I have the same noise that just started up on my 08 road king on my last long ride. It was getting so loud if I pull in the clutch that the boss riding on the seat behind me asked if something was wrong. (I was pulling in the clutch at speed to quiet the motor down to better hear the noise.)

To me it sounded like a nut or small bolt getting flung around inside of the timing cover. Not a very pretty sound.

I finally pulled over and listened at idle but didn't hear anything, then shut down to check the oil levels "OUCH!" and found nothing wrong. When I started back up and drove off it was quiet and stopped doing it. I think if/when I hear it again i'm gonna dig a little deeper. If I find something I'll be sure to update everyone.

Mike

 

I have exactly the same noise only when in 5th. If you find a solution let me know.

 

If it's not external it might be a hydraulic lifter getting weak, a weak lifter will allow a bit of play in the valve train that can cause a noise like that.