Namura NX-40026K Top End Kit for 1992–1994 Yamaha YZ250, 67.94 mm Standard Bore, 11:1 Compression

Refresh the top end of your two-stroke motorcycle with the Namura NX-40026K Top End Kit. Designed for the standard-bore 1992, 1993, and 1994 Yamaha YZ250, this ceramic competition kit includes the piston, piston rings, wrist pin, retaining clips, top-end bearing, and gasket kit needed for a comprehensive top-end rebuild. The 67.94 mm piston is engineered for an 11:1 compression ratio and dependable performance in demanding riding conditions.

The piston uses a hypereutectic casting process with increased silicon content to help control expansion, improve wear resistance, and withstand higher cylinder temperatures. MOS2, or Teflon and molybdenum, coated skirts are applied using a rolled-on process that creates a strong 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 consistent operation and piston protection.

An anodized dome adds heat resistance and durability, while the included rings, wrist pin, clips, bearing, and gasket kit provide the essential components for installation. This Namura top-end kit is manufactured for direct fitment on 1992–1994 Yamaha YZ250 models. Verify the model year, cylinder condition, and required bore specification before installation to ensure proper fit and clearance.

Features:

• Complete top-end kit includes piston, rings, wrist pin, retaining clips, top-end bearing, and gasket kit
• 67.94 mm standard-bore piston designed for an 11:1 compression ratio
• MOS2 Teflon and molybdenum coated skirt helps reduce friction, improve heat transfer, and minimize cold-seizure risk
• Machined smooth piston head helps reflect combustion heat and reduce carbon buildup
• Anodized piston dome improves heat resistance and durability
• Hypereutectic casting process provides controlled expansion, increased wear resistance, and improved high-temperature performance
• Fits 1992 Yamaha YZ250, 1993 Yamaha YZ250, and 1994 Yamaha YZ250
• Brand: Namura
• Manufacturer part number: NX-40026K
• Vendor part number: 185-4026