Just hoping this might help someone as I myself just sifted through the site for this problem and didnt find too much.
Riding home from a typical commuter day probably about two hours of ride time total with about 15000 on the clock I started noticing a rattle when shifting from N to 1st and giving some throttle to get going again at stop lights. It felt like the clutch shifter was violently jerking back and forth. My heart fell into my butt since I had been practicing clutchless shifting, visions of loose gears erupting from the side of my engine danced in my head.
When I got home I put the bike up on a swingarm stand and noticed the chain was unexpectedly very loose so I tightened it up and the lock nut on by the clutch lever was freely spinning so I adjusted the clutch cable as well.
Took it for a spin down the street and voila no more crazy noises, this is my commuter and I have a 4 hr round trip planned for tomorrow so moral of the story is a very loose chain can make the 919 do crazy things. If things go bad tomorrow I will recant.