Wossner 8330DA Piston Kit - 2002-2026 Yamaha YZ85 Standard Size A

Wossner 8330DA Standard Series Forged 2-Stroke Piston Kit - Standard Size A

Keep your young racer at the front of the pack with the Wossner 8330DA Piston Kit. Engineered specifically for the iconic Yamaha YZ85 (2002-2026), this Standard Series forged kit is the professional choice for a high-performance top-end refresh. At Moto-House MX, we know that 85cc mini-cycle engines live at the top of the RPM range; Wossner’s aerospace-grade forged components provide the superior strength and heat management required to keep your YZ85 screaming around the track with confidence.

Forged from premium aluminum alloy, the 8330DA features a dual-ring design. For the YZ85, this configuration offers enhanced heat transfer from the piston to the cylinder wall and provides better low-to-mid range torque stability, which is vital for clearing jumps and accelerating out of corners. Wossner’s optimized machining ensures the piston remains exceptionally lightweight to maintain the YZ's legendary snap, while reinforcing the crown and skirt for professional-grade durability. The permanent skirt coating reduces internal friction and piston rock, ensuring a quieter engine and a more efficient break-in. This Size A piston (47.45mm) is precision-matched for standard 47.50mm bores, making it the perfect choice for a cylinder in excellent condition.

Top Features: Wossner 8330DA Piston Kit

• Standard Size A (47.45mm): Precision-engineered for 47.50mm bores to maintain factory clearances and optimize engine performance.
• Dual Ring Design: Improves sealing and heat dissipation, offering a broader powerband and increased reliability for mini-moto racing.
• Aerospace-Grade Forged Construction: Significantly more durable than stock cast pistons, providing the strength needed for high-RPM 2-stroke competition.
• Low-Friction Skirt Coating: Permanent molybdenum disulphide coating protects the cylinder wall and ensures smooth operation during the break-in phase.
• Optimized Machining: Balanced for lightness and strength to maximize throttle response without sacrificing structural integrity.
• Complete Assembly: Kit includes the forged piston, high-performance rings, wrist pin, and circlips.

Expert Pro-Tip: The Yamaha YZ85 is a bulletproof machine, but consistent top-end maintenance is the secret to winning races. Size A is the ideal choice for a new cylinder or one that has been meticulously maintained. During installation, always verify your ring end gap and check the small end bearing for wear. Pairing this build with a fresh top-end gasket kit and high-quality 2-stroke premix oil will ensure your mini-racer has the compression needed to pull the holeshot.

Fitment List

Year Range	Vehicle Brand	Vehicle Model
2002-2026	Yamaha	YZ85 / YZ85LW (Large Wheel)

Frequently Asked Questions

Q: Is this a Standard Size piston?
A: Yes, this is the 47.45mm piston designed for the standard 47.50mm bore. It is the correct choice for cylinders that are new or within factory-fresh service limits.

Q: Why choose Wossner for a YZ85?
A: Wossner forged pistons are stronger and hold their shape better under extreme heat than standard cast pistons. This is critical for 85cc bikes that are ridden hard at high RPMs.

Q: Does this kit include the gasket set?
A: No, the kit includes the forged piston, rings, wrist pin, and clips. A complete top-end gasket set is sold separately and is required for a professional-grade rebuild.

Recommended Pairings

• Complete Top End Gasket Set: Ensure a professional, leak-free seal and proper engine compression.
• Yamalube 2-R Premix Oil: The high-performance lubricant choice for keeping Yamaha 2-stroke engines clean and protected.

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.