Hi, does anyone no where to find information about the Norton dunstall engine 810. What are the differences between the 750 and 850 commandos. Does the dunstall have a different crank. Are the rotor on 750 and 850 interchangeable does the 810 have a different rotor and timing mark as compared to the 750 and 850.I have been told I have a dunstall engine however I have yet to prove this.I have an 850 and 750 commando a british parts supplier told me the 850 and 750 rotor are same yet the 850 rotor I have will not fit the 750. So of course I am wondering if the 750 crank having the larger crank shaft and this is preventing the 850 rotor to fit is the 810 dunstall crank anyone?