The Namura NX-40000K1 Top End Kit is designed for the 2001 Yamaha YZ125 and provides the essential components needed to refresh the engine’s top end. This kit includes a piston, piston rings, wrist pin, wrist-pin clips, top-end bearing, and gasket kit for a convenient, application-specific rebuild. With a 53.94 mm standard-bore piston and 11:1 compression ratio, it is engineered to match the original cylinder configuration for reliable fitment and performance.
The piston features Namura’s MOS2, or Teflon and molybdenum, coated skirts. The rolled-on coating process creates a durable bond while helping reduce friction, improve heat transfer, and minimize the possibility of cold seizures. Machined smooth heads help reflect combustion heat and reduce carbon buildup, supporting piston protection during operation. Anodized domes improve heat resistance and durability, while the hypereutectic casting process increases silicon content for controlled expansion, added wear resistance, and improved resistance to elevated cylinder temperatures.
This Namura top-end replacement kit is intended for riders and technicians servicing a 2001 Yamaha YZ125. Confirm the motorcycle year, model, cylinder condition, and required bore specification before installation. Proper assembly, ring orientation, clearances, lubrication, and break-in procedures are essential for dependable service. Manufacturer part number NX-40000K1 and vendor part number 185-40001 identify this kit for ordering and application reference.
Features:
- Application: Fits the 2001 Yamaha YZ125
- Kit contents: Includes piston, rings, wrist pin, clips, top-end bearing, and gasket kit
- Bore size: 53.94 mm standard bore
- Compression ratio: 11:1
- Skirt coating: MOS2 Teflon and molybdenum coating helps reduce friction, improve heat transfer, and minimize cold-seizure risk
- Piston head: Machined smooth head helps reflect combustion heat and reduce carbon buildup
- Piston dome: Anodized dome improves heat resistance and durability
- Construction: Hypereutectic casting provides controlled expansion and enhanced wear resistance
- Brand: Namura
- Manufacturer part number: NX-40000K1
- Vendor part number: 185-40001
Fitment:
2001 Yamaha YZ125