2004-2005 660 Yamaha Rhino Factory Service Manual, Page 159Get this manual
VALVES AND VALVE SPRINGS
cInstall the valve into the cylinder headdTurn the valve until the valve face and valve seat are evenly polished, then clean off all of the compoundNOTE: For best lapping results, lightly tap the valve seat while rotating the valve back and forth between your handseApply fine lapping compound to the valve face and repeat the above stepsNOTE: After every lapping operation be sure to clean off all of the compound from the valve face and valve seatfApply Mechanic's blueing dye (Dykem) to the valve facegInstall the valve into the cylinder headhPress the valve through the valve guide and onto the valve seat to make clear patterniMeasure the valve seat width againIf the valve seat width is out of specification, reface and relap the valve seatLLLLLLLLLLLLLLLLLLLLLLLLLLLLLLLL