2004 Official factory service manual for Yamaha YFZ450S ATV Quad., Page 300Get this manual
SWINGARM AND DRIVE CHAIN
4Check: O-rings Damage Replace the drive chain drive chain rollers Damagewear Replace the drive chain drive chain side plates Cracksdamagewear Replace the drive chain5Lubricate: drive chain Recommended lubricant Engine oil or chain lubricant suitable for O-ring chains 6Check: drive sprocket driven sprocket More than 14 tooth wear Replace the drive chain sprockets as setBent teeth Replace the drive chain sprockets as setb Correct Drive chain roller Drive chain sprocket