Piston is toast, cylinder will clean up.
First I use some 200 grit wet/dry and diluted dish detergent when sanding. It gets the oil and any carbon off, so acid can do it's thing on the aluminum. Then a long q-tip with acid to take off underlying transfer. Rinse with water then repeat as required. Finish up with 400 grit.
First I use some 200 grit wet/dry and diluted dish detergent when sanding. It gets the oil and any carbon off, so acid can do it's thing on the aluminum. Then a long q-tip with acid to take off underlying transfer. Rinse with water then repeat as required. Finish up with 400 grit.