The only thing a ridge reamer does, is make the piston easier to remove, so the piston ring will not hit a square ridge when bumping the pistons out. If it has a ridge you can catch with your finger nail, it needs to be bored. If you use the ridge reamer wrong and cut too much, you may ruin the bore so it cannot be bored. If the cylinders are worn tapered, the piston ring will expand and contract as it goes up and down the bore. When you bend a piece of wire back and forth, it breaks, same thing with your piston rings. I have seen a lot of engines, guys honed and just put back together, you can pull the pistons and shake the rings off after a few thousand miles.