Wierd sound from exhaust.Under everything but idle the bike now makes like a sewing machine sound almost like a pressure leak in the exhaust.Not a poping or backfire but more high pitch whistle after each exaust cycle?Any ideas ?

sounds like maybe the baffle has come apart a little bit and is restricting the exhaust flow especially near the end of the pipe.....when you open the throttle, exhaust volume increases dramaticly and a restriction will cause a little leak up stream to produce this noise.....block the tailpipe while it's running, you will hear the same noise

Ww