That giant Preston Petty fender can't be helping cooling too much. The 390 had one of those when we got it, and I don't know if someone did this or if the fender came that way, but it had a bunch of half-inch holes in the back of it so air would flow to the cylinder. Don't know how much of a difference that would make, but I always thought that was interesting when I was four years old and looking straight up at the massive tower of bike before me.