The point plate might have a play sideways when mounted but 3 bolts no tightened. This will mess up with point setting when adjusting igntion just a little. If plate move sideways, the gap will change.
From this site:
https://www.motorcycleproject.com/text/sohcign.htmlthe points backing plate is a very loose fit in the crankcase casting, which results in timing which changes with engine temperature and dwell that changes with each adjustment to the timing. To deal with that, use only a stock points backing plate. Its thick steel design resists the heat warpage that is common with the thinner steel and less rigid aluminum aftermarket plates. It also fits best, but you can
make it fit even better by lightly peening the crankcase bosses all around the plate to snug it up (see the illustration at the top of this page). It should be so tight that it will rotate only with a forceful nudge.
The site show marks from side. I hammered straight on with the sharp side of a small metal hammer. I worried about causing cracks. It worked fine on 2 engines. No more play.
timing:
http://www.hondachopper.com/garage/carb_info/timing/timing1.htmlDo not give up points. it work if knowing how to do. Point gap better with a dwell meter and adjust both points to SAME value when idling.
Advancer springs must be OK too, maybe sloppy and need to be cut 1/2 wound. Sloppy springs will cause way too early full advance.
This must be fixed even with Dyna-S and Pamco ignition. Dyna 2000 does not care.
