheels can be modified.
a) The engine must self-start at the beginning of the event. If it does not self-start, the car may be 13. Fuel
pushed off and must start at the rear of the event as the penalty.
a) Only alcohol, gasoline, and/or top lube may be used. Non flammable top lube only, no exotic fuel 14. Minimum weight
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.
a) Minimum weight at all times is 775 pounds, car and driver. If weight is added it must be firmly CLARIFICATIONS
bolted in place.
U6SA Page 2 of 2 Issue Date: 10/10/2009
These decisions are made by the U6SA clarification committee, Glen Lewis (head), Kenny Miller, Randy
Brookens, and Rick Stief. You can email claification requests to Glen Lewis Lewis.firstname.lastname@example.org
1. Valve spring spacers are allowed to be used. Generally these are added to increase valve seat
2. Valve guides cannot be replaced with after market valve guides. Although the stock ones can be
modified, you must start with a stock guide.
3. Valve guides may have a 7 angle grind or any grind on them, the stock dimension rule on valve
seats applies to the thickness of the seat, not the grind.
4. Mechanical injection is legal on an engine that came with electronic fuel injection. All other rules
still apply to that system, ie: "Stock appearing ignition must be used" , and "The stock fuel injection
throttle bodies must remain".
Engine Model Year Rev Limit Tach Wire Color
ZX-6RR 03-04 14,400 Light/Blue
ZX-6RR 05-06 14,800 Light/Blue
**Kawasaki ZX-6R 07 15,000 Light/Blue
Yamaha R6 03-05 15,500 Yellow/Black
Yamaha R6S 06-07 15,500 Yellow/Black same engine as 03-05 R6
**Yamaha R6 06-07 16,000 Yellow/Black
Suzuki GSXR 04-05 14,600 Yellow/Blue
**Suzuki GSXR 06-07 15,000 Yellow/Blue
Honda CBR F1-F3 90-98 13,200 Yellow/Green
Honda CBR F4 99-04 13,900 Yellow/Green
Honda CBR RR 05-06 15,000 Yellow/Green
**Honda CBR RR 07 15,500 Yellow/Green
**= Must be 600cc