Stock Head W/ seats and guides 40mm Intake 35.5mm Exhaust

AA 500 Series CastingWith seatsand guides40mm Intake 35.5mm Exhaust, It is set up to build the performance Head of your needs.

The 500Series Castings come STD with: Cleanflowingcooling vanes, formaximumcooling through the head, and around the intake ports forincreasedHP and over all cooling. Amodernized Combustionchamber, for increased head flow & performance. AsecondFull Fin, soyoucanFlycutyourheads deeper to achieve almost any desired Head CC volume needed. Blocked off rocker stud bosses, to eliminate the O-ring and stoppossibleoil leaks. Long reach 3/4 Inch SparkPlugs, toreduce the chance of cracking betweenthe Valve seat and Plug.

Casting: AA 500

Valve Size: N/A

Head Bore: 85.5

Plug Size: 12mm (ReplacementNGK Number is D8EA)