I'm in the process of removing the AIS from my bike. I intended changing the drain bolt and washer the same as yourself although the bolt is ok.My local Yamaha dealer had the copper crush washer,the same as you've taken off, but said the bolt was on back order, so I'll reuse the original bolt. Personally I'd cut down the new bolt you've got to the original length and get the proper copper crush washer, or a correct sized one from a motor factors would be good enough.
