Wiseco PK1866 Forged Piston Top End Rebuild Kit 96mm 12.5:1 CR

The Wiseco PK1866 is a complete top end rebuild kit designed for the 2009–2012 Honda CRF450R. Built around a 96mm forged piston with a 12.5:1 compression ratio, this kit delivers the durability and performance that Wiseco is renowned for in the motocross and off-road racing community.

Wiseco's forged pistons are manufactured using a cold-forging process that produces a denser, stronger grain structure compared to cast pistons, resulting in superior strength-to-weight ratio and resistance to heat and fatigue under high-performance conditions. The piston features Wiseco's ArmorGlide skirt coating, a low-friction, wear-resistant treatment applied to the piston skirt that reduces friction, minimizes scuffing during break-in, and extends overall engine life.

Kit Includes:

• Forged 96mm piston (overbore) — also referenced as 4978M
• Piston rings
• Wrist pin
• Circlips
• Top end gasket set

Key Specifications:

• Bore Size: 96mm
• Compression Ratio: 12.5:1
• Piston SKU / Size Reference: 4978M
• ArmorGlide low-friction skirt coating
• Designed for overboring or complete top end rebuilds

The Wiseco PK1866 is an ideal choice for riders looking to restore peak engine performance or increase displacement on their CRF450R. All components are precision-matched for a straightforward installation and reliable, race-ready performance.