Re: Arc Welding on engine muffler area?
You got a tap and die set? ... Why not just drill the holes the next size up and re tap them to take some M8x1.25 bolts. You'll just need to google "tap drill chart" to find out what bit you'll need to drill out the holes with, then cut the new threads with the tap and use the larger bolts or even better, studs. You may need to drill the holes in the new exhaust flange so the larger studs can go thru, but the repair would be permanent and last the life of that cylinder.
The main reason I'm even talking about up drilling and re tapping is because you got the kit, and helicoil kits can get real expensive real fast... enough to exceed the value of the cylinder so unless you got some serious porting work done or just don't want to break in a new cylinder and set of rings, it could be cheaper to just replace the jug and install a new set of rings. but since you got a tap and die set, you could just up size the threads and it'll be good to go again, just make sure you use the right drill bit size and keep it well lubed while tapping, and take your time tapping cutting one or 2 new threads then bringing it back out several times until you reach the botom to prevent the tap from loading up and getting stuck, anytime the tap feels like it's taking extra force to turn, back it out, it should go in with moderate force, but not excessive like it feels like it wants to lock up.