PISTON KIT 05-07 YZF250 77.00, WOSSNER 8612DA 2-RING, 5NL-11631-20-00

Wossner forged piston kit with a 77mm bore, designed for Yamaha WR250F, YZ250F, and Gas Gas EC250F models. This two-ring piston is engineered for optimal combustion chamber heat transfer and uniform bearing surface under heat expansion, reducing localized pressure and piston collapse. Manufactured in Germany for durability and precision.

Features

• Forged piston for superior strength and design
• Two-ring design for performance and durability
• Optimized heat transfer to cylinder walls
• Elliptical design for uniform bearing surface and even thrust load distribution
• Manufactured in Germany

Specifications

• Bore: 77mm
• Standard size piston (PN# 8612DA)
• Lock Part Number: CW16
• Pin Part Number: WP059
• Ring Set Part Number: 770XAS-2
• Displacement: 249 cm³
• Stroke: 53.6mm
• Clearance: 0.04mm
• Wossner Compression Ratio: OEM
• OEM Compression Ratio: 12.50:1
• Dome Volume: -2.80 cm³
• Compression Height: 22.20mm

Cross-Reference OEM Part Numbers

• 5NL-11631-20-00
• 5XC-11631-00-00

Vehicle Fitments

• Yamaha WR250F (2005-2007)
• Yamaha YZ250F (2005-2007)
• Gas Gas EC250F (2010-2015)