2002 Yamaha YFM660 Grizzly factory service and repair manual, Page 170Get this manual

VALVES AND VALVE SPRINGS

3.Check: Valve face Pittingwear Grind the faceValve stem end Mushroom shape or diameter larger than the body of the stem Replace

• ATV
• Jet Ski
• Outboard Motors
• Personal Watercraft
• Snowmobiles
• Stern Drives