1999-2004 Honda TRX400EX FourTrax Service Manual, Page 95Get this manual
CYLINDER HEADNALVE Remove the following:spring retainerinner and outer valve springs -valvestem sealvalve spring seat
Mark all parts during disassembly so they can be Dlaced back in their original locations
Remove the carbon deposits from the combustion chamber and clean off the gasket surface, being careful not to damage the gasket and valve seat surfaces