The Namura NX-40001K Top End Kit is designed to restore top-end performance and dependable operation on compatible Yamaha YZ125 models. This standard-bore kit includes a piston, piston rings, wrist pin, retaining clips, top-end bearing, and gasket kit, providing the primary components needed for a complete top-end rebuild. The piston is engineered for the 53.94 mm standard bore and 11:1 compression configuration.
Namura uses a hypereutectic casting process that increases silicon content to help control expansion, improve wear resistance, and withstand higher cylinder temperatures. The piston skirts feature a rolled-on MOS2 coating made from Teflon and molybdenum. This bonded coating helps reduce friction, improve heat transfer, and reduce the risk of cold seizures. Machined smooth heads help reflect combustion heat and limit carbon buildup, while anodized domes improve heat resistance and piston durability.
Fitment: This Namura top-end kit fits 2002, 2003, and 2004 Yamaha YZ125 motorcycles. Confirm the motorcycle year, engine configuration, bore specification, and compression ratio before installation. The manufacturer part number is NX-40001K, and the vendor part number is 185-4001A.
Features:
- Complete top-end kit includes piston, rings, wrist pin, retaining clips, top-end bearing, and gasket kit
- 53.94 mm standard-bore piston designed for an 11:1 compression configuration
- MOS2 Teflon and molybdenum coated skirts help reduce friction, improve heat transfer, and reduce the risk of cold seizures
- Machined smooth piston head helps reflect combustion heat and reduce carbon buildup
- Anodized dome improves heat resistance and durability
- Hypereutectic casting process provides controlled expansion, increased wear resistance, and improved high-temperature capability
- Fits 2002, 2003, and 2004 Yamaha YZ125 models
- Brand: Namura; Manufacturer part number: NX-40001K; Vendor part number: 185-4001A
Fitment:
2002 Yamaha YZ125
2003 Yamaha YZ125
2004 Yamaha YZ125