Motorcycle Repair: XJ900 front brake vibrates only when braking, brake rotor, brake calipers

Question
When I use the front brake on my 1990 XJ900F there is a continuous shudder. This is quite pronounced and the brakes do work well. Nothing happens till I brake and it stops when I let go. Bike seems to have been well maintained by the previous owner and generally handles well. Where should I start?  

Answer
Colin, generally the only thing that creates brake shudder is a warped brake rotor. Unless your brake calipers are loose on the mounts or something else is worn/damaged, my bet is that the brake rotor has gotten warped. Some machine shops with blanchard grinders can refinish them, otherwise you may have to find a replacement.

Bill Silver