A CLASS BONUS presented by STINGER RACE FUELS distributed by Groff Motorsports

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**THIS IS NOT REQUIRED to race the event**

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$300 bonus from STINGER RACE FUELS distributed by GROFF MOTORSPORTS to the highest finishing 600 Micro Sprint that is running the A Class Rules posted below (National Open Wheel 600 A Class Rules).

You do not need a separate motor to come to PA and run this race

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WINGS: 10 square ft. max, left sideboard 24” x 48”, right sideboard 18” x 48”, nose wing 18”x 24” max.

Offsets are allowed.

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Nose wings cannot exceed 8 ½” tall or 21” long.

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ENGINE: 600cc 4-cylinder 4 stroke as comes on a stock production bike for public sale in the U.S.A. No current year production engines. Except as noted, all internal and external engine parts must remain stock with no modifications, metal removal, blueprinting. Valve seat inserts may be reworked. Valves must remain as produced with no modifications. Valve springs may be shimmed with standard or aftermarket shims. Cylinder head combustion chambers may be cleaned by bead blasting with valves seated in place. Intake and exhaust ports may not be bead blasted. Cylinder head gaskets may be replaced only with original equipment manufacturer’s stock parts (All 3 layers of the head gasket must be used). All other gaskets may be replaced with duplicate aftermarket parts. Light cleaning of gasket surfaces with steel wool, Scotch-Brite, etc. is allowed.

Transmission gears may be shimmed only for the purpose of proper engagement. Standard or aftermarket shims may be utilized. Aftermarket cam chain tensioner allowed for safety of motor. Fuel injection engines can run carburetors. Fuel injection engines running carburetors may change all fuel metering devices to tune fuel curve. Injection must be OEM, stock OEM throttle bodies no mixing manufacturers (i.e. Suzuki on Suzuki, Yamaha on Yamaha etc.) with OEM Boots in place. Modification of oil pan & pick up allowed or aftermarket ok. Modification to thermostat cover allowed or aftermarket ok. Modification to water pump Cover allowed or aftermarket ok. Any air box, stock appearing CDI, aftermarket washable replacement air filter. Any 600cc OEM CV carburetors (no flat slides allowed).

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REV: u6SA Rev Rule

Rev limit for all 600cc (nothing larger than 600cc) engines is 16,100 rpms. U6SA specified Rev Limit must remain intact at all times (no switched or gear specific limiters).

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TIRE: Spec Right Rear Tire

Hoosier U6SA, NMMA, ASCS2, or KS1

American Racer NMMA or MD57B

Right Rear tire Must durometer 50 before and after race, 5 minute cool down period allowed.