NCCR Rotax/Buell 'Helicon' SuperSingle
It has been nearly 30 years since Ducati's legendary but limited-production Supermono demonstrated the potential of converting a V-twin engine into a balanced single-cylinder - and now Swedish company NCCR is performing the same trick on the Rotax-made Buell Helicon engine.
The Helicon was the basis of the final generation of original Buell machines, including the 2007-on 1125R and 1125CR, and went on to form the basis of the Erik Buell Racing 1190 models that emerged from the ashes after Harley-Davidson closed Buell in the wake of the 2008 financial crisis, with power ranging from 146 hp to 185 hp. By turning it into a single, with an initial capacity choice of 562 cc or 595 cc, depending on whether it's based on the 1125 or 1190 Helicon, NCCR expects around 70 hp, with the option to increase that to 90 hp with a planned big bore kit to raise capacity to 660 cc - 700 cc.
Why build a single from a V-twin? The answer today is the same one that Ducati explored in its 1992 Supermono: the unused cylinder forms the basis of a balancer mechanism to eliminate the usual single-cylinder vibes. In simplified terms, the piston and cylinder are removed and the conrod is bolted to a pivoting balance weight mounted in a new casting that bolts on where the cylinder should sit.
It's a balance system that worked not only on the original Supermono, but more recently on BMW's parallel twin models, which have a rocking balancer below the crankshaft.
The NCCR engine isn't simply a Ducati Supermono copy, though. The initials stand for Northern Classic, Custom and Race, and NCCR was EBR's European partner. The company also looks after the original EBR WSB race bikes, as well as EBRs that competed at Macau and the IoM TT.
To create the first SuperSingle, NCCR has opted to remove the V-twin's front cylinder, where Ducati sliced off the rear one. The result is a backward-leaning single-cylinder with a reverse cylinder head - intake at the front, exhaust at the rear. It's an unusual layout, but not unique; Honda's Moto3 race bikes use the same rear-leaning, reverse head idea, as do certain Yamaha motocross bikes and BMW's single-cylinder G310 models. However, there's little reason that the same kit of conversion parts couldn't be used to remove the rear cylinder and keep the front one if the layout works better for some applications.
Jens Krüper, co-founder of NCCR, explains: "The SuperSingle concept gives us some great opportunities, like positioning the working cylinder front or rear, depending on which weight distribution you are looking for. Modern standing Enduro riding styles always generate bad rear wheel traction, that's why we use the rear cylinder position for our first build now. It also gives us excellent packaging possibilities to protect other components like the radiator and the exhaust system.
"Imagine how reliable that engine will be - three litres of oil plus a clutch and gearbox that can easily handle more than double of the power we're aiming on. The Helicon is a very reliable and long-term proven engine platform. The engines are fairly cheap to find, and last but not least, we have more than a decade of experience with it."
NCCR is initially building the engine into a 'travel enduro' demonstrator, but also envisages a future for the engine in a Sound of Singles race machine using the big bore version of the Helicon based unit.
Birgit Krüper, CEO at NCCR, explains that the company will make the engines available along with chassis kits, and may even offer complete machines: "We see a clear business opportunity in developing the SuperSingle engine concept. In times when most bikes get heavier and heavier and have more and more technology on board, a light and simple but rugged and reliable set-up will have its market. With making engine and chassis components available, we plan to support cost- friendly individual bike builds."
