Insiders tell us this is a prototype for Suzuki’s return to MotoGP in 2014. The project was, we are told, “hot for a while” and then cooled off. Now, with these photos from a test earlier this month at Sugo Circuit in Japan, it clearly has momentum again.
What have we here? We see from the exhaust pipes that this is a transverse inline-Four, just like all GSX-Rs. That is a departure from Suzuki’s V-Four GSV-R MotoGP architecture. While the usual pipe arrangement for a flat-crank inline-Four is 4-into-2-into-1, this bike has two long-taper megaphones, each connecting to a pair of cylinders. That suggests this engine does not have a flat crank but instead is fitted with a 90-degree “crossplane” crank shown by Yamaha’s engineer Masao Furusawa to improve grip.
A Japanese informant said, “New Suzuki MotoGP racer is certainly inline-Four. It is not, however, normal inline. When guess from exhaust sound, kind same as YZR-M1.” All the other trappings of MotoGP are present: top-level Brembo calipers and carbon discs, Öhlins suspension, plus carbon-fiber bodywork.
What else do we see? We see a radically forward rider position, and that the engine’s cylinder block is inclined forward, perhaps as much as 30 degrees. This moves the intake throttle bodies to where they need to be in the airbox. As the rider accelerates (note that in one of the cornering photos, he has the throttle pinned, suggesting advanced electronics in use), his face is directly over the steering crown. The fuel tank sits behind a large carbon-intake airbox and consists of a thin forward vertical portion as tall as the airbox, with a long and quite thick “foot,” which effectively forms the rider’s seat. You can see fuel pipes to the injectors entering the front of the airbox. Note also that as the rider accelerates, his butt is three inches clear of the two-inch-thick seatback pad, further underscoring the far-forward rider position.
What has happened here is that as the engineers have sought to lower the placement of the fuel toward the machine/rider center of mass, putting most of it under the seat, fuel mass has moved rearward. If the front tire is not to become unweighted during off-corner acceleration, something else must compensate by being moved forward. And not only that, each year, as tire grip is increased, more power may be applied without wheelspin, increasing the tendency to lift the front.
Under the rider’s hands are bulbous ducts leading from the chin intake in the fairing nose, through the chassis sides and into the engine airbox. Although a rear-wheel starter can be seen in the garage shot, there is Suzuki’s usual round “starter door” in the right side of the fairing, through which a starter dog can spin the crank if the slipper-clutch setting is too soft to permit rear-wheel starting.
It’s hard to see what is going on with the airflow to the two radiators. At first, the “covers” between them and the front tire look solid, like carbon fabric. But they could also be stone shields. In one photo, the upper cover has come loose and moved forward along one edge, as if there were pressure behind it. If solid, it would be a first in ducting ram air from above the tire to the front faces of the radiators. Airflow behind the front tire is always disturbed, providing poor pressure to push it through the radiators. This is part of the reason radiators are as big as they are. Four large hot-air exit slots are provided in the fairing sides.
And when I look at where the cylinder head must be, it might suggest the upper radiator is U-shaped to make clearance for it. Suzuki did this during the early 1980s to move its disc-valve RG engines farther forward.
Recently on the Italian website GPone.com, journalist David Emmett asked Suzuki racing technical director Shinichi Sahara if the company will change to an inline-Four. Sahara replied that they will “stay faithful to our engine layout.” And in a Peter McLaren story from this past February, veteran Suzuki test rider Nobuatsu Aoki said he “rode it last week” at Ryuyo.
Conflicting information? Not at all. It is normal for manufacturers to build and test multiple prototypes before determining which is most promising. Veteran tuner Eraldo Ferracci has told of testing endless prototypes when he was at Benelli—and most were not produced.
There is also another possibility here: Suzuki is known for making multiple uses of projects, so an inline-Four MotoGP prototype could also gather information useful in design of next-generation GSX-Rs. Could such a machine also be the foundation for a production-based CRT bike? Might Suzuki build the MotoGP equivalent of a production racer in the spirit of Yamaha’s TZs of the 1970s?
It’s a guessing game, and we enjoy it. We shall have the pleasure of anticipation.