In the motorcycle shop I worked at in Freeport , Orient Express ,we set our Sunnen bore gauge with micrometers held in a micrometer holding vise . . We set the micrometer to piston size and bored and honed to size straight and round within .0002" which is pretty straight for sleeves almost 3.5" in diameter and 6" long . That is a very nice piece , wish we would have had one of those.