Rules

2012-2014 600cc U6SA Engine Rules

U6SA Page Issue Date: 8/30/2010

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 deporting of intake or exhaust runners.
i) Valve jobs, valve grinding, valve seating, valve seal modification and valve seat cutting are
allowed.
ii) 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) OEM Head only.
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 aluminum connecting rods.
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.
b) Clutch must remain operational
c) No modification to the stock transmission gears, no close-ratio gears or nonstandard gear-ratios.
All gears must remain in transmission, no removing any gears.
7) Ignition
a) No aftermarket ECU’s, stock appearing ECU only. Reflashing of ECU and factory race ECU’s are
allowed. Stock factory rev limit must remain in place for all engines larger than 600cc. 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). If a computer is hooked up to
check the ECU it must be set to U6SA specified rpm’s, 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.
d) No aftermarket coils

2012-2014 600cc U6SA Engine Rules

U6SA Issue Date: 8/30/2010