Originally Posted by crassius
the plug leak could cause several things that will rob you of power - it needs fixing, so do so & see
head comes off easily for sleeving or helicoiling if you don't have easy access to another head
fixing this might even reduce the spit-back from the carb
You could bring it to a machine shop to install the Helicoil if it seems to be economical and you don't want to buy the special sized drill bit and Helicoil insertion tool and coil insert. I can say once those are installed I have never had a problem ever with cross threading again.
There are other non-spring type inserts, but my thought on those is there not worth using as they are as soft as the white metal they cast the head with.