Silversurfers correct about the muriatic acid. It works, I tried it about a year ago
When the engine gets hot the piston expands more than the cylinder does. With all that heat and friction the aluminum from the piston is deposited.
ORIGINAL: Silversurfer
I met a 115 this past weekend where it has already been toasted. Owner stated that (paraphrased) it got so hot the coating on the cylinders was burned off. Baffles and mixture again.
Hopefully he will be at copper Sunday, I gotta see that.