Old topic, I know, but I now have the same problem (stripped, or nearly so, trans drain plug). I've had too many helicoils come out with the bolt on bikes past, so don't really trust them. I like time-sets, but it's about $85 for the kit and requires removiing a bit more of the aluminum than I'm really comfortable with. The original bolt is 10mm (25/64 inch). One more millimeter puts it at 7/16", so I'm thinking of just tapping it to 7/16-20 and putting in a bolt and crush washer. Anyone tried this?