Namura BIG BORE PISTON KIT NA-10004 fits 1996-2004 Honda XR400R / 1999-2008 Honda SporTrax 400 TRX400EX 2X4 / 2009, 2012-2014 Honda TRX400X 2X4

MOS2 (Teflon/Molybdenum) Coated Skirts - A rolled on application process provides a bond that is 10 times stronger than other spray on coatings. Benefits include increased heat transfer, reduced friction and helping to eliminate cold seizuresMachined Smooth Heads - Reflects combustion heat and reduces carbon buildup, protecting the top of the piston. Some tests have shown this feature can increase horsepower and fuel economy by up to 6%Anodized Domes - Increases heat resistance and durability; pistons with anodized domes are 75% stronger than non-anodized pistonsHypereutectic Casting Process - Provides higher silicon content for reduced expansion rates and additional wear resistance; it also has an ability to withstand higher cylinder temperatures