Kawasaki is working on a supercharged four-cylinder bike as a replacement for the mighty ZZR1400.
A flurry of new patent documents from the company show enough detail to suggest the idea of supercharging a new high-performance machine is far more than just an engineering exercise.
Recent power increases in 1000cc superbikes, exemplified by the 190bhp BMW S1000RR, have created a problem for super-fast sports tourers like the ZZR1400 and Suzuki Hayabusa. Once the final word in flat-out acceleration and top speed, they are now outperformed by lighter, nimbler superbikes in a straight line as well as around corners.
The solution? Take advantage of the fact the ZZR has no race regs to conform to and add a huge dollop of power with the addition of a supercharger.
Over the last few weeks no fewer than four patents have been published, all showing different aspects of the same ZZR1400-style supercharged bike. But don't rush out to place your order just yet - Kawasaki is believed to be working on a revised ZZR, so a supercharged machine is likely to be at least 18 months away.
The design neatly slots the supercharger itself just behind the cylinders, underneath the throttle bodies, with drive to the turbine supplied via an idler gear (to increase its speed relative to engine revs) and a short chain. Air coming in through the normal intake between the headlights runs through a filter, over the engine and down to the supercharger, where it's compressed before being fed back up to the throttle bodies. There's no provision for an intercoooler, suggesting the set-up is aimed at providing a relatively modest power and torque increases, rather than drag-strip boost figures.
When it comes to supercharging, Kawasaki isn't breaking new ground; the firm already has years of experience with a remarkably similar supercharged four-cylinder engine. Not on a motorcycle, but in one of its jet skis. The Ultra 300X uses a motorcycle-style DOHC, 16-valve, four-cylinder engine, fairly close to the ZZR1400's in dimensions although with a slightly larger 1500cc capacity. In a bike doing without the Ultra 300X's intercooler around 250bhp should still be within easy reach.
Suggestions of a supercharged ZZR first emerged in 2009, however, this is the first time we've seen hard evidence to substantiate the rumours. The bike's relatively low development costs - adding forced induction to boost performance is a far cheaper way to boost performance than developing an entirely new motor - make supercharging the ZZR a promising prospect for a strong power-to-money ratio.