A new patent from Honda hints that the firm could have plans for a new road-going single-cylinder sportsbike inspired by its 250cc Moto3 racer.
The patent is notable because it suggests a variety of different exhaust layouts for the unusual engine packaging used by Honda’s NSF250RW racer. Unlike normal bikes, the Honda racer uses a reverse-cylinder engine, with the intake at the front and the exhaust port at the rear. It also has a cylinder that tilts backwards rather than forwards.
While not unprecedented – Yamaha’s motocross models share a similar layout and BMW’s new G310R has now brought reverse-cylinder singles to the road-going market – the design is unusual enough to make it worthwhile patenting variations on the layout. In particular, Honda’s new patent focuses on the problem of making the exhaust system long enough, achieved by wrapping the pipe around the front of the cylinder before taking it back to the rear of the bike. Several variations are shown.
What’s unusual is that among the possible exhaust layouts for the Moto3 racebike Honda has also drawn up a version that includes a catalytic converter mounted transversely at the front just below the radiator.
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| Honda NSF250RW Engine |
There are two implications from Honda’s decision to develop a catalysed version of the Moto3 layout. One is that there’s a chance that MotoGP rules will at some stage be altered to introduce emissions limits. That’s not beyond possibility, since it’s important for motorsports to show environmental responsibility. The other thought is that Honda is considering a road derivative of its Moto3 racer.
Again, that’s plausible. The four-stroke Moto3 series was introduced in part to bring a closer connection between production bikes and racers, and there’s been a growing interest in small, 250cc sportsbikes in recent years. Honda itself is on the verge of launching an all-new twin-cylinder CBR250R, but could opt – as Kawasaki has – to offer both twin and single-cylinder 250-class sportsbike options in the future...