Wossner 8216DB Piston Kit - 1999-2026 Yamaha YZ250 / YZ250X Size B

Wossner 8216DB Premium Forged 2-Stroke Piston Kit - Size B

Keep your Yamaha 2-stroke running at peak potential with the Wossner 8216DB Piston Kit. Specifically engineered for the Yamaha YZ250 and the cross-country YZ250X, this Size B forged kit is the professional choice for restoring Factory Quality power in seasoned cylinders. At Moto-House MX, we know the YZ250 is a legend of reliability and performance; Wossner’s aerospace-grade forged components provide the extra durability needed for competitive motocross and grueling off-road racing.

Forged from aerospace-grade aluminum alloy, this piston offers superior structural integrity and heat resistance compared to standard cast alternatives. The 8216DB features a permanent skirt coating to minimize friction and piston rock, ensuring a quieter engine and smoother throttle response. This Size B piston (66.36mm) is precision-matched for cylinders with a 66.41mm bore, providing the exact clearances required for optimal compression and power delivery in used cylinders.

Top Features: Wossner 8216DB Piston Kit

• Standard Size B (66.36mm): Precision-engineered for 66.41mm bores to maintain perfect factory-spec tolerances in used cylinders.
• Aerospace Forged Alloy: High-strength aluminum construction built to withstand the mechanical stress of high-RPM 2-stroke racing.
• Low-Friction Skirt Coating: Permanent coating reduces wear on the cylinder walls and provides a quieter engine operation.
• Dual-Ring Design: Optimized for a consistent combustion seal and improved heat transfer for sustained power throughout your ride.
• Complete Assembly: Kit includes the forged piston, high-quality rings, wrist pin, and clips.

Expert Pro-Tip: The Yamaha YZ250 engine is a masterpiece of design, but even the best Nikasil cylinders experience microscopic wear over time. Size B is the ideal choice for a mid-life engine refresh, as it compensates for that wear to prevent piston slap and maintain maximum compression. When rebuilding, always inspect your power valve for carbon buildup and replace your small-end bearing to ensure a professional-grade top-end service.

Fitment List

Year Range	Vehicle Brand	Vehicle Model
1999-2026	Yamaha	YZ250
2016-2026	Yamaha	YZ250X

Frequently Asked Questions

Q: What is the difference between Size A and Size B?
A: Size B (66.36mm) is exactly 0.01mm larger than Size A. This slight increase allows you to maintain the factory-specified piston-to-wall clearance as the cylinder wall experiences natural wear over time, preventing power loss and ensuring a quieter engine.

Q: Does this fit the YZ250X woods model?
A: Yes, the YZ250X uses the same bore and piston configuration as the YZ250 motocross model, making this kit a perfect fit for both machines.

Q: Does this kit include the wrist pin bearing?
A: No, the kit includes the piston, rings, pin, and clips. We highly recommend purchasing a new small-end bearing separately for every top-end rebuild to prevent premature failure.

Recommended Pairings

• Top End Gasket Kit: Essential for a professional, leak-free engine rebuild with a fresh set of gaskets.
• Motorex Cross Power 2T Oil: Premium synthetic protection specifically formulated for high-performance 250cc 2-strokes.

Restore your machine’s power and precision today. Buy now at Moto-House MX!

Moto-House MX – Choice of Champions – is located in Clermont/Montverde, FL. The Best Motocross/UTV & ATV Shop in Central Florida. Stop by our local store in Montverde, FL or enjoy lightning-fast shipping across the USA.