It's overheating while driving at highway speed. I drove it about 15 miles last night to add a little racing fuel. It wouldn't turn over when I tried to restart; after it cooled about 5 minutes it turned over slowly and started. It sounds like the timing it too high; I'll try to back it off a bit and see what that does. Regarding the richness of the carb. The shop manual says to back off needles 5 turns from seated to begin setting procedure. I've got mine at about 4 full turns out. Does that sound right?