In the 1960's, John Taylor of Schenectady, New York decided to begin building in the United States, a dual-purpose motorcycle, that would not only compete with European enduro-type motorcycles, but excel by being more powerful, better built, more reliable, and faster. Below is a picture of a 1971 Yankee Z motorcycle. It's 100% original, right down to the "Full Bore" tires. There were only about 760 of this model built by Yankee Motor Company back in the early '70's.
The concept for the engine had been designed by Eduardo Giró of the OSSA factory in Barcelona, Spain. The engine was actually a joining of two single-cylinder, 2 cycle, air-cooled engines into one torquey twin with a common crankshaft and cases. Although the engine was designed primarily for the roadrace courses of Europe, Eduardo wanted this engine to offer versatility for both road and dirt use. The engine could be made to fire with both pistons together, as a large single cylinder engine would and, with a relatively easy method, be made to fire with each piston taking its turn at the top of the stroke, as most twin-cylinder engines of the time did.
Originally, it began with the OSSA 230 cc. engine cylinders, pistons, and crankshafts, but by the time the motorcycles were actually produced, the OSSA became a 250 cc, and therefore, the Yankee became a full 500 cc twin.
Follow the full story by clicking the link to this beautiful website : http://www.yankeetwin.com/
Photos below courtesy of Jim Small