This Wossner piston kit features an 87mm bore size (86.92mm actual) and is designed for Yamaha YZ400 and IT425 models from 1977 to 1978. Manufactured in Germany, the forged piston is engineered for high durability and optimised heat transfer. Its elliptical design supports even load distribution during thermal expansion, reducing localised pressure and preventing piston collapse.

Features

• Forged construction for maximum strength

• Elliptical design distributes thrust loads evenly under expansion

• Engineered for efficient combustion chamber heat transfer

• Made in Germany

Specifications

• Bore Size: 87mm (86.92mm)

• Display: 398 cm³

• Stroke: 82.00 mm

• Clearance: 0.08 mm

• Compression Height: 40.00 mm

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

Cross-Reference OEM Part Numbers

• Piston Kit: 8264D200

• Lock: CW18

• Pin: WP042

• Ring Set: RSC8700 x2

• Part No.: 56-W550_2.00.WO

Vehicle Fitments

• Yamaha YZ400 1977

• Yamaha YZ400 1978

• Yamaha IT425 1977

• Yamaha IT425 1978