I lost a chunk of crankcase recently losing a mounting lug in the case by starter clutch.

I hand drilled holes each end of the hole to bridge the gap with wire. I used a strong coat hanger, flattened it in the centre, and a helicoil held in place with a dab of superglue. To get everything lined up I put the cover on loosely and used wax on the mounting bolt threads to stop it sticking to the helicoil. When it was all set up I used the JB Weld and sanded it down afterwards. The repair was strong enough that I could grip the repaired section and wobble it making the hole bike move on it's stand.

Been using it for a week now and it all seems good.

Neat job.

Hmmm I could do with using that to stick the bits of damaged case back to together