i say it's too lean somewhere, and my need to be shimmed. The plug is distorted from the compression, and the white carbon residue is from being too lean most likley on the low speed. It has dark coloring likes if it's been idleling for a long period of time then when you go out to run hard it cooks on to the plug and all that deposit is also on the head button which is not doing any good for your next plug. So I would pull the head button and clean off the fuel burn.