I don't know the milage on your X..... but this would be an opertune time to check those pads.... as you're going to have to pull that caliper off...
On the caliper is 2 torq bolts that attach to a chrome bracket that has a hole in it for the front axle....
on the top side of that caliper is a steel strap (1 bolt) that goes back to the rear fork (same side)and mounts with 2 bolts there. It sounds to me that you lost one of the top bolts for that strap. DON'T ride it until you get this fixed. Its dangerous, and its gonna screw something up bad.
If all the bolts are there, I'd then guess on of them is loose....
You'll be able to see what I'm talking about, if you get down on your back with a good lite.
If not,.... go to
http://www.excelsiorhenderson.com/pages/tech/pdf/EH_Factory_Parts_Catalog_X.pdf and you can look it up in the parts book. This is also on this web site under downloads in the "Tech" section...
