
The Story
Wössner forged piston kit with an 85mm 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: 85mm (84.94mm 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
- Compression Height: 26.20mm
- Theoretical Weight: [Not provided]
Cross-Reference OEM Part Numbers
- Wössner Piston: 8604DA
- Lock: CW20
- Pin: WP052
- Ring Set: 850XSY
- Rod: P4021
- OEM Part Numbers: 13110-KCY-670, 4628M08500
Vehicle Fitments
- Honda XR400R (1996-2004)
- Honda TRX400EX (1999-2008)
- Honda TRX400X (2009-2012)

Details & Craftsmanship
Every detail has been carefully considered to bring you the perfect product.

Details & Craftsmanship
Every detail has been carefully considered to bring you the perfect product.

Details & Craftsmanship
Every detail has been carefully considered to bring you the perfect product.
Description
Wössner forged piston kit with an 85mm 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: 85mm (84.94mm 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
- Compression Height: 26.20mm
- Theoretical Weight: [Not provided]
Cross-Reference OEM Part Numbers
- Wössner Piston: 8604DA
- Lock: CW20
- Pin: WP052
- Ring Set: 850XSY
- Rod: P4021
- OEM Part Numbers: 13110-KCY-670, 4628M08500
Vehicle Fitments
- Honda XR400R (1996-2004)
- Honda TRX400EX (1999-2008)
- Honda TRX400X (2009-2012)




















