Oh what a shock, an NSR with badly setup powervalves!

The part you really need (apart from the butterfly itself 14321-KV3-770 or 14322-KV3-770 depending if its front or rear) is 90555-KV3-000 which is the square holed washer that stops the butterfly working its way down the shaft and wearing it's centre hole round.
That of course and the l/h threaded nut 90310-634-980.

All of them and the other two washers (90408-KV3-770 and 90437-GM0-000) are listed by Lings.com as available right now and none are very expensive.

Have a look in the parts manual, see what bits you need (and how they should be fitted), order them then be sure to read how to set it up, I've never yet seen a bike from an unknown source that had them done correctly.
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