From the article: "If the pistons hang up on a ridge at the top of the cylinders you will need to obtain a ridge cutter or reamer, available from an automotive tool store. Adjust the cutter so it will only cut a little at a time, then squirt light oil onto its blades. Now turn the cutter in each bore until the cylinder ridge is removed. Wipe up any residue or shavings with a rag.
