On top of all the regular rattles, my XTR developed a new higher pitched rattle that sounded like a tin can of pins being shaken around (as opposed to a bucket of nails if that helps the description). Would only happen on the move and worse at certain revs. Drove me nuts as it seemed to drown out all the noises.

After weeks of riding around pressing and pulling at bits of the bike while maintaining the correct rev range, looking like a goose and trying not to fall off... I discovered it! It was the fuel filler cap. So... with no idea how the complicated fuel cap looked on the inside, I dissembled it. Screws and springs, various plates, a little plastic X thing, a little ball bearing, and lock sliders all burst out as if under pressure and bounced to different regions of my shed floor... You know that moment: "Oh crap, what have I done?"

Anyway, by some quirk of karma, I was able to locate all the strewn parts and clean em up, lube and reassemble in the manner I hoped was correct. And problem solved... not entirely sure what was the issue was, maybe the spring that held the little lock flap had come adrift a bit - but everything is much tighter now with fitting and turning the key, etc.

So... just sharing in case you have a similar rattle, or are curious about opening up the fuel cap