2000 Yamaha YFM400FWA(M) Factory Service workshop Manual, Page 141Get this manual

CAMSHAFT, ROCKER ARMS AND VALVES

Inspect the surface of the rocker arm shafts
Blue discolorationpittingscratches Replacecheck lubricationMeasure the inside diameter of the rocker arm holesOut of specification ReplaceRocker arm inside diameter: 12.00012.018 mm (0.47240.4731 in)
Measure

the outside diameter of the rocker arm shaftsOut of specification ReplaceRocker arm outside diameter: 11.98111.991 mm (0.47170.4721 in)

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