PISTON KIT 77-78 YZ400 86.00, WOSSNER 8264D100 YAMAHA MX, 77-78 IT400

This Wossner piston kit features an 86mm bore size (85.92mm actual) and is designed for Yamaha YZ400 and IT425 models from 1977 to 1978. Forged in Germany, the piston is engineered for optimal strength and heat management. Its elliptical profile distributes thrust loads uniformly during thermal expansion, reducing localised pressure and minimising the risk of piston collapse.

Features

• Forged construction for enhanced structural integrity

• Elliptical design ensures uniform load distribution under heat expansion

• Promotes efficient heat transfer from combustion chamber to cylinder walls

• Manufactured in Germany

Specifications

• Bore Size: 86mm (85.92mm)

• 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: 8264D100

• Lock: CW18

• Pin: WP042

• Ring Set: RSC8600 x2

• Part No.: 56-W550_1.00.WO

Vehicle Fitments

• Yamaha YZ400 1977

• Yamaha YZ400 1978

• Yamaha IT425 1977

• Yamaha IT425 1978