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Benelli 750 Sei
The Benelli 750 Sei was the first production motorcycle with a 6-cylinder engine and had two model releases. De Tomaso intended it to become Italy's premier sporting motorcycle and wanted it badged as a Moto Guzzi. On its launch, it received tremendous publicity overshadowing all other Italian bikes of that year. It started the trend of angular designed motorcycles moving away from traditional round forms.
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. It produced 96 bhp at 9,000 rpm, had a top speed of around 127 mph and was one of the smoothest European tourers.
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). The vehicle appeared to reviewers as heavy and cumbersome but handled surprising well, and had a unique signature exhaust note from its six mufflers.
The Benelli 750 Six remained the only six-cylinder motorcycle in production until the entrance of the Honda CBX in 1978.