Boring engines is a complex process Mark, and not remotely worthwhile unless you are a hobbyist and enjoy the job, or you are working on an irreplaceable collector's piece. Note that the Briggs in that video has an aluminium bore, making the job even less justifiable than it would otherwise be. He also glosses over a couple of difficult points, which I won't go into or this thread would be doomed to be transferred to Tech Talk. I'll just say this: I have a slightly better milling machine than he does, but I've never bored an engine in my life.
