I didn't have much time before a trip tomorrow but I had to dig in a bit anyway.  I removed the flywheel, replaced the crank seal, filed the points and set them at .015.   I tried to set the timing but I could not use my dial indicator with the angled spark plug holes.  I moved the needle up one notch by moving clip down.  I will probably remove the head when I try timing again.

It started up but idle was a bit bouncy.  I could smell the premix more during the ride and the big ping noise at speed was not noticeable.  However, it did ping slightly at times.  I will remove the carb next time and check the jetting against stock settings.  

bottom line made progress but I made too many changes to definitively point to the cause.  thanks for the help, I feel more confident it can be sorted now.

When you return & have time to spare--What number pilot jet has it got & how far out is the mixture screw. Be good to hear it richen up or lean off by altering the screw just so you know its in the ball park. Did you check the points gap before cleaning, just for a reference between then & now. There's a small Oring that seals the needle jet into the bowl so it sucks from the side mounted main jet. But your problem is the opposite to 'that' Oring leaking fuel past as goes all rich.

Points were .015 after cleaning them so I just left it for the moment.  I wish I had time to check the main jet and fuss with the idle mixture to see if it could be adjusted properly.   Prior to my last round the mixture screw did not work right.  That should have alerted me to a carb problem and to clean right away.  When I get back I will take off the carb, clean and inspect.

Checking the main should take 30 seconds, just pull the 10mm bolt off the bottom of the carb and look at the jet

I always over complicate, thanks for the reality check.  I should have done that first

Glad you didn't take that as a rude suggestion, realized after the fact it could have been interpreted that way, which was certainly not the intention. Sure would be nice if too small of a main jet was the only issue!

Ha yes it sure would be nice.  I appreciate your suggestions!