Kawasaki Ninja ZX-4R and ZX-4RR 2024 Launch Review

At first glance, the idea of Kawasaki’s Ninja ZX-4R and ZX-4RR supersport 400cc motorbikes seems incredibly brave considering they aren’t learner-approved and have an RRP upwards of $11k. But the more I unpack it, the more I see the substantial gap that exists between most LAMS bikes and true full-power supersport machines.

Japanese 600cc supersport bikes retail for close to $20,000 these days, and they’re a pretty big step up from the learner-friendly 400cc offerings. To dabble in track riding or racing for less than $15,000, you’ve got to take a gamble on the used bike lottery or settle for something with less performance. Kawasaki’s ZX-4R and ZX-4RR supersport machines should help fill this small but obvious void nicely.

Sliding into Kawasaki’s supersport range (which includes the ZX-6R, ZX-10R, and ZX-14R), the Ninja ZX-4R and ZX-4RR KRT Edition retail for $11,794 and $13,194 respectively (plus on-road costs). The extra $1400 for the KRT Edition RR will get you upgraded suspension, a bi-directional quickshifter, and Kawasaki Racing Team-inspired livery.

While the ZX-4R and ZX-4RR are not in direct competition with most of the current LAMS 400cc offerings, it’s worth noting the substantial price difference of around $3000 to $4000 (depending on model comparison).

But, if you compare the ZX-4R/RR with the Ninja 400, there is a big difference in performance and overall package. For example, the ZX-4R/RR models boast 74.8hp (55kW), high-grade suspension, and a plethora of premium features, whereas the Ninja 400 puts out 47.6hp (35kW), with relatively basic suspension and technology.

Team Green is bringing back the scream with its newly designed, quick-revving 399cc liquid-cooled inline four-cylinder engine that has a redline north of 15,000rpm and Kawasaki’s Ram Air system. It is dripping in superior, lightweight components that are usually reserved for Kawasaki’s premium high-performance models.

As mentioned, the 399cc engine produces a claimed maximum output of 74.8hp (55kW), the figure chiming in at 14,500rpm, but the Ram Air system pushes this a smidge further to 77hp (56.7kW). Claimed maximum torque is 37.6Nm at 12,500rpm.

Similar to the layout on the Ninja H2, the Ram Air duct is routed to the left of the front fork on its way to the airbox. This enables highly efficient airflow of cool, high-pressure air to be ingested from the front of the bike, while side air ducts built into the fairings direct cool air into the engine room.

If the engine specs don’t convince you that the ZX-4R and ZX-4RR have more in common with their larger supersport and superbike siblings than they do with most other 400cc motorbikes, then the running gear most certainly will.

For starters, the Showa SFF-BP (Separate Function Fork – Big Piston) 37mm inverted fork is something you’re more likely to find on a 600, and the ZX-4RR has adjustable spring preload, which up until now is virtually unheard of in the 400cc class.

The rear suspension on the ZX-4RR KRT Edition is much like what you’ll find on the Ninja ZX-10R. The horizontal back-link rear suspension is positioned above the swingarm to minimise the effects of heat from the engine and exhaust. Spring preload, compression and rebound damping are all adjustable, and all suspension is tuned with comfort in mind for the daily commute, combined with strong support for reassuring chassis stability on the racetrack.

The bones of the ZX-4R/RR comprises a compact high-tensile steel trellis frame with a hollow, reinforced swingarm pivot section. Capitalising on its knowledge from World Superbike racing, Kawasaki says it has been meticulous in achieving the right balance between strength and flexibility by varying steel thickness and diameter.

The assist and slipper clutch comes straight from the racetrack too, offering both a light feel at the lever while limiting back-torque during aggressive downshifts.

The braking package comprises twin semi-floating 290mm discs with radial-mount, four-piston monobloc calipers up front, and a 220mm disc with single-piston caliper at the rear, all backed by ABS.

The lightweight five-spoke alloy rims come wrapped in a set of Dunlop GPR300 radial tyres (120/70ZR17 up front, 160/60ZR17 at the rear) that are known for their performance and agility.

Complementing the good looks and performance is an equally impressive electronics package. The 4.3-inch TFT colour instrumentation adds a high-tech vibe and offers a circuit mode, which puts the lap time in the centre of the screen and makes gear position and the tacho more visible. It also features smartphