I just recently tore down my engine to replace a crankcase gasket due to an air leak. When I pulled the jug I had noticed that the entire piston was black! I run Amsoil Saber 1.5oz per gallon and Opti2 1.5oz per gallon, (it is easier to measure 1.5oz than 1.3oz for a 100:1 mix.) I think this is a result of not running the engine hard enough during the first few miles. I am going to put new rings on it and re-jet for a 32:1 conventional mix. Is there anything I should do to prep the old cylinder? Sorry I do not have a picture to post of the piston. It got soaked in chem-dip and looks new again already!