A bit off topic but it has my interest. Yes, a Norton vertical twin will probably have more vibration than an XR750 vee twin. Do you have a handle (estimate) on the deflection of a standard Norton crank at say 7,000 rpm expressed as displacement and/or displaced mass. My hunch is the deflection and resulting offset of mass would amount to a fart in a windstorm when compared the vibration induced by the "static" out of balance condition of a Commando crank and reciprocating components. I vaguely recall seeing calcs done and the forces are in the thousand or thousands of pounds. I think the stock Norton crank was decent design for the intended purpose and with an improvement in the materials of construction, is suitable for significantly higher outputs. An excellent example is what Steve Maney offers; three piece bolt together but better materials - billet steel cheeks and billet steel flywheel as opposed to the factory cast steel cheeks and cast iron flywheel.