I hate to have to add to this but my brothers bike (07 yz 450) has recently started making the same ticking noises. Its not the cluthc, I know the clutch quites down when you pull it in. Its a ticking like the lobes on the cam are loose or like the cam chain is rubbing or something similiar. The ticking noise has a slow rythmn when idleing and a faster ticking as you give it gas. ...... THIS IS NORMAL??? I made him stop riding yesterday at the track in order to avoid doing something serious to the motor. Yes his has a skid plate. I dont know what you all think.