mine has been doing that since it was new when riding hard in hot weather.
Yeah, Amsoil 20/50.
On the plus side, after talking to the guys at HD, I've checked all the logical things, and they all check out good. So I guess I'm about to button her back up with a qt of HD formula+ primary lube, and see what happens.
Never made this noise before riding hard in the hot (all we have here in Texas is hot), and the only changes were the chain not being floppy loose and the oil. Hope it's just the oil, and I'll leave the chain a little closer to the loose side of things this time.