Tis a 750 Benelli Sei
The Benelli 750 Sei is a motorcycle that was produced by Italian manufacturer Benelli from 1972 to 1978. It was the first production motorcycle with a 6-cylinder engine. The engine was based on the four-cylinder Honda CB500, but with two extra cylinders. The cylinder head fins of the Sei were squared off to provide a cosmetic individuality, but otherwise the engine is in most respects obviously derived from the Honda. The "angular, bold design" was by Carrozzeria Ghia.
Despite the extra cylinders, the Sei's width was kept to a minimum by siting the alternator (which, on the Honda, is at the left-hand end of the crankshaft) behind the cylinders. Cooling was improved by having air passages between the cylinders; the Sei had three Dell'Orto VHB 24 mm carburetors (the Honda CB 500 had four, for four cylinders). After four years of production during which they sold 3,200 Sei models, Benelli developed the 750 Sei into a 900 cc motorcycle, with six-into-two exhausts, but built less than 2,000 of them.