KB Performance motorcycle pistons are offered in Cast Hypereutectic 390 alloy and Forged 4032 low expansion alloy. In addition to greater thermal properties, Hypereutectic alloys have 16% silicon which gives superior wear properties. The low thermal conductivity of this alloy requires engines running hypereutectic pistons to reduce total ignition timing 2 to 4 degrees.

Forged 4032 Alloy is an 11% silicon alloy that is formed in a forging press then fully machined. The combination of this alloy and forging process allows the piston to flex under detonation or pre-ignition, giving the best resistance to cracking. Since 4032 alloy has a low expansion rate but higher than Hypereutectic, it will require about a
.001” wider piston to wall clearance. Forged pistons are suited for Street or Race with power adders such as NOS or
boost. Models that end in a “C” come with Anti-Friction skirt coating.