Originally Posted by mapbike
At my local Autozone auto parts store they sell kits with everything needed to tap the hole and install a helicoil/thread inset for the original M6x1.00 thread stud, you can also thread it up to 1/4-20 size if the hole isnt to wall-erd out.
Yes they ain't cheap and you can probably buy a new engine case for what the kit cost, but it is a simple and easy fix that will get you back on the road quickly and that set of threads will be bullet proof from there on out, use loctite on all the mounting fasteners, had the same issues when I built my first bike, loctite was the cure for all of my engines fastener issues.
New case for $15 plus shipping
Is it hard to install a new case ? That might be a wise investment