Wiseco PK1161 2-Stroke Piston Kit 41.0mm Yamaha PW50 Top End Rebuild

The Wiseco PK1161 is a complete 2-stroke top-end piston kit engineered specifically for the Yamaha PW50 (through 2009) at a 41.0mm (653M) bore size. Designed for overboring or full top-end rebuilds, this kit delivers the strength and precision Wiseco is known for — all engineered, forged, and machined in the USA in Mentor, OH.

Kit Includes:

• Forged piston (41.0mm bore)
• Piston ring(s)
• Wrist pin
• Circlips
• Top-end wrist pin bearing
• Top-end gasket kit

Key Features:

• Forged from high-silicon aluminum alloy for maximum strength and dependability
• Dedicated forgings with additional lightening operations provide an optimized strength-to-weight ratio
• Improved tensile strength of forged material extends service life over cast alternatives
• Designed and built specifically for the Yamaha PW50 2-stroke engine — not a universal fit
• Race-proven design trusted by top teams in Supercross, Motocross, and GNCC competition
• Everything needed to complete a top-end rebuild in a single kit

Wiseco's legacy in 2-stroke piston manufacturing spans over 80 years, dating back to 1941. Unlike cast pistons, Wiseco forgings feature a condensed, aligned grain structure that delivers superior mechanical properties, impact resistance, and fatigue resistance — critical qualities for high-revving 2-stroke engines. Note: Cylinder sleeve must be purchased separately.