Well I have ran nitro for a long time and I know how to tune and everything. My question is what is the top of the piston suppose to look like?? Mine is like a Goldish color and I know that color on a glow plug it good but what about on a piston??? ( I know what a piston that has run to lean looks like. ) and my last question is what would a piston look like if it has ran too rich?? I use to remember but I can't lol!!