Wossner Piston Kit 66.36mm Yamaha YZ250 1999-2020 8217DB

If you're running a YZ250 that sees serious track time, piston wear is inevitable—and it directly impacts combustion efficiency, throttle response, and engine longevity. This Wossner kit delivers OEM-quality engineering with measurable gains in reliability and consistent power delivery across the entire RPM range. A complete piston assembly swap eliminates the guesswork and ensures your engine breathes and performs at peak capability.

The aerospace-grade aluminum construction resists deformation under the extreme thermal cycling of 2-stroke operation, while the permanent skirt coating reduces friction and mechanical noise without compromising structural integrity. Every component—piston, rings, wrist pin, and clips—is precision-engineered to work as a unified system, maintaining tight tolerances that newer pistons demand for optimal ring seal and combustion pressure.

• Bore diameter: 66.36mm
• Material: Aerospace-grade aluminum
• Skirt coating: Permanent friction-reduction
• Engine application: YZ250 1999–2020
• Kit contents: Complete assembly
• Piston, rings, pin, clips: Included
• Fitment: Model-specific (YZ250)
• Installation: Requires engine disassembly
• Manufacturer: Wossner
• Part number: 8217DB