Wossner forged piston kit with a 77.02mm bore and 76.98mm diameter, designed for Yamaha YZ250F and WR250F models. This 2-ring piston is engineered for high performance, featuring superior strength and design. Manufactured in Germany, it ensures optimal heat transfer to cylinder walls. Its elliptical design provides a uniform bearing surface under heat expansion, reducing localized pressure and evenly distributing thrust loads to prevent piston collapse.

Features

• Forged construction for superior strength


• Optimized heat transfer for efficient combustion


• Elliptical design for uniform load distribution


• 2-ring piston design for performance applications


• Increased compression ratio for improved power output


• Manufactured in Germany

Specifications

• Bore: 77.02mm


• Diameter: 76.98mm


• Display (cm³): 249


• Stroke (mm): 53.60


• Clearance (mm): 0.04


• Wossner Compression Ratio: 14.10:1


• OEM Compression Ratio: 13.50:1


• Dome Volume (cm³): -5.00


• Compression Height (mm): 22.50

Cross-Reference OEM Part Numbers

• Wossner Piston Yamaha YZ250F (PN# 8713DC)


• Lock P/N: CW16


• Pin P/N: WP059


• Ring Set P/N: 770XAS


• Rod P/N: P4005

Vehicle Fitments

• Yamaha YZ250F (2008-2013)


• Yamaha WR250F (2008-2013)