That is exactly what reversion sounds like. Depending on the cam it can be negligible to very noticeable. I noticed it way more with the heavy breather vs the oval style Harley intake.

 

Most likely the butterfly valve in the throttle body. It becomes more pronounced when using a open style air cleaner. Even louder with a performance cam. On the CV carbed bikes, the slide would rattle pretty good under the same circumstances.

 

 

I've adjusted the pushrods numerous times something is not right the only things I haven't changed is the pushrods and rocker arms

 

Most likely the Cam and open AC, Mine sounds the same but goes away at 2600ish rpm's.

 

That makes me feel a lot better

 

I just did a Stealth AC and W222 cams and at certain RPM's I here something very similar. In fact, I feel I don't even notice it anymore.