Been having a wierd noise on my '05 fxdl.

Best I can describe it is a buzzing/flute-like vibration coming from
the back end. Can't find anything loose.
Thing is, I only hear it when the clutch lever is pulled in. Any gear, doesn't matter. Even in neutral at a stop it's there, but when I let the clutch lever out it stops, or at least becomes only barely noticeable.

No effect on performance that I've noticed.

Most searches I've done result in the opposite...noise when clutch lever is out and dissapears when pulled in (bearing problems, etc.)

Any Ideas? Get a louder pipe maybe so I can't hear it?

Thanks

 

I'd check the primary chain tensioner?