Overall rating
4 out of 5 (4/5)
The Kawasaki ZX-4RR is a lightweight sportsbike inspired by the ZXR400, which was one of the few ‘pocket rockets’ to be officially brought into the UK.
Back in the the late 80s and early 90s 250cc two-strokes and 400cc inline four-cylinder four-stroke ‘pocket rockets’, many of which were only sold officially in Japan were poster bikes. Inspired by 500cc GP racers and exotic Suzuka 8 Hour rocketships they were sharp-handling and lightning-fast for their size.
More desirable than the frumpy, big capacity sportsbikes of the day, the delicious collection of letters and numbers like Suzuki RGV250, Honda NC30, Yamaha FZR400RRSP and of course the Kawasaki ZXR400 will always be special for those of us who remember them the first-time round.
The 21st century version isn’t a remix of the original but instead based on the non-UK 2020 ZX-25R. Unlike the 90s version there are no choke switches, speedo cables or halogens here. Instead, the top spec RR (the only version to be brought to the UK) is fitted with niceties like a colour dash, LEDs, traction control and ABS.
For old crusties who fancy a slice of 90s pocket rocket nostalgia, or newer riders looking for their first step on the performance bike ladder the ZX-4RR delivers. There’s nothing quite like the undiluted joy of screaming a 400 to within an inch of its life. It’s fast without being intimidating and isn’t as gutless as you’d expect at low revs.
The real fun comes from by finding ways to eek out momentum through corners, which it’s brilliant at thanks to its nimble, balanced chassis and soft, but controlled suspension set-up. It’s physically small, but not as cramped as a Kawasaki ZX-10R or even the old ZXR400.
Ride quality & brakes
Next up: Engine
4 out of 5 (4/5)
The ZX-4RR doesn’t have fully adjustable forks or an ali frame like the old ZXR400, but it handles superbly. Suspension is on the soft side, which isn’t a bad thing as it adds to the ZX-4RR’s friendliness, but it’s balanced, easy to turn, stable and confidence inspiring. Brakes are superb with little ABS intervention at the limit and it comes on Dunlop GPR300 rubber.
A 400 is always going to be small, and the ZX-4RR is no exception. It’s the perfect size for the petit and less experienced, but pegs aren’t as high and bars as low as Kawsaski’s ZX-6R or ZX-10R or even the old ZXR400. Taller riders won’t find it too much of a squeeze, although it’s hard to get tucked in behind the low screen.
Engine
Next up: Reliability
4 out of 5 (4/5)
There’s no question the ZX-4RR punches well above its weight and every inch the pocket rocket. With a claimed 76bhp from its liquid-cooled 399cc inline four-cylinder engine pushing along 189kg the ZX-4RR has a superior power-to-weight ratio to Yamaha’s latest generation R7.
It doesn’t have its grunt, of course, making just 29lb-ft of torque at 13,000rpm. To put that into perspective Kawasaki’s ZX-6R produces 51lb-ft@10,800rpm and a Super Soco 125cc-equivalent electric scooter has 34lb-ft, delivered instantly. The ZX-4RR’s little engine needs all of its 15,000 revs for best results and it takes time for your brain to adjust to this sensational mayhem, but its bark is more savage than its bite.
That’s the joy of a ‘pocket rocket’. The Kawasaki is never intimidating or hard to control, but it’s quick, if you keep its 399cc inline four-cylinder engine singing.
You need to weld the throttle to the stop along the straights and adopt every trick in the book to stay in the power: tuck in tight like a Moto3 racer down the straights, lean over to stay on the small diameter part of the tyre under acceleration to lower the gearings and keep up your precious momentum going through the corners.
It’s a case of learning to release the brakes ever sooner and run, wide sweeping lines. It’s the opposite way of riding a big bike and so much more rewarding, not to mention easier on the mind and body.
Away from the engine’s manic scream zone the ZX-4RR isn’t as gutless as you’d imagine. Sticking it in a high gear at low revs isn’t the end of the world and it’ll canter along cleanly at normal speed.
Reliability & build quality
Next up: Value
4 out of 5 (4/5)
A machine like this will always be built down to a price, but it’s screwed together nicely and the ZX-10R-alike paintjob is thick (but wouldn’t it have been nice to see the old iconic green, white and blue graphics revived?). It’ll be bombproof when it comes to reliability, to the point that Kawasaki are initially offering a four-year warranty when the ZX-4RR arrives in dealers in October 2023.
Value vs rivals
Next up: Equipment
4 out of 5 (4/5)
Although it’s only a 400cc the ZX-4RR punches above its weight. Performance, price, weight and spec puts it firmly in among bigger capacity middleweight sportsbikes.
We’re talking Aprilia’s RS660 (£9650, 99bhp, 49lb-ft, 183kg), the Honda CBR650R (£8499, 94bhp, 46lb-ft, 208kg) and Yamaha R7 (£8910, 72bhp, 49lb-ft, 188kg). Of course, the Kawasaki’s engine isn’t anywhere near as flexible as its rivals, which makes it more of a one-trick pony, but what it lacks in grunt it makes up for with psychopathic hunger for revs.
In terms of bang for buck the Honda is still top dog, the Aprilia has the most power, but the ZX-4RR actually has a superior power to weight ratio than the more expensive R7.
Equipment
3 out of 5 (3/5)
Standard equipment includes a fully adjustable rear shock, preload adjustable upside down forks, radial monobloc front brake calipers, three-stage traction control, basic ABS, ride by wire, Full and Low (75-80% power) modes, up/down quickshifter, assist and slipper clutch, 4.3in colour dash with smartphone connectivity.
Model history & versions
Model history
2023: Kawasaki ZX-4RR launched. Arrives in dealers late ’23.
Other versions
Lower spec ZX-4R (not available in the UK).