tors removal

U wouldnt think the plug could get that hot from a cold start
Believe you me it certainly can, an extremely lean mixture caused by an air leak, can produce very high temperatures in a matter of seconds.

If you do not believe me, you should, as you have just witnessed it happen.
 
everything everyone else said and check to see that the top of carb where throttle cable goes in is tight they can come loose.Twist with your hand to check it,you may need to loose the screw that is suppost to keep it from stop moving. just a thought:cool: