I have a small (7 hp, 1 cylinder) 4-cycle engine (Kohler) that won't start. It has a magneto ignition. A plug resting on the head sparks; but, for a number of reasons, I still suspect the ignition is 'weak', and doesn't fire strongly enough under compression to produce combustion. But, I'm not at all certain of this, and I don't want to spring for a new coil just to try it.
What I'm thinking to do is take an old automotive ignition coil and a battery, and just run it off the points on this engine. If I can find it, the coil would be from a Chevy (straight) 6.
My question is whether I need to put a resistance in the coil's primary circuit. I ask because I have vague memories of a resistor like that in the cars (bypassed when the key was in the crank position). Plus, running a single-cylinder (instead of 6), the points would be closed more of the time, and so the average coil current would be higher.
TIA, George