This got a bit out of hand but heres a tip for you if you just fucked the screws out from your oilblug and the bike happens to be a dyna or anykind of harley and you you cant find a big enough of a bolt and you only have a 14mm v-coil with a 1,25 screw (thats the one they put in lot of the sparkblugs).
So first put the sparkblug in the lathe and turn the screw bit of the blug out
Then find a bolt you wanna use as a base and turn it so that it fits inside sparkblugs screw.
After that you just weld them together and cut it if its too long.
-flink