RivetHog. Having the Sprocket shaft shoulder NOT contacting the flywheel face makes sense since this ensures a full seating of the shaft. What few I've reassembled I just torqued the nut to 120 lbs., red loctite and the nut keeper. I'm not going to use this particular flywheel assembly in this build but I will do an inspection on this particular area. If you look carefully at the picture the outer shoulder is cracked inward, not outward which I think would be the case with shoulder interference/ shaft seating. Metal fatigue ?
I get your drift I know the motor needs to come apart, I guess i'm hesitant because I don't have all those fancy reamers, or a press and I don't want to start buying tools that I may use once in a lifetime. I might just yank it apart today and stop messing around. I think it's going up to 32 deg today. Won't be bad if I work in the sun.