Rules
Motors will be inspected throughout the season as necessary. Refusing inspection deems the motor illegal. If a motor is found illegal, the kart is fined, and loses all points and money earned for the day. Fines must be paid before re-entry to the track is allowed. The track reserves the right to inspect any motor at any time. Be honest racers, don’t cheat. You only cheat yourselves. If it doesn’t say you can then you can’t.
IF YOU HAVE ANY QUESTIONS, CALL!
Beginner Box Stock motor rules:
-You must race the motor you qualify with. If you must change a motor after qualifying, you need official’s approval
Motor:
-Factory stock Briggs and Stratton 5hp flat head motor, 13000 series
-Steel or aluminum bore blocks allowed
-Single or dual bearing blocks allowed
-Top of block can’t be modified other than minor deck surfacing
-Eyebrows can be slightly modified and blended
-No aftermarket blocks
-Block may not be machined on intake or exhaust ports gasket mating surface
Stroke:
-Must be stock stroke, is 2.4370”, plus .010” or minus .010” for wear, meaning it must be within 2.4270” to 2.4470”
Valves:
-Stock size valves, 1.115” intake, .990” exhaust, no titanium allowed
-Single angle valve jobs only, intake 30 degrees, exhaust 45 degrees
-No modifying or knife-edging of the valves
-Aftermarket lifters can be used, no titanium allowed
Bore:
-Overbore of .040” over stock 2.5625” size allowed, meaning maximum bore is 2.6025” and can hone up to maximum of 2.6080”
-Regular ferrous sleeves only, with no coatings or plating, such as nica-sil allowed
Crankshaft:
-Stock crankshaft with 1” crankpin required
-No modifying crankshaft, other than hardening
-No lightening, balancing, grinding, offset, or twisted crankshafts
Head:
-Stock Briggs and Stratton heads only
-No welding or filling of head
-Head gasket surface can be machined flat to combustion chamber surface
-Spark plug must be in stock location
-Machining of “fire slot” allowed in head, 1/2" width by 1” length, no relieving for valves or other machining
-Combustion chamber and valve area must be as cast from Briggs and Stratton
-Head guideline specs: spark plug area .419” max, in the area above valves opposite cylinder bore area .311” max
-Any carbon build up will be considered part of the head
-Can run any stock configuration head gasket, copper is allowed, only one allowed
Cam:
-Can run any profile cast iron cam, no billets allowed
-Can run any valve spring combination
Rod and Piston:
-Any rod and piston combination is allowed
Carburetor:
-Bore of .695” No-Go, on carburetor through entire length mandatory
-The carb bore is from the recess on the flange end (end that bolts to block) of the carb to the backside of the throttle shaft
-Diameter of carb recess from flange to throttle bore is .750” maximum No-Go for entire length, and must remain stock length as cast
-Diaphragm side cannot be used to create a pressure fuel feed, diaphragm side of carburetor parts must be installed as supplied from the factory, diaphragm cover plate may be surfaced to ensure a proper seal
-Can machine or polish air horn on carburetor, maximum dimension is 1.011” No-Go, No-Go area is machined area at or below breather hole
-No drilling of any holes anywhere in carburetor, unless specified
-Throttle shaft and butterfly can be modified
-No gun drilled or modified carburetor bolts
-No modifying intake gaskets, must be stock style Briggs and Stratton
-Any attempt to bypass intake gasket, bolts, or bolt holes is prohibited
-Any air filter and air filter adapter is allowed
-Main metering hole: .062” No-Go, Idle hole: .028” No-Go
-No fuel tank modifications allowed
Ports:
-Porting is allowed, intake port .880” No-Go, exhaust port 1.005” No-Go
-No holes in ports allowed
-Dimpling is allowed, if port is pin punched it may not be done in a manner to prevent entry of No-Go in port
Clutch:
-Any swing shoe or disc clutch is allowed, no oil filled
-All motors must have chain guard
Fuel and Oil:
-Fuel must be gas, no methanol
-No oxygenated fuels or nitro additives, you will be tested
-Any oil allowed but no additives such as nitro
