Great thread, I wish I found it earlier. I have the exact same rattle. I took off all my plastics, windscreen, horn, and headlight housings. From there I rode up in down a country road in 2nd with my throttlemeister locked at 5800 rpm's. Finally after a few minutes, I was able to find that the rattle was coming from that black key lock box. To verify your bike's rattle problem too, just squeeze the black box (finger on the top and bottom) behind the key and the noise stops.
Thanks for your help Luker669, now I just need to apply your fix!
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