Sixy beast
Benelli’s six-cylinder Sei gets transformed into a super-slick urban missile
If you want a truly unique custom bike, best pick a base model that’s as scarce as political integrity. Like Benelli’s Sei 900 – only 2000 of the air-cooled six-cylinder muscle bikes were built between 1979 and 1989. ‘We were very excited when a customer said he had one for us to work on,’ says Tiago Gonçalves, from Unik Motorcycles in Portugal. ‘He told us it was in bad shape, but the brief he gave us was excellent – the only thing he said was “I want it to be comfortable and I want six exhausts. You can do whatever you want with the rest”.’ Unfortunately the owner wasn’t kidding about the condition – the engine was a runner, but everything else was verging on scrap. Tiago and his team restored the frame and chucked the rest.
Most of the clever stuff happened at the rear of the bike, where the original swingarm has been replaced by a single-sider from a Ducati Monster S4R. ‘For me, this is the most beautiful swingarm there’s been on a production bike. But to get it aligned took a lot of calculations,’ Tiago tells Bike.
‘The original Sei had a 130-section tyre and now it’s
190 so to get it to line up properly we had to cut the rear of the frame by the footpegs – the whole tubular section – and then weld in a plate on each side. This gave an extra 10mm on one side and took 10mm from the other. The plates look original, but they’re not.’
With that done, you’d think adding a monoshock would be a doddle, but it didn’t turn out like that. ‘We had a lot of problems with this because it was difficult to get the perfect suspension movement. First we used a shock from a Honda, but the spring was too soft and the wheel hit the rear subframe. I talked to Öhlins, and bought a unit designed for a Triumph Tiger 800 because they thought the dimensions would work but it didn’t fit. In the end we fitted a harder spring to the Honda shock.’
‘The bike is a bit aggressive to ride,’ says Tiago.
‘There’s a lot of torque and all the gears are supershort, so acceleration is extreme. And it sounds like an old Lamborghini accelerating. When you’re riding, you really feel special.’
So special the owner rides it rather more than anticipated. ‘He’s already done over 1250 miles. He called the other day and said he’s going to ride it on a big trip. But we made half the aluminium fuel tank into a place to store the battery. And the fuel range is now just 45 miles. But he never told us he was going to go touring on it!’
‘There’s a lot of torque and all the gears are super-short’