I built one of the first "total loss" ignition systems back in the late 60's for a Yamaha dirt tracker bike using a "reluctance head" firing a transistor that fired the coil.
The reluctance head was from a computer card punch, but basically exactly the same thing as a CPS sensor.
It sensed a high spot welded onto a crankshaft dampener.
Timing was by raising or lowering the reluctance head a bit on it's threaded mounting sleeve.
A charged battery was good for a night's racing, but I always kept a spare one handy anyway.
Had them wired with trailer connectors for a quick swap.
My brother in law at the time won the 250 cc class at the Astrodome on it that year.