This is the engine that started Briggs and Stratton. They bought the rights from Smith, then built their version of the motorwheel for a while, then adapted the same engine to stationary use. I've got one of each, but none of them running. very expensive to restore. The mag on the smith is a special small mag, they go on ebay for no less that $500. My uncle has a running Briggs, the same one he had as a kid in the 30's. He said he could pull another kid on a bike by holding on to the handlebars, up the Good Sam Hospital hill (Rif knows what I mean). If you look close the engine is hinged at the front so there's no problem going around corners.
Bob