PISTON KIT XR400 TRX400 85.50, FORGED WOSSNER 8604D050

Wössner forged piston kit with an 85.50mm bore, designed for Honda XR400R motorcycles and TRX400 series 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: 85.50mm (85.44mm actual)
• Display: 397 cm³
• Stroke: 70.00mm
• Clearance: 0.06mm
• Wössner Compression Ratio: 11.00:1
• OEM Compression Ratio: 10.00:1
• Dome Volume: +3.20 cm³

Cross-Reference OEM Part Numbers

• Wössner Piston: 8604D050
• Lock: CW20
• Pin: WP052
• Ring Set: 855XSY
• Rod: P4021

Vehicle Fitments

• Honda XR400R (1996-2004)
• Honda TRX400EX (1999-2008)
• Honda TRX400X (2009-2012)