Taper provides about 95% of the holding power.  Make sure both crank and flywheel tapers are clean and dry.  If there is minor damage, some fine lapping compound can help seat the flywheel taper to the crank taper.  But make sure you get ALL the lapping compound removed.

I will install a new crank key tomorrow and will meticulously clean and prep the tapered bore and shaft before reassembling. I typically tighten my flywheel nuts with a half inch drive pneumatic impact! I don’t have anything equivalent to the tool in your photo Morley.

The max gap on the points seems good being snug on a .015 feeler gauge. So I will take this one step at a time. It would not start today and it did kickback again while trying to start it. That’s why I pulled the flywheel.

And kickbacks will definitely bust a flywheel key if the taper and nut torque are not right!

By memory it was misfiring & faltering which will be interesting to see if that is sorted but an overly wide plug gap could go towards that. Look forward to the result.

Correct. It was misfiring & faltering, but it evolved into a no start condition with frequent kickbacks. I had already reduced the gap to 20 on my brand new 4054 spark plug with no change.

My local Yamaha shop did not have the crank key in stock, or the two sealing washers for my petcock screws which are leaking now that I installed a new Yamaha petcock. So unfortunately this will be on hold until next week. Stay Tuned!

Any relation to Eric Idle?! 

Hmmmm 

youtube.com/shorts/Po_I7u_D8gs?feature=shared

I’ll bet with a BFH you could hit it hard enuff to tighten that wire!
(:p

Not had your magnets out of the flywheel & inserted one back to front cleaning things. If they're the screwed in type. Stranger things have happened--at where I worked lol. Also if soldering a condenser us a pain, just mount an external one at the coil & tuck the wire into the wire ontobthe coil, if you can find a condenser with a mounting bracket. Or buy a Honda coil shhh did I say honda, as their coils come with condensers mounted. OK I'm just randomly waffling. Might have a stator coil issue. Are any of your base plate coils coming loose in the windings.

I think you found the problem Bill.  Great job!