WOSSNER 85mm PISTON KIT B, HONDA XR400R 1996-2004, TRX400EX/X 1999-2014

Wössner forged piston kit with an 85.01mm bore, designed for Honda TRX400EX and TRX400X ATVs. Manufactured in Germany, this high-performance piston enhances strength, heat transfer, and durability. The elliptical design ensures uniform bearing surface distribution, reducing localized pressure and preventing piston collapse.

Features

• Forged construction for superior strength and durability
• Optimized heat transfer to cylinder walls
• Elliptical design for uniform bearing surface under heat expansion
• Increased compression ratio for improved engine performance
• Made in Germany

Specifications

• Bore: 85.01mm (84.94mm actual)
• Display: 397 cm³
• Stroke: 70.00mm
• Clearance: 0.06mm
• Wössner Compression Ratio: 12.50:1
• OEM Compression Ratio: 10.00:1
• Dome Volume: +8.40 cm³
• Compression Height: 26.20mm

Cross-Reference OEM Part Numbers

• Wössner Piston: 8702DB
• Lock: CW20
• Pin: WP052
• Ring Set: 850XSY
• Rod: P4021

Vehicle Fitments

• Honda TRX400EX (1999-2008)
• Honda TRX400X (2009-2012)