Cylinder Hone

Once again , many riders choose a rebore for new oversize pistons , with a final honing ,when in fact a Norton needs head work with new seals first. At least in my experience (s). I've never seen a Norton wear out the pistons / bores. A competent machine shop should be trusted to do this work . Again , valves , guides , modern seals should suffice first.

More likely than wear these days is that the rings have rusted to the walls because the engine has been sitting for a long time or cylinder wall damage of some sort due to a previous bad rebuild. I've had to do a number of rebores to correct damage even though the bores were probably within spec.