So advanced was Edward Turner's original square-four design that 45 years later when Suzuki needed a new motor to go up against the established leaders in 500cc Grand Prix racing, they dusted off the concept and created the RG500, twice world champion in 1975-76. Basically two parallel-twins mounted one in front of the other in a common crankcase, the square-four has the advantage of being nicely compact, neither as wide as a transverse inline-four, nor as lengthy as one situated longitudinally. With counter-rotating crankshafts it also has the benefit of being nearly vibration-free, appreciated whether you're chasing GP titles or pulling a sidecar on tour.

This Square Four from the Lattin collection, a "twin-piper" displacing 997cc, is equipped with the alloy head and barrels that first became available in 1949, dropping about 30 pounds compared to the previous cast-iron cylinder assembly. The bike is presented in complete and original condition, and was reporedly a very good running bike during Lattin's ownership. As with all the machines in the collection, a safety check and recommissioning is in order before the bikes can once again take to the road.

Without Reserve