is your pipe turning blue, or baking off its paint? if you are too retarded, you will be dumping more late burning gas, and the pipe will shove it back in, heating the pipe, jug, and skirt of the piston. Totally counter intuitive. Advanced runs cooler... sometimes. Besideds its cheap to change. go through a wider range... etc. The compression thing makes me think either early or late burn/ detonation/ that sort of thing. IS the piston getting black down the skirt on the port side?