Wiseco PK1588 GP Series 47.5mm Top End Piston Kit for 2003-2007 Honda CR85R

The Wiseco PK1588 is a complete GP Series top end piston kit designed for the 2003–2007 Honda CR85R 2-stroke dirt bike. Built around a 47.5mm (standard bore) forged piston, this kit provides everything needed for a full top end rebuild or an overbore restoration, with no additional components required.

Key Features:

• GP Series forged piston — engineered and forged in-house at Wiseco's Mentor, Ohio facility for superior strength and optimized weight
• Standard 47.5mm bore size — matches OEM cylinder dimensions for direct replacement or stock-bore rebuilds
• Aerospace-grade alloy wrist pin — delivers an exceptional strength-to-weight ratio for high-RPM 2-stroke applications
• High-performance piston ring(s) — precision-matched to the Wiseco piston for proper seal and maximum power retention
• Circlips included — retains the wrist pin securely during assembly
• Complete top end gasket set included — all gaskets needed to seal the top end upon reassembly
• Dedicated forging design optimized specifically for the CR85R engine
• Race-proven construction used by top motocross and supercross teams worldwide

Kit Includes: Forged piston, piston ring(s), wrist pin, circlips, and top end gasket set.

Wiseco is the only U.S. aftermarket piston manufacturer that produces all pistons exclusively using the forging process. Forgings offer condensed, aligned grain structure that provides superior mechanical properties, impact resistance, and fatigue life compared to cast alternatives — critical for the extreme demands of 2-stroke racing engines. In-house dyno testing and 3D finite element modeling ensure each piston design delivers peak performance and longevity.

Note: Wiseco piston rings are application-specific and are not interchangeable with other ring types. Always use the rings supplied with this kit.