2004 Official factory service manual for Yamaha YFZ450S ATV Quad., Page 161Get this manual
VALVES AND VALVE SPRINGS EBS00238
REMOVING THE VALVES AND VALVE SPRINGS The following procedure applies to all of the valves and related componentsNOTE: Before removing the internal parts of the cylinder head (e.g valves, valve springs, valve seats), make sure the valves properly seal1Remove: valve lifter valve pad NOTE: Make note of the position of each valve lifter and valve pad so that they can be reinstalled in their original place