WOSSNER 8217DA 1999-2026 Yamaha YZ250 YZ250X 66.35mm Forged 2-Stroke Piston Kit

Ditch the stock cast tolerances and give your YZ250 the forged durability it needs to actually stay together when the gate drops.

If you're serious about your 250cc power plant, you know that cast pistons are the weak link when the RPMs climb. This Wossner Forged Piston Kit is the mechanical solution for the 1999-2026 Yamaha YZ250 and YZ250X, offering a massive leap in structural integrity over standard parts. Forged from aerospace-grade aluminum alloy, this kit is designed to maintain consistent compression and eliminate the "soft" throttle response that comes with worn-out top ends. It delivers Factory Quality fitment that ensures your Yamaha stays crisp through the entire powerband, moto after moto.

The technical advantage here is Wossner’s single-ring design and permanent skirt coating. By reducing internal friction and piston rock, this kit minimizes drag and heat buildup—the two biggest enemies of a high-performance 2-stroke. This isn't just a replacement part; it’s a hardware upgrade that provides a more stable piston path and better ring seal. Whether you’re wide open on a moto track or lugging through the woods on a YZ250X, this forged setup provides the reliability required for riders who don't have time for a DNF.

• Aerospace Forged Alloy: Significantly higher tensile strength than cast pistons to prevent skirt collapse.
• Permanent Skirt Coating: Reduces friction and protects the cylinder bore during high-load operation.
• Precision Single-Ring Design: Engineered for reduced drag and immediate throttle response at high RPM.
• Machined for Strength: Lightened architecture that reinforces critical stress points in the crown and skirt wall.
• Full Rebuild Components: Comes with the 8217DA piston, high-performance ring set, wrist pin, and clips.

Expert Pro-Tip: Don't just slap this in. Measure your ring end gap and check your cylinder bore to ensure the 66.35mm Size A provides the correct clearance. Always perform three progressive heat cycles before you pin it, and never reuse an old needle bearing when installing a forged piston.

Frequently Asked Questions

Is this a direct replacement for the OEM Yamaha piston?
Yes, it is designed to replace the stock piston but offers the added strength of a forged aluminum alloy construction.

What comes in the 8217DA kit?
The kit is complete with the piston (#8217DA), a performance ring set (#RSB6640), wrist pin (#WP033), and heavy-duty retaining clips (#CW18).

Will this work with the YZ250X cross-country model?
Absolutely. This kit is compatible with all 250cc 2-stroke Yamaha engines from 1999 through the 2026 model year, including the X version.

Recommended Pairings:
Cometic Top-End Gasket Set, Yamaha OEM Needle Bearing, and Premium 2-Stroke Pre-mix Oil.

Moto-House MX – Choice of Champions – is located in Clermont/Montverde, FL. We are the best motocross shop in Central Florida with lightning-fast shipping.