Gimme, I'm watching this one since that was the most extreme case of plug damage I've seen yet. I have to expect it's too hot a plug or detonation. If there's a lot of carbon buildup in the cylinder it can cause this. Get it running on a new plug and use Seafoam, or just use some clean ATF poured into the carb. (not one big cup at once, just pour a thin stream till it starts bogging down, let it clear up and repeat. Expect a "Little" smoke. Thank Brian (Racerone3) if that works for ya.