Strange sound on my xp

[team-x]

What maxwell said. I'm willing to bet the bottom of your pipe shield broke off near the y-pipe and is ratteling around in there. Mine did the same thing

 

[SUMMIT TREE]

The handle of my muff pot came off one time and worked its way to the ring gear……boy does that make some neat noises….

 

[kimrick]

Also check your brake disc for play. My daughters does this and we found the brake pads worn down and the disc rattled when idling and off the throttle.
Let us know what you find.
All good posts above for mystery noises.