Micro Sprint Rules

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2017 Micro Sprint Rules

250/450 SUPERSTOCK CLASS RULES FOR 2016
1) Driver age; driver shall be at least 14 yrs old with no maximum age limit. All drivers running the East Bay races have to be at least 14 yrs old at the time of event.
2) CARS; chassis must be of the microsprint design( 250 or 600 ) no up right or lightning sprint chassis.
3) WINGS ; Wings are allowed with a maximum of 12sq feet and 54″ side boards. Wicker bills are allowed.
4)TIRES: tires are open in sizes and compounds.
5)Fuel: fuel will be pump or race gas. No oxygenated fuels and no performance enhancing additives. No alcohol allowed
6) ENGINE: Will be either ATV or Dirt Bike in origin. Any manufacture. No road race engines allowed.
7) These rules apply to all cars weighing 610 lbs and under 750 lbs. with a minimum weight of 610lbs
A) All engines will be completely stock and unmodified except as specified in the rules. IF IT DOESN’T SAY YOU CAN DO IT THEN YOU CAN’T.
B) No multi cylinder engines
c) Any year or manufacture is allowed.
d) PISTON- 250(2stroke )MOD may run a larger bore piston from stock with a max displacement of 265 cc’s . 450 (4stroke) must run a stock bore size with a 450cc max. Any piston manufacture is allowed
e) Crankshafts; THERE WILL BE NO STROKERS ALLOWED. MUST BE OEM SPEC FOR THE BRAND AND MODEL OF YOUR ENGINE ( BRANDS ALLOWED; Wiseco , Hot Rods or OEM stock cranks) Crankshaft must be steel , no light weight or knife edged rods, no titanium or light weight materials allowed unless used by the factory for balancing. no machining or modifications allowed. any OEM spec specific rod for the year and brand of your engine can be used for rebuilding of the crank.
f) HEADS; 250 MOD can run either a stock head or a cool head design. 450’s must remain stock with stock oem spec valve sizes. After market valves can be run. Heads may be surfaced for flatness and a valve job for refreshing is allowed. No porting of the head..
g) 450 4strokes may run a stage 1 Hot Cam or stock cams. No other manufacture or cam is allowed.
h) 250 Mod’s may run a ported cylinder. the cylinder may be rebuilt with either a sleeve or replating.
j) CLUTCH; 250 mod’s may run a machined or welded clutch. 450’s must have a operating clutch ( to encourage elect start)
k) Oil systems can be modified for durability. No dry sump engines unless it came from the factory.
l) NO CERAMIC BEARINGS IN ENGINE
M) MUFFLERS; Any muffler combination is allowed. Mufflers are mandatory. ALL CARS SUBJECT TO MAXIMUM OF 98 DECIBEL READING AT TRACK SIDE.
8) This is for cars weighing over 750lbs these rules will apply
1) 2 Strokes . Engine can be of any manufacture with a bore and stroke combination not to exceed 270cc. All other 2 stroke rules apply
2) 4 stroke engines may have a max displacement of 520 cc’s max bore size cylinder. NO STROKER CRANKS ALLOWED. May run either a stage 1 Hot Cam or a stage 2 Hot Cam no other manufacture or cam allowed. All other 4 stroke rules still apply


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