The engine did not have a magneto but a model T coil for the spark, and that could be run either with a six volt car battery or with a four-pack of telephone batteries. I think I have seen both used just like on the old Model T which used either, until the self starter.
But the hit and miss name came from the speed control, the governor. Can't remember where it was on the engine but it was a little shaft with variable position weights on it that would lift by centrifugal force depending on the speed, and as they lifted they moved a lever which was connected to the front of the engine where the exhaust and intake valves were along with the spark plug. It may have been integral with the rod and lever which pushed the exhaust valve open for the exhaust stroke. So when the gyro sensed that the rpm was up to or past the running speed the lever would keep the exhaust valve open all the time instead of regulating the valve according to the power stroke and the exhaust stroke. That meant that there was no compression and no suction to draw fuel into the cylinder so there was no explosion, only the "miss". As the flywheel momentum died either by inertia or load and the gyro mechanism slowed the lever allowed the exhaust valve too close for the power stroke and there was a "hit" until the proper running speed was regained.
Along with this exhaust valve arrangement the intake valve worked automatically with no mechanical help. The spring on that valve was fairly light and the slightest negative pressure on the intake stroke would pull it open leaving enough vacuum to draw the fuel up from the tank below. Probably not a very fuel efficient system, but it worked. Also for starting one could reach both the intake valve spring — careful not to get your finger on the near-by spark plug — and the flywheel. It was then free-wheeling until the flywheel had enough energy to carry it through the compression stroke, so let go the intake valve and it would chug along as it should, hitting and missing depending on the load.
Here is a picture of what ours looked like or maybe a later model, but we had no shield over the crank and I cannot remember the flywheel shaft extending out on this side of the engine, only the other side where the drive pulley was. The picture even shows some sort of magneto. Notice the cylinder oil system. You would have to make sure there was oil in the cup and turn the valve when you ran the engine. If I remember correctly there was also a similar one on the crank too, or was it a grease cup like those on the main bearings, dunno.
This guy explains it a bit but on a much bigger one.