Above is a video of a rather unusual old engine designed for use on farms. Its called an ignitor fired engine because it has rods mounted on its piston which, powered by a magneto, cause the spark to start the combustion cycle.
It was a two cylinder engine, although it could be ran using only one of the cylinders. After the two cylinders fired there would be a one and a half rotation of the flywheel before another combustion cycle.
I couldn't find a lot of information about it. I did find a nice webpage, The Edwards Two-Banger Project, which details the restoration of a spark plug version of the Edwards engine. It has a lot of photos and they give a pretty good view of how the mechanisms of the two cylinders are mechanically isolated from each other, which allows the engine to run on one cylinder.
An odd little engine. Nobody is too sure how many were made, but there seem to be a number of restored versions of them being shown on YouTube, so they weren't a complete rarity.
|Ad from The Edwards Two-Banger Project (click to enlarge)|