A Toro with a small 4cyc suddenly will not start. It 'kicks back" when
you try and start it. A friend suggested that perhaps the flywheel had
sheared it's pin and the timimg is bad.

I took the cowling off and I'm not sure if it's sheared or not. I
appears
I'd have to hammer it off to take a closer look.

The fly wheel mounted magnet passes over the pickup twice for every
one cycle. Is there something that shorts out the
energy durning the non firing exhaust cycle?

Could the ignition be 180 out? On one pass, as the
magnet passes over the coil, the value is wide open.
On the other it is closed.