Here are two traces I took a while back with my INCREDIBLY cheap DSO (Digital Storage Oscilloscope) — a toy:
I’m not sure the scale information can be trusted, nor do I have saved information about the hookup (except that I was driving an OMC "universal" magneto on a 3HP block (thanks to Don (aka Fleetwin)) with a variable speed hand drill):
Here’s primary output of the bare coil:
And another with points, condenser, and a spark plug:
