Piston Kit 87-09 YFZ350 66.50, Wossner 8075D250 Yamaha ATV

This Wossner forged piston kit features a 66.50mm bore size and is designed for high-performance applications in a range of Yamaha two-stroke engines. Engineered in Germany, the piston ensures optimised heat transfer, structural integrity, and uniform bearing surface through its elliptical design. It is suited for applications where durability and precision are required. This kit includes a +2.50 oversize piston and is compatible with multiple Yamaha models spanning decades of production.

Features

• Forged construction for improved strength and durability

• Elliptical design distributes thrust loads evenly to prevent piston collapse

• Enhanced heat transfer from combustion chamber to cylinder walls

• Made in Germany

• Includes piston, pin, locks, and ring set

Specifications

• Bore Size: 66.50mm

• Actual Bore: 66.44mm

• Stroke: 54.00mm

• Clearance: 0.06mm

• Compression Ratio (Wossner and OEM): 2-stroke

• Compression Height: 36.00mm

• Displacement: 347 cm³

Cross-Reference OEM Part Numbers

• Piston Kit Part No: 56-W513+250.WO

• Lock P/N: CW16

• Pin P/N: WP027

• Ring Set P/N: RSB6650 (x2)

Vehicle Fitments

• Yamaha YFZ 350 Banshee (1987–2007)

• Yamaha RD350 LC - YPVS (1980–1987)

• Yamaha RD350 AC (1950–2014)

• Yamaha RZ350 (1982–1990)

• Yamaha RD 350 (1973–1976)

• Yamaha RD 400 (1976)