Stripped threads in crankcase

The threads in the crankcase that allow attachment of the ignition cover on my 76 250 WR are stripped. The hole in question is the bottom left. They were already damaged when I bought the bike and the previous owner just gobbed on sealant to keep water and dirt out. Has any one made a repair like this before? Is it ok to tap a size up? Is there a concern with overcutting and causing a leak into the crankcase or is there enough material there to allow this type of repair (OR is there even a way a path could be created internal to the case)? I can't tell how far in the threaded portion is.

Maybe you have tried something else with success...any thoughts???

Thanks,
Mark

drill it and tap it out for the stock sized bolt, they make really small helicoil sets just for this kinkd of thing. go to a napa or fastenal and they will either have it or be able to order the stuff you need. will be around $30 but youll have the stuff next time you need to fix some bad threads.

also buy the propper sized drill bit when your at the store.

Great advice guys! My next concern was finding a larger bolt with a head that would match the other three. This way I can use an original.

Thank you.

I dont know how bad the threads are stripped but you can try wrapping the bolt with some teflon tape, it should give you enough torque on the bolt.

Its not really a sealed surface so you dont need to crank the bolts down to hard

Im not positive but I think the case is magnesium and cutting threads into that can go bad real quick.

There is some thread engagement but not enough to get the torque I need to make the cover seal. You make a good point about not needing too much torque to seal so I will try some teflon tape and see what happens. If not I will explore either the helicoil or timeserts option.

Either way T I will post an update with pictures and process instructions that I follow. I just finished taking the engine out and fenders off this morning!