The Namura NA-10003-2K Top End Kit is designed for select Honda TRX400X and TRX400EX Sportrax applications. This high-compression kit includes a piston, piston rings, wrist pin, retaining clips, top end bearing, and gasket kit for a comprehensive upper-engine rebuild. The 11:1 compression piston is manufactured using a hypereutectic casting process that increases silicon content for reduced expansion, improved wear resistance, and reliable operation at elevated cylinder temperatures.
The piston features MOS2, or Teflon/Molybdenum, coated skirts applied through a rolled-on process for a durable bond. This coating helps improve heat transfer, reduce friction, and minimize the risk of cold seizures. Machined smooth heads reflect combustion heat and help reduce carbon buildup, supporting piston protection and consistent engine performance. Anodized domes further improve heat resistance and durability compared with non-anodized piston designs.
Fitment: This Namura top end kit fits 2012-2014 Honda TRX400X models and 1999-2005 Honda TRX400EX Sportrax models. Verify the vehicle year, model, bore specification, and engine requirements before installation. The manufacturer is Namura, and the vendor part number is NA-10003-2K.
Features:
- Complete top end kit includes piston, rings, wrist pin, retaining clips, top end bearing, and gasket kit
- 85.47 mm +0.50 mm piston size with an 11:1 compression ratio
- MOS2 Teflon/Molybdenum coated skirts help 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 reduced expansion, increased wear resistance, and improved high-temperature performance
- Fits 2012-2014 Honda TRX400X and 1999-2005 Honda TRX400EX Sportrax models
- Brand: Namura; manufacturer and vendor part number: NA-10003-2K
Fitment:
1996 Honda XR400R
1997 Honda XR400R
1998 Honda XR400R
1999 Honda TRX400EX Sportrax
1999 Honda XR400R
2000 Honda TRX400EX Sportrax
2000 Honda XR400R
2001 Honda TRX400EX Sportrax
2001 Honda XR400R
2002 Honda TRX400EX Sportrax
2002 Honda XR400R
2003 Honda TRX400EX Sportrax
2003 Honda XR400R
2004 Honda TRX400EX Sportrax
2004 Honda XR400R
2005 Honda TRX400EX Sportrax
2006 Honda TRX400EX Sportrax
2007 Honda TRX400EX Sportrax
2008 Honda TRX400EX Sportrax
2009 Honda TRX400EX Sportrax
2012 Honda TRX400X
2013 Honda TRX400X
2014 Honda TRX400X