WOSSNER 77mm PISTON KIT B, YAMAHA YZ250F 14-15, WR250F 15-17, YZ250FX 15-16

This Wossner forged piston kit, part number 8893DB, features a 77.01mm bore with an actual piston size of 76.97mm (+0.01mm oversize). Designed for TM MX-F450 (2009–2010), MX-Fi450 (2011), and EN-Fi450 (2011) models, it delivers high-performance characteristics through its forged construction and elliptical profile, ensuring strength, heat efficiency, and balanced load distribution under expansion. Manufactured in Germany, this piston is suitable for racing and performance applications.

Features

• Forged construction for enhanced durability and strength
• Elliptical design promotes even expansion and load distribution
• Engineered for efficient heat dissipation
• Made in Germany
• Direct OEM replacement
• Easy to install; professional installation recommended if unsure

Specifications

• Bore Size: 77.01mm
• Actual Piston Size: 76.97mm
• Displacement: 249cm³
• Stroke: 53.60mm
• Clearance: 0.05mm
• Dome Volume: -3.00cm³
• Wossner Compression Ratio: 13.70:1
• OEM Compression Ratio: 13.50:1
• Compression Height: 20.20mm

Cross-Reference OEM Part Numbers

• 40116M07700
• CW16 (Lock)
• WP087 (Pin)
• 770XAS-2 (Ring Set)

Vehicle Fitments

• TM MX-F450 (2009–2010)
• TM MX-Fi450 (2011)
• TM EN-Fi450 (2011)