The place to come to share your technical expertise, or just find out what the little springy thing is that's just pinged out of sight under the work-bench.
A friend recently sold his Yamaha WR450F & sold his shims to me, which just happen to be 7.5mm in diameter, the same as for the early R1s & Exup 1000s, as well as similar engined bikes. These are from the USA but are a lot cheaper than from Yamaha. Wemoto also sell them individually