Classic Cars, Trucks, and Motorcycles - History, Pictures, and Information



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First Six-Cylinder Motorcycle


Both automobile and motorcycle manufacturers have experimented with six-cylinder engines since at least the 1920's.


In 1964, Honda produced the first of several RC-series bikes, a 24-valve, straight-six cylinder motorcycle made exclusively for GP racing. It's 249cc size was made from a 39mm bore and a 34.8mm stroke.


Honda's RC166, produced in 1966, was also 249cc, but used a bore and stroke of 41 mm and 31 mm. The following year saw the 249cc RC167, followed by the 297cc RC174 (41 mm and 37.5 mm) which raced in the 350cc class. The Honda RC-series bikes were never offered for sale to the public.


The first and smallest-sized production straight-six cylinder motorcycle was the Benelli 750 Sei, which displaced 747.7 cc.



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Benelli SEI


Benelli Sei 750 image Although priced higher than its Japanese competitors, both the 750 and 900 SEI offered riders European flair with solid performance. Compared to the Honda CBX-1000 or the Kawasaki KZ1300, the bike did not feel bulky or overweight. Although it did not have a racing pedigree like Ducati's 900SS, it was a simple, stylish bike that had good road manners, making it a classic Italian motorcycle in it's own right.



The coastal village of Pesaro, Italy, is where the six Benelli brothers started building motorcycles in 1921. During the second World War, much damage was done to Italian factories. It took until 1949 for Benelli to get back to production, manufacturing pre-war-based models. With their country in upheaval and gasoline costing $4 per litre, their small, inexpensive single-cylinder bikes sold well. Business prospered throughout the Fifties and early Sixties.


By this time, the U.S. had become one of their biggest markets, and like other European motorcycle manufacturers, sales began tapering off when the bigger and more advanced Japanese motorcycles, like Honda's CB750, arrived in the late Sixties. In comparison, the bikes that Benelli were producing were 350cc or smaller, with engine designs decades old.


Using the popular British vertical-twin engine as a template, Benelli's first large bike was the Tornado 650. Introduced in 1967, it produced 50 horsepower, featured a five-speed gearbox, and had four-shoe front braking. Top speed was over 110 mph. Well-received by critics and priced less than its competitors, the Tornado should have been more successful. However, due to tooling issues and management conflicts, it's release was delayed until 1969. The Benelli Tornado and Tornado S were produced until 1974.


With overall sales continuing to fall, the Italian firm was acquired in 1973 by industrialist Alejandro de Tomaso (of mid-engine sports car fame), who quickly launched a full-scale campaign against Japanese motorcycle manufacturers. Benelli's first modern multi-cylinder bike, the 500 Quattro, was an in-line four with dual overhead cams, chain drive and a five-speed transmission. It was built in response to Honda's CB500, which it resembled in many ways, including bore and stroke.


Benelli SEI 750cc


'The Italian Alternative' was Benelli's advertising slogan in the Seventies Although completed in 1972, internal issues within the company prevented the SEI (Italian for six) from being released until 1974. Essentially an inline-four 500cc engine with two extra cylinders, the girth of the inline six was narrowed by moving the alternator off the left side of the motor and mounting it behind the cylinders. With three Dell'Orto carburetors, the engine produced around 70 horsepower and was capable of 120 mph. A pair of front disc brakes supplied dependable stopping power. Adorning both sides of the bike was a trio of chrome mufflers, complimenting the overall lines, as well as showing off it's abundance of cylinders. At 560 pounds, the bike was heavier than comparable machines, but its solid frame and suspension gave the rider confidence in high-speed cornering.


Benelli SEI 900cc


Benelli Sei 900ccIn 1978, the SEI was bored and stroked to 906cc. 125 mph top-end speeds were now obtainable, and cruising speeds were at lower rpm's. Styling changes included a small, fork-mounted fairing wrapped around the gauges, with the fuel tank now hidden beneath outer panels. Spoked wheels were replaced by cast wheels, and a more conventional six-into-two exhaust system replaced the original style. The rear drum brake was replaced by a disc unit.



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Japan's Six-Cylinder Bikes


Benelli had surpassed the Japanese in multi-cylinder bikes, until 1978, when Kawasaki introduced their six-cylinder bike, the KZ-1300. The KZ was a complex, sophisticated machine, weighing over 700 pounds, with an output of 120-horsepower and 85 ft/lb of torque. Road tests of the era showed the big Kaw topping 140 mph, with quarter-mile times under 12 seconds. The following year, Honda introduced their six-cylinder bike, the twin-cam, 24 valve CBX-1000. At 600 pounds, the CBX was lighter than the KZ, producing a smooth 105-horsepower, and had recorded 11.36 seconds in the quarter-mile. Both the KZ and the CBX morphed into sport/touring bikes.



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