Will Kawasaki's anticipated ZX-4R show the future for middleweight sports bikes?

The Kawasaki ZX-4R is reportedly on its way to Europe, but where would it fit in?

In motorcycling, there are distinctive categories, concerning the purpose of the bike, but also the displacement and power output.

For sports bikes, the general categories are currently changing. As a result of the lack of interest from the public in 600cc, four-cylinder sports bikes, manufacturers started making motorcycles with relatively similar potential but with fewer cylinders and higher displacement.

That has led to the introduction of bikes like the Ducati Panigale V2, MV Agusta F4 800, and Triumph Street Triple RS to the World Supersport class where they race more traditional 600cc four-cylinder middleweight bikes like the Yamaha R6 and Kawasaki ZX-6R.

The 600cc sports bikes are dying (or, at least the four-cylinder ones are), but perhaps there would be interest in a smaller version of one. That is what Kawasaki appears to be counting on with its ZX-4R.  

We already know with relative certainty that the bike will be an inline-four cylinder engine with a conventional firing order; essentially just like the old ZX-6R. But, of course, it will be smaller, so the power will be less, but the revs should theoretically be higher. 

That takes it out of the range of the ‘traditional’ 400cc bikes. Kawasaki already has a dog in this fight, of course, with its Ninja 400 that has won every WorldSSP 300 championship since Ana Carrasco’s 2018 triumph. 

The Ninja 400 produces around 44 horsepower from its twin-cylinder engine. It is expected that the ZX-4R will produce almost twice that power, and take its styling cues from the ZX-10R, with its aerodynamically vented fairing.

It sounds like an exciting prospect, because a screaming 400 is going sound incredible, and with perhaps something like 80 horsepower it should be, firstly, a lot of fun to ride, and, secondly, a bike that is relatively accessible for riders of even relatively low experience.

But, it will have essentially no competition. If it comes to Europe, it will be in a class, almost, of its own. It would be around 20 horsepower down on an Aprilia RS 660, but around eight horsepower up on a Yamaha R7. 

Both the RS 660 and R7 use twin-cylinder engines. Both produce 67Nm of torque, which would probably be more than the four-cylinder Kawasaki. At the same time the Kawasaki would probably be lighter, thanks to its smaller engine displacement.

Although we will have to wait for official information from Kawasaki, it is likely that these will be the sort of bikes the ZX-4R will be going up against, in terms of power, albeit with a different engine layout.

How competitive it will be against such competition also remains to be seen. Although the power will be similar, it will produce it at higher revs than the R7 or RS 660. That, of course, will sound better, but it will probably hurt the wallet more, too.

Either way, if and when Kawasaki eventually releases details about the new four-cylinder 400, it will be an exciting moment. If it works, it could be the start of something new in the middleweight sports category.

Top 10 Sports Bikes 2021 (Middleweight) | Triumph Daytona, Aprilia RS660, ZX-6R