The long saga of Suzuki's efforts to develop a new 700 cc parallel twin that will form the basis of the next generation replacements for the SV650 and V-Strom 650 has reached another milestone with the release of a patent that provides insight into a completely new machine that is created around the same engine. The “concrete” result could be an SV ready to play with the Yamaha MT-07.
First proposed eight years ago with the Recursion, a supercharged concept bike presented at the Tokyo Motor Show in 2013, Suzuki's idea for the development of a new parallel twin has been revived over the years through numerous patents filed by the Japanese factory. Initially, the Recursion was equipped with a turbocharged SOHC parallel twin with a displacement of 588 cc. Back in 2015, the company had rethought this idea, showing off its turbocharged XE7 parallel-twin engine – a DOHC design of around 700 cc – and it was this project that has since been pursued by the company's R&D department.
The advantage of the parallel twin is that it offers a cheaper but also more compact alternative to the V-twin layout that Suzuki currently favors on the SV650 and V-Strom 650, and an alternative to the inline-four. There are fewer components overall, and compared to V-twins, integrating the engine into the chassis is simpler, with no rear cylinder to add complexity to exhaust gas routing, the rear cylinder cooling and rear suspension integration.
Parallel twins also have their own disadvantages, starting with an uninspiring sound and fairly hollow power. These are easily countered by using a 270 degree crankshaft to give a firing interval that matches a 90 degree V-twin. To name a few, the BMW F900, Honda Africa Twin and NC750, Triumph twins, Yamaha 700 and Aprilia 660 all opt for a 270 degree timing in order to achieve power and sound similar to the V-twin.
The latest patent differs from previous ones, showing an unusual arrangement of the air box to prevent it from intruding into the fuel tank area. In previous designs, including turbocharged and non-turbocharged versions of the new engine, the airbox was located above the cylinder head, below the tank, with an intercooler on the turbo machine. This allowed a very direct passage of the air pipes on the turbo version, but clearly limited the potential size of the tank.
The new design is based around an air box placed under the rider's seat, where it serves double duty by also providing a support platform for the battery. Unusually, the layout means the air intakes face rearward, eliminating any potential dynamic effects, but the patent emphasizes that the sacrifice is worth it as it allows the airbox to be much larger than it would be if mounted under the fuel tank, potentially giving a greater performance advantage.
With an increasing emphasis on ease of maintenance, especially in a market where maintenance costs can be a deciding factor, the underseat airbox design also allows for air filter replacement without removing the tank.
With the Suzuki parallel twin project having been under development for nearly a decade, it is still unclear how soon we will see the engine appear on a potential replacement for the SV650. As for the turbo version, that is also a question mark as of now.
