Wossner 8321D200 Piston Kit - 2022-2026 Yamaha YZ125 YZ125X +2.00mm Oversize

Wossner 8321D200 Standard Series Forged 2-Stroke Piston Kit - +2.00mm Oversize

Save a damaged cylinder or build a custom high-performance engine with the Wossner 8321D200 Piston Kit. Specifically engineered for the latest generation 2022-2026 Yamaha YZ125 and YZ125X models, this +2.00mm oversize forged kit is the professional choice for cylinders that have been bored or replated to 56.00mm. At Moto-House MX, we know that when a cylinder sustains significant scoring, moving to an oversize piston is the best way to restore "Factory Quality" compression and reliability.

Forged from aerospace-grade aluminum alloy, the 8321D200 features a performance-driven single-ring design to minimize internal friction and maximize RPM potential. Even at a larger +2.00mm diameter, Wossner’s optimized machining keeps the piston lightweight, ensuring your YZ maintains the snappy, high-revving character it is known for. The permanent skirt coating reduces internal drag and piston rock, which is critical in oversize applications to ensure a quiet engine and a smooth break-in period. This 55.95mm piston is precision-matched for 56.00mm bores, offering a durable, race-ready solution for your Yamaha refresh.

Top Features: Wossner 8321D200 Piston Kit

• +2.00mm Oversize (55.95mm): Engineered specifically for 56.00mm bores, allowing you to salvage cylinders with deep scoring or build a larger displacement engine.
• Single Ring Design: Minimizes friction and drag, allowing for the rapid throttle response and peak horsepower required for 125cc racing.
• Aerospace-Grade Forging: Significantly stronger than stock cast pistons, providing superior resistance to fatigue and cracking at high RPMs.
• Low-Friction Skirt Coating: Permanent molybdenum disulphide coating protects the cylinder wall and ensures consistent performance under extreme heat.
• Optimized Strength-to-Weight: Precisely machined to remove excess mass while reinforcing the crown and skirt for long-lasting durability.
• Complete Assembly: Kit includes the forged piston, high-performance ring, wrist pin, and circlips.

Expert Pro-Tip: Moving to a +2.00mm oversize requires the cylinder to be professionally bored and replated to a finished size of 56.00mm. This is an excellent, cost-effective way to save an expensive YZ125 cylinder. When installing the 8321D200, always verify your ring end gap and ensure your power valve has been modified or cleared for the larger piston diameter. Pairing this build with a fresh top-end gasket kit and premium 2-stroke premix oil will keep your Yamaha at the front of the pack.

Fitment List

Year Range	Vehicle Brand	Vehicle Model
2022-2026	Yamaha	YZ125 (Standard, Monster Energy, 50th/70th Anniversary)
2023-2026	Yamaha	YZ125X (Cross Country)

Frequently Asked Questions

Q: Can I drop this into a stock-sized cylinder?
A: No, this is a +2.00mm oversize piston. Your cylinder must be bored and replated to 56.00mm to accommodate this kit.

Q: Why choose an oversize Wossner piston?
A: It allows you to refurbish a cylinder that has suffered heavy damage rather than purchasing an expensive new one. Wossner’s forged technology ensures that even at a larger size, the piston remains balanced and durable.

Q: Does this kit include the gasket set?
A: No, the kit includes the forged piston, ring, 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 for your engine refresh.
• Yamalube 2-R Premix Oil: The gold standard for keeping high-performance Yamaha 2-strokes running 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.