There’s something strangely alluring about six-cylinder motorcycles. Despite the fact that they are heavy, more costly to maintain and seldom offer better performance, those extra cylinders seem the ultimate indulgence.
In the late seventies, Benelli was on its knees. Japanese motorcycle manufacturers had muscled in on the market and 4-cylinder machines like the CB750 and Z1 looked set to ruin the aspirations of many European and British marques. Benelli had been too slow to evolve. Its technology was outdated and outgunned and they needed a solution fast. So, in 1971, Alejandro de Tomaso, who was known for his race cars and the acquisition of several Italian automotive brands, purchased Benelli and promptly set its staff an ambitious task.
Tomaso instructed Benelli’s engineers to dismantle and study Honda’s CB750 inline-four and to use what they found to design a new Benelli offering. The result was the 4-cylinder 500 Quattro of 1971. The following year, after the success of the Quattro, Benelli repeated the process using a CB500 engine but added 2 additional cylinders for effect. The Benelli 750 Sei became the first production 6-cylinder and a few years later it evolved into the 900 Sei.
The Benelli 900 Sei had a unique signature exhaust note from its six-into-six exhaust, a slim profile thanks to the placement of the alternator and modern angular styling. Combined with its 6-cylinder offering it was a revolutionary machine that took Europe by storm and helped to resurrect the failing brand.
When Tiago and Luis of Lisbon’s Unik Edition Motorcycles were tasked with rebuilding a 1979 Benelli 900 Sei they didn’t take the task lightly. Inspired by the sound of the legendary Italian six-cylinder they named the project “sinfonia” (symphony) and spent 12 months creating one of their most ambitious builds to date.
“It was a very challenging project,” says Tiago. “Basically we were given an engine and a frame which meant that everything would have to be redone again.” With the frame and engine came a basic, yet challenging brief of building a bike that was easy to ride. So using their extensive knowledge and impressive skill set the redesigned the 900 Sei from the ground up.
First came the task of getting the bike rolling again and handling right. To do this a whole new suspension and wheel package was put together using modern equipment. The rear end was the biggest challenge. With the aim of moving away from a twin-shock design to a mono-shock, the Unik team acquired a Ducati S4R single-sided swing arm. But installing it was no laughing matter. To make the transition possible the rear half of the chassis has been heavily modified. The subframe is all new and its design includes a fixing point for the centrally mounted shock. Heavy modification also had to be done to fit the swingarm into the frame and then to properly align the chain and sprockets so that everything ran run true.
To ensure the front end wouldn’t be outperformed by the rear, Unik has fit the Benelli with a modern USD set of sport bike forks. The forks sit in a custom-made triple tree which wear LSL handlebars to set up an upright, super naked style riding position. Both wheels have been built using striking Kineo rims and are wrapped in purposeful Pirelli Diablo Rosso 2 rubber. Leaving no stone unturned Unik also created a custom brake package for the Benelli with twin disc 6 pot calipers in the front and the rebuilt Ducati S4R disc at the rear.
Since the donor for the project came devoid of bodywork, Tiago and Luis had to create something entirely new. Their goal was to make a modern yet timeless design that took cues from Benelli’s original work. The factory 900 Sei wore bodywork designed to look like a monocoque structure and similar to many modern bikes, the fuel tank was a cover that concealed a steel fuel cell. Taking the lead from Benelli’s approach the boys fabricated an aluminium fuel cell and oil tank. They then shaped a one-off monocoque body from carbon fibre that sits over the tank and mounts to the modified subframe. A modest tuck and roll saddle provides seating for one and a Monza-style filler completes the retro aesthetic. To wrap up the new look the bike also wears a custom-made headlight housing and the modern fender that came with the new front end.
Of course, the star of this build, the 906 cc 6-cylinder engine, didn’t go untouched. After a thorough service and clean, Unik freed up its respiratory system by installing cone filters on to the 3 Dell’Orto carbs and fitting a spectacular pie-cut 6-into-6 stainless exhaust system. Despite its size and configuration, the 900 Sei produced a modest 76 bhp but now with a fistful of additional horses freed up and a lot less weight to haul around, this bike is sure to provide a much more exhilarating ride.
Completing this extensive transformation is a gamut of modern aftermarket parts. These include comprehensive electronic gadgetry upgrades from the Motogadget catalogue as well as Motogadget bar end turn signals, grips, glassless mirrors and a keyless ignition. The headlight is a modern LED unit and the tail features an integrated retro lens packed with LED internals. Finally, to wrap up the new look, Unik has finished the bike in classic Italian-inspired livery with a touch of cafe racer style in the form of a checkered motif down the spine of the tank. Tiago tells us “We are very happy with the result” and it’s plain to see why.