Joe, the fat engine will run hot. Carbon build up, will run hotter. The seat of pants jetting is fine. You defined the main jet, what about the others? Somewhere you are pretty rich, maybe them stinking valves! No one has made mention if these filters effect carb flow? Are they serviceable, or throw away? It seems to me that we got sold on some sort of check valves that went on the end of the carb hoses before.