Wiseco WK1041 Forged Piston Kit for 1990-1996 Yamaha WaveRunner SuperJet 650 +0.050" Oversize

The Wiseco WK1041 is a complete top-end forged piston kit engineered for 1990–1996 Yamaha WaveRunner and SuperJet 650cc 2-stroke personal watercraft engines. Designed as a +0.050" oversize replacement at 77.50mm bore, this kit is ideal for engines that have been bored out during a top-end rebuild.

Wiseco pistons are forged from high-silicon, low-expansion aluminum alloy, delivering superior tensile strength, reduced reciprocating weight, and excellent heat transfer compared to cast alternatives. The result is a piston that holds up under the high RPM and thermal demands of a 2-stroke PWC powerplant.

Kit Contents:

• Forged aluminum piston
• Piston rings (Wiseco-matched — not interchangeable with other brands)
• Wrist pin
• Circlips
• Top-end gasket kit

Key Features:

• Forged high-silicon aluminum construction for strength, reduced weight, and improved heat dissipation
• +0.050" oversize bore (77.50mm) — designed for bored or worn cylinders at this spec
• 641cc displacement — matched to the Yamaha 650 2-stroke engine family
• CNC diamond-turned finish for precise sizing and consistent fit across all compatible cylinder bore compositions including cast iron, chrome, Nikasil, and boron composite
• Wiseco rings are matched exclusively to Wiseco pistons — do not substitute with third-party rings

The WK1041 is a trusted choice for recreational riders and performance builders restoring or upgrading the top end of their Yamaha 650 PWC engine.