Restore top-end performance with the NAMURA NA-10003-6K Top End Kit. This high-compression kit is designed for Honda TRX400X and TRX400EX Sportrax models and includes the essential components needed for a complete top-end rebuild: piston, rings, wrist pin, retaining clips, top-end bearing, and gasket kit. The piston features an 86.47 mm bore size and an 11:1 compression ratio, providing a performance-focused replacement for compatible engines.
Feature: The MOS2, or Teflon/Molybdenum, coated piston skirts use a rolled-on application process that creates a bond claimed to be 10 times stronger than many spray-on coatings. This coating helps improve heat transfer, reduce friction, and minimize the risk of cold seizures during operation. The machined smooth head reflects combustion heat and helps reduce carbon buildup, supporting piston protection and consistent engine performance.
Feature: Anodized piston domes improve heat resistance and durability, while the hypereutectic casting process increases silicon content to reduce expansion and improve wear resistance. This construction is designed to withstand higher cylinder temperatures and maintain reliable operation under demanding riding conditions. The included gasket kit, rings, wrist pin, clips, and bearing provide the supporting components needed for installation.
The NAMURA manufacturer part number and vendor part number for this kit are both NA-10003-6K. It fits 2012–2014 Honda TRX400X models and 1999–2005 Honda TRX400EX Sportrax models. Verify the vehicle model, year, bore specification, and engine requirements before installation to ensure proper fitment.
Features:
- Complete top-end kit includes piston, rings, wrist pin, retaining clips, top-end bearing, and gasket kit
- 86.47 mm bore size with an 11:1 high-compression ratio
- MOS2 Teflon/Molybdenum-coated piston 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 dome improves heat resistance and piston durability
- Hypereutectic casting process provides reduced expansion and increased wear resistance
- Fits 2012–2014 Honda TRX400X and 1999–2005 Honda TRX400EX Sportrax models
- Brand: NAMURA; manufacturer and vendor part number: NA-10003-6K
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