Wossner 8330DC Piston Kit - 2002-2026 Yamaha YZ85 Standard Size C

Wossner 8330DC Standard Series Forged 2-Stroke Piston Kit - Standard Size C

Maximize the lifespan of your racing cylinder with the Wossner 8330DC Piston Kit. Designed specifically for the 2002-2026 Yamaha YZ85, the "Size C" piston is the professional solution for engines that have undergone extensive track use. At Moto-House MX, we know that 85cc cylinders naturally expand over time; this +0.02mm Size C kit is engineered to provide the exact piston-to-wall clearance required to restore lost compression and eliminate power-robbing piston rock in worn bores.

Forged from premium aerospace-grade aluminum alloy, the 8330DC offers the structural integrity needed for high-RPM 2-stroke competition. This kit features a dual-ring configuration, which provides a broader powerband and superior heat dissipation—critical for keeping mini-moto engines cool during long motos. Wossner’s permanent molybdenum disulphide skirt coating reduces internal friction, while optimized machining ensures the piston remains lightweight for lightning-fast throttle response. This 47.47mm piston is precision-matched for 47.52mm bores, allowing you to get more hours out of your YZ85 cylinder before requiring a costly replate.

Top Features: Wossner 8330DC Piston Kit

• Standard Size C (47.47mm): Precision-engineered for 47.52mm bores, providing the perfect fit for cylinders with moderate wear.
• Dual Ring Design: Enhances cylinder sealing and cooling efficiency for consistent power delivery under racing conditions.
• Aerospace-Grade Forged Construction: Denser and stronger than stock cast pistons, offering maximum resistance to fatigue and thermal stress.
• Low-Friction Skirt Coating: Permanent skirt coating protects the cylinder wall and ensures a smooth break-in and quieter operation.
• Optimized Strength-to-Weight: Machined to minimize reciprocating mass for rapid acceleration while maintaining strength in the crown and skirt.
• Complete Top-End Assembly: Includes the forged Size C piston, performance rings, wrist pin, and circlips.

Expert Pro-Tip: In the world of 85cc racing, precision is everything. As your YZ85 cylinder wears past the limits of a Size A or B piston, the Wossner Size C (47.47mm) is the go-to choice for top-level mechanics to restore mechanical tolerances. Always use a precision bore gauge to confirm your cylinder measures 47.52mm before installation. To ensure professional results, always install with a fresh top-end gasket kit and utilize high-quality 2-stroke premix oil to protect your newly rebuilt top end.

Fitment List

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

Frequently Asked Questions

Q: When is it time to move to a Size C piston?
A: You should move to a Size C (47.47mm) when your cylinder has worn beyond the specifications for Size A or B. If your bore measures approximately 47.52mm, the Size C will bring your clearances back to the ideal range for peak performance.

Q: Does this forged piston fit the Large Wheel (LW) model?
A: Yes, the 8330DC fits all Yamaha YZ85 engine platforms from 2002 to 2026, including the standard and Large Wheel versions.

Q: What are the benefits of the dual-ring design?
A: The dual-ring setup on the YZ85 provides better heat transfer to the cylinder and more consistent compression across the RPM range compared to a single-ring design, making it more durable for non-professional racers.

Recommended Pairings

• Complete Top End Gasket Set: Required to ensure a proper seal and maintain correct squish heights.
• Yamalube 2-R Premix Oil: The ultimate protection for Yamaha’s high-revving 2-stroke racing engines.

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

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