Benelli 750 Sei
Benelli 750 Sei
. .Benelli's exotic six-cylinder superbike deserves a placein any history of fast motorcycles, despite one undeniable fact: by thestandards of mid-1970s superbikes. It wasn't outstandingly fast. The Italianmachine was undeniably stylish, sophisticated and expensive but lacked theoutright speed of the best Japanese superbikes and its Italian rivals alike.Despite this the Sei was a fine all-round performer, combining effortlessacceleration, remarkable smoothness and excellent handling in aneye-catching package topped by six gleaming chrome-plated exhaust mufflers.As well as being the only six-cylinder bike on the market when it waslaunched in 1974. The Sei also came with a pedigree. Benelli. Based at Pcsaro on Italy's Adriatic coast, had won the 250cc world championship asrecently as 1969, beating the two-strokes with a four-cylinder four-strokeridden by Australian Kel Carruthers.
Inspired by Honda
Apart from its number of cylinders, the Sei's 748cc engine containedlittle innovative engineering, and was not outstandingly powerful despite aclaimed peak output of 71 bhp at 8500rpm. Cynics commented that the SOHCunit was little more than one-and-a-half Honda CB500 motors. Like Honda'sfour it featured cylinder dimensions of 56 x 50.6 mm and a central camchain.Similar details such as the ribbed oil filter housing also revealed the maininspiration of the Italian firm's engineers. But the Benelli motoralso incorporated differences including its alternator, which sat not at theend of the crankshaft but behind the cylinders on the right, where it wasdriven by gears. That allowed the six-cylinder motor's crankcases to benarrow, as did the use of only three 24mm Dell'Orto carburettors, the outertwo of which fed angled inlet manifolds that allowed the carbs to be closetogether beneath the fuel tank.
The motor was tuned for mid-rangeperformance and was impressively tractable, producing useful torqueeverywhere above 2000rpm in top gear. Carburetion was crisp, and there wasbarely a step in the power delivery as the revs rose through the range. Thismeant that although the Benclli's top speed of about 115mph (185km/h) wasunexceptional, the bike impressed with its effortless high-speed cruisingability. Rapid riding was also boosted by a chassis that wasconventional in layout but which worked much better than most contemporaryset-ups.
The steel twin-cradle frame held Marzocchi forks, plus rear shockseither from the same firm or Sebac. Both ends were fairly firm in Italiansporting tradition. In combination with the reasonably rigid frame, thathelped give good straight-line stability. For a big bike the Benelliwas also impressively agile, and could be cornered faster than many muchsmaller machines. It had fairly generous ground clearance, especiallyconsidering its engine layout. Powerful twin Brembo front disc brakes,backed up by a rear drum, added to the six-cylinder machine's impressivechassis performance. Sadly for Benelli and particularly the firm'sboss, Argentinean car baron Alejandro de Tomaso, the Sei was not a saleshit. Despite its array of cylinders the Benelli lacked the character andperformance that made the best rival Italian superbikes popular. Potentialowners were worried about reliability and high running costs as well as thebike's considerable purchase price.
The Sei nevertheless remained inproduction with few changes until the end of the decade, when its engine wasenlarged to produce the 900 Sei. This had a little extra power and a neatheadlamp fairing, but no more charisma. It sold in similarly small numbersand marked the end. at least for the next quarter century, of Benelli'sattempt to become a major superbike manufacturer.
Source of review : Fast Bikes by Roland Brown