-Gas cap must have breather hose, pointing down, extending past tank
Exhaust:
-Any exhaust pipe with muffler is allowed
-Pipe with muffler mandatory, must extend past gas tank
-Muffler must be an RLV type, with at least three baffles
-Must meet 96 decibels
Restrictor Plate:
-Purple Horstman restrictor plate is mandatory, .425” size No-Go, unmodified, non-tapered, with all anodizing intact
-Only one mounting hole can be slotted for easier removal
-No cones or air directing devices can be used
Flywheel:
-Steel Briggs and Stratton 5hp flywheel mandatory
-No balancing or lightening of flywheel, 6lbs 6oz minimum, 6-3/4” minimum across
-Must have all fins on flywheel
-Offset keyways allowed
-Can run any stock appearing stock, configuration coil
Tire:
-SS 55 tire required on right rear, no tire softener
-Must durometer minimum of 50
Box Stock motor rules:
-You must race the motor you qualify with. If you must change a motor after qualifying, you need official’s approval
Motor:
-Factory stock Briggs and Stratton 5hp flat head motor, 13000 series
-Steel or aluminum bore blocks allowed
-Single or dual bearing blocks allowed
-Top of block can’t be modified other than minor deck surfacing
-Eyebrows can be slightly modified and blended
-No aftermarket blocks
-Block may not be machined on intake or exhaust ports gasket mating surface
Stroke:
-Must be stock stroke, is 2.4370”, plus .010” or minus .010” for wear, meaning it must be within 2.4270” to 2.4470”
Valves:
-Stock size valves, 1.115” intake, .990” exhaust, no titanium allowed
-Single angle valve jobs only, intake 30 degrees, exhaust 45 degrees
-No modifying or knife-edging of the valves
-Aftermarket lifters can be used, no titanium allowed
Bore:
-Over bore of .040” over stock 2.5625” size allowed, meaning maximum bore is 2.6025” and can hone up to maximum of 2.6080”
-Regular ferrous sleeves only, with no coatings or plating, such as nica-sil allowed
Crankshaft:
-Stock crankshaft with 1” crankpin required
-No modifying crankshaft other than hardening
-No lightening, balancing, grinding, offset, or twisted crankshafts
Head:
-Stock Briggs and Stratton heads only
-No welding or filling of head
-Head gasket surface can be machined flat to combustion chamber surface
-Spark plug must be in stock location
-Machining of “fire slot” allowed in head, 1/2" width by 1” length, no relieving for valves or other machining
-Combustion chamber and valve area must be as cast from Briggs and Stratton
-Head guideline specs: spark plug area .419" max, in the area above valves opposite cylinder bore area .311” max
-Any carbon build up will be considered part of the head
-Can run any stock configuration head gasket, copper is allowed, only one allowed
Cam:
-Can run any cast iron cam, no billets allowed
-Can run any valve spring combination
Rod and Piston:
-Any rod and piston combination is allowed
Carburetor:
-Bore of .695” No-Go, on carburetor through entire length mandatory
-The carb bore is from the recess on the flange end (end that bolts to block) of the carb to the backside of the throttle shaft
-Diameter of carb recess from flange to throttle bore is .750” maximum No-Go for entire length, and must remain stock length as cast
-Diaphragm side cannot be used to create a pressure fuel feed, diaphragm side of carburetor parts must be installed as supplied from the factory, diaphragm cover plate may be surfaced to ensure a proper seal
-Can machine or polish air horn on carburetor, maximum dimension is 1.011” No-Go, No-Go area is machined area at or below breather hole
-No drilling of any holes anywhere in carburetor, unless specified
-Throttle shaft and butterfly can be modified
-No gun drilled or modified carburetor bolts
-No modifying intake gaskets, must be stock style Briggs and Stratton
-Any attempt to bypass intake gasket, bolts, or bolt holes is prohibited
-Any air filter and air filter adapter is allowed
-Main metering hole: .062 No-Go, Idle hole: .028 No-Go
-No fuel tank modifications allowed
Ports:
-Porting is allowed, intake port .880” No-Go, exhaust port 1.005” No-Go
-No holes in ports allowed
-Dimpling is allowed, if port is pin punched it may not be done in a manner to prevent entry of No-Go in port
