Namura NX-40001-BK Top End Kit for Yamaha YZ125, 53.95 mm Bore

The Namura NX-40001-BK Top End Kit is designed for select Yamaha YZ125 applications and provides the key components needed to restore top-end performance. This kit includes a piston, piston rings, wrist pin, retaining clips, top-end bearing, and gasket kit for a comprehensive installation. The 53.95 mm piston is engineered with an 11:1 compression ratio and is suitable for replacing worn or damaged top-end components.

Built using Namura's hypereutectic casting process, the piston features increased silicon content to help control expansion, improve wear resistance, and withstand elevated cylinder temperatures. The MOS2, or Teflon/Molybdenum, coated skirts use a rolled-on application process that creates a durable bond while helping reduce friction, improve heat transfer, and minimize the risk of cold seizures. The machined smooth head helps reflect combustion heat and reduce carbon buildup, supporting reliable piston operation.

The anodized dome adds heat resistance and durability for demanding two-stroke riding conditions. This Namura top-end kit is manufactured for dependable fit and function and is a practical choice for engine rebuilding or scheduled maintenance. It fits 2002, 2003, and 2004 Yamaha YZ125 models. Verify the model year, bore specification, and service requirements before installation to ensure compatibility.

Features:

• Complete Top End Kit: Includes piston, rings, wrist pin, retaining clips, top-end bearing, and gasket kit
• 53.95 mm Bore: Designed for compatible Yamaha YZ125 top-end applications
• 11:1 Compression Ratio: Supports the specified engine configuration
• MOS2-Coated Skirts: Helps reduce friction, improve heat transfer, and minimize cold-seizure risk
• Machined Smooth Head: Helps reflect combustion heat and reduce carbon buildup
• Anodized Dome: Increases heat resistance and piston durability
• Hypereutectic Construction: Provides controlled expansion, wear resistance, and improved high-temperature performance
• Fitment: Fits 2002, 2003, and 2004 Yamaha YZ125 models
• Brand: Namura
• Manufacturer Part Number: NX-40001-BK
• Vendor Part Number: 185-4001B