Howdy, JJ. All the easy temp stuff might get ya by and I'm guessing you don't want to hear it, but really should be done right. The engine will slowly turn left and then yer walking her home. Great advice above and I would do it in order of ease. First try to notch the broken studs and try and get a screw driver to back em out. If that fails, and it will work on the first 2 and fail on the third. Just Murphy's law, there, I would get/borrow an extractor kit. If ya get a really cheap one, it'll just frustrate ya. If all else fails, I would drill em out and tap new, larger threads. Almost any new studs will be better but my personal choice is automotive. They are made for this application and are gritty and hang in there better, don't shear or shatter like the kit ones. Just the right tool/part for the job. Ya might be tempted to go with stainless or some high grade material. But is a waste and this will work better.
This is just the good advice you already received above but in order of ease. Just my HO an' 2 cents.
Ride safe!
Edit; Dang, I forgot heliocol!
https://www.google.com/search?q=hel...d=chrome&ie=UTF-8#q=helicoil+for+engine+studs
This is an oldy but a goody thread from way back on your problem;
https://motorbicycling.com/threads/drilling-and-tapping-jb-weld.57153/
Just sayin' it's been tried a lot. And folks don't want ya to get hurt. And it can be dangerous at worst and a waste of $ & time at best.