Clutch:
-Any swing shoe or disc clutch is allowed, no oil filled
-All motors must have chain guard
Fuel and Oil:
-Fuel must be gas, no methanol
-No oxygenated fuels or nitro additives, you will be tested
-Any oil allowed but no additives such as nitro
-Gas cap must have breather hose, pointing down, extending past tank
Exhaust:
-Any exhaust pipe with muffler is allowed
-Pipe with muffler mandatory, must extend past gas tank
-Muffler must be an RLV type, with at least three baffles
-Must meet 96 decibels
Flywheel:
-Flywheel can be steel Briggs and Stratton 5hp or 3hp, or aluminum 5hp aftermarket
-No balancing or lightening of flywheel
-Must have all fins on flywheel
-Offset keyways allowed
-Can run any stock appearing, stock configuration coil
Tire:
-SS 55 tire required on right rear, no tire softener
-Must durometer minimum of 50
125/250 rules:
-Two stroke 125cc or four stroke 250cc
-Must run the stock cylinder for the motor, no aftermarket cylinders
-Must run the stock head for the motor, no aftermarket heads
-No big bores or strokers allowed
-No oxygenated fuel or additives, you will be tested
-Fuel must be gas, no methanol
-Must have muffler at all times and meet 96 decibels
-QRC 55 tire required on right rear, no tire softener
-Tire must durometer minimum of 50
Open Comp rules:
-Single cylinder
-No big street type motors
-Can’t exceed 600cc
-Two stroke 250cc motors must race with open comp
-No oxygenated fuel or additives, you will be tested
-Fuel must be gas, no methanol
-Must have muffler at all times and meet 96 decibels
-QRC 55 tire required on right rear, no tire softener
-Tire must durometer minimum of 50
2010 Updates
-Weight rule in the 250's is 350lbs
-The Subarus will be teched and held to similar standards as Red Bluff, etc.
-Beginner Subarus will run with Beginner Box Stock for no points, no money; Box Stock Subarus will run will Box Stock class, must be sealed, and are subject to tech
-We are heading towards the direction of the Subaru motor for season 2011. The remaining flat heads will still be allowed to run, but on the gold restrictor plate in Box Stock, purple restrictor plate in Beginner Box Stock. We understand that some already have the Subaru motors and others will need to buy them at some point. We will be offering these motors at a lower cost to help. $875 for the Box Stock motor and $775 for the Beginner Box Stock motor, or get them through QRC or a dealer such as MBS, B+S Machine, etc.
-Once you race five races in a certain class at any track before the start of the season, you are no longer considered a rookie
Beginner Box Motor Rules (not relevant yet)
Sealed Subaru with proper restrictor.
Subaru EX27 with a special crank snout / exhaust system plus a restrictor plate
Sealed motors may only be rebuilt by licensed dealers and then resealed
NOTE: Dealers will be responsible for motor being legal
You are responsible to make sure official seal is attached and untampered with
Must have stock timing. No Key or Keyway Modifications
Factory spec valve springs only (will be subject to tech)
Box Stock Motor Rules (Subaru)
Sealed Subaru motor only
Sealed motors may only be rebuilt by licensed dealers and then resealed
NOTE: Dealers will be responsible for motor being legal
You are responsible to make sure official seal is attached and untampered with
Must have stock timing. No Key or Keyway Modifications
Factory spec valve springs only (will be subject to tech)
Dealer responsible for sealed motor
Owner/driver responsible for non seal issues
2009 Updates
-Must race 70% of the races to be eligible for a trophy at the end of the year
-Transponders must be mounted on the steering support directly in front of the seat
-Weight rule
Beginner Box Stock 165lbs (kart only)Box Stock 250lbs125/250 320lbs500400lbs-Subarus will only be allowed to run with Box Stocks. This is on a trial basis
-Box stock rule changes
Head depths WILL BE DEPTH CHECKEDsquish (above piston) .000 minvalve side.311 maxspark plug area .419 max-250 motors ARE SUBJECT TO TECH, WILL BE CC'd AND/OR TORN DOWN. NO BIG BORES, NO STROKERS
