It's late in the thread, I know, but I can concur with it being a crap chain. A month ago, I was having the same symptoms and waisted a lot of time before I found several causes. Unfortunately, I overlooked the obvious and went straight to disassembling and inspecting the clutch. With it spotless and me scratching my head, I just happened to notice all the damned slack in the chain. It was rubbing center stand and the swing arm. Also, over bumps and off throttle the upper half of the chain was slapping the guard.
After I tightened it up (maxing out the wheelbase adjustment bolts) I still had some binding noises. Added oil and it went away for a few days, but returned. Just replaced chain and sprockets and the bike feels and sounds much better. It's more responsive going on and off throttle as well. If I had known what to search for in the forums, I'd have saved myself so much trouble as well as the cringing embarrassment of rolling into my regular haunts with that awful sound. I learned more than I ever intended about wet clutches though.