Wossner 79mm Bore Piston Kit (PN# 8559D200) is designed for Yamaha YZ250F and WF250F models from 2001 to 2004. This forged piston offers superior strength and heat transfer efficiency, ensuring optimal performance and durability. Its elliptical design provides a uniform bearing surface under heat expansion, reducing localized pressure and distributing thrust loads evenly to prevent piston collapse. Manufactured in Germany, this piston meets OEM compression standards.

Features

• High-strength forged piston for durability and performance


• Optimized heat transfer to cylinder walls


• Elliptical design prevents piston collapse and ensures even load distribution


• Manufactured in Germany

Specifications

• Bore: 79mm


• Actual diameter: 78.96mm


• Display (cm³): 249


• Stroke (mm): 53.6


• Clearance (mm): 0.04


• Compression Ratio: OEM


• OEM Compression Ratio: 12.50:1


• Dome Volume (cm³): -4.70


• Compression Height (mm): 22.20


• Includes 3 piston rings

Cross-Reference OEM Part Numbers

• Lock: CW16


• Pin: WP059


• Ring Set: 790XAS-2

Vehicle Fitments

• Yamaha YZ250F (2001-2004)


• Yamaha WF250F (2001-2004)