JR. PRO STOCK

Flat Kart Only

Weight: 300 lbs. 


  

  • Single cylinder OHV engines only. Clone or Predator 212.
  • Stock engine with a maximum displacement of 212cc.
  • Stock engine with a minimum combustion chamber of 26cc. To be checked with a CC nut.
  • Stock cylinder head is required. No porting or polishing of the Intake/Exhaust runners. No visual alterations may be performed in the runners, bowl area,  or around the valve guide. All head gaskets are legal.
  • Stock crankshaft unaltered, 2.165” maximum stroke.
  • Unaltered SFI-approved flywheel required.
  • Any length connecting rod is legal. Billet aluminum is legal.
  • Stock unaltered piston only (2.766” maximum).
  • Stock camshaft cores only, ez-spin assembly must remain as stock. Max intake lift on cam .225"-min .215" lift taken at push rod. Max intake lift at the valve (.261" for Hemi/ .236" for Wedge Head) taken on the valve spring retainer with zero lash. Max exhaust lift on the cam .232"-min .222" lift taken at pushrod. Max exhaust lift at the valve (.267" for Hemi/ .243" for Wedge Head) taken on the valve spring retainer with zero lash.
  • Stock rocker arms unaltered (Non-Hemi 1:1 ratio max, Hemi 1:1.1 ratio max).
  • Stock lifters unaltered.
  • Any push rods are legal.
  • Stock valves and valve size for the make/model of the head. Stainless replacements OK but must remain stock size for that head. Reaming Valve guide to accept stainless valves also permitted.
  • Valve Spring Installed Height Minimum .815 Maximum Spring Tension of 10.8 at a Height of .850 Max Wire Diameter Of .071”.
  • Any retainers and keepers legal.
  • Stock valve cover unaltered (You may install fuel pump port).
  • Stock side cover unaltered. Pulse fitting OK.
  • Any ignition coil is legal (wire and boot non-tech item).
  • Exhaust:  Any header (Must not extend past the rear bumper).
  • Any Clutch.
  • Stock appearing clone carburetor measuring a maximum .615 at the Venturi and .751” at the exit (Measured with ‘NO-GO’ gauge at the entry of the runner, plus a roundness check of venturi. Venturi must be round. No odd shapes. (i.e. egg or ‘D’ shape). Choke may be removed. Any attempt to draw air past carb will be disqualified.
  • Pump gas only baseline designated by track.
  • Any air filter and/or adapter is legal.
  • Aftermarket carburetor spacers and insulators are illegal.
  • Electric starter and pull starters are legal.
  • Removal of governor and/or governor components is legal (Plugging holes legal).
  • Removal of oil sensor and/or oil sensor components is legal (Plugging holes legal).
  • Flat kart bodies only.