Engine died during break-in

I rarely try to see spark at the plug electrodes,of used plugs; it can just become too frustrating.The gaps are too small to see properly, and the spark all too-easily leaks away up the soot to the shell.
Instead, I install a couple of spark testers in the ends of the wires. Mine have an adjustable air-gap, that I crank open to at least 1/4".
My Accell square-top yellow SuperCoil easily fires .5 and more.