Wossner 8957DB 76.97mm Piston Kit 14.0:1 2019-2025 Yamaha YZ250F/FX WR250F

Restore peak power and precision to your engine with the Wossner 8957DB Premium Series Piston Kit. Specifically engineered for high-performance Yamaha 250cc four-strokes, this Size B (76.97mm) piston is the ideal choice for riders looking for a tighter fit in a slightly worn cylinder to maintain maximum compression. At Moto-House MX, we understand that Racing Performance depends on exact tolerances, and this forged aluminum alloy piston delivers the durability required for professional motocross competition.

The Wossner 8957DB features a double-bridge forging design and a 3D crown to withstand the high-heat environments of modern racing. This kit is optimized with a 14.0:1 compression ratio, providing an immediate boost in throttle response and low-end torque. Designed with skirt coatings for reduced friction, this piston ensures a smoother engine break-in period while the enhanced piston pin oiling slots provide critical lubrication to the wrist pin under extreme RPMs.

Top Features: Wossner 8957DB Piston Kit

• Double Bridge Forging: High-strength, lightweight forged construction for superior structural integrity.
• 14.0:1 Compression Ratio: Delivers elite 4-stroke power gains and optimized combustion.
• Size B (76.97mm): Designed for precision piston-to-wall clearance to ensure a quieter, more efficient engine.
• Advanced Skirt Coating: Reduces parasitic drag and provides improved wear resistance.
• Complete Top-End Kit: Includes the 76.97mm piston, high-performance rings, wrist pin, and clips for a total OEM replacement upgrade.

Fitment List

Year Range	Vehicle Brand	Vehicle Model & Size
2019-2025	Yamaha	YZ250F
2020-2025	Yamaha	YZ250FX
2020-2025	Yamaha	WR250F

Frequently Asked Questions

What is the difference between Size A and Size B pistons?
Size B (76.97mm) is slightly larger than Size A. It is used to maintain a tight piston-to-wall clearance as the cylinder bore naturally wears, ensuring better ring seal and oil control.

Does this kit include everything needed for a top-end rebuild?
Yes, this is a complete piston kit including the forged piston, high-tension rings, wrist pin, and retaining clips.

Is the 14.0:1 compression ratio safe for pump gas?
This ratio is designed for high-performance racing; while it may run on high-quality pump premium, many racers prefer a race-gas blend to maximize the performance gains and prevent detonation.

Upgrade Your Ride with the industry's leading forging technology. Buy the Wossner 8957DB Piston Kit today from Moto-House MX.

Moto-House MX – Choice of Champions – is located in Clermont/Montverde, FL. The best motocross shop in Central Florida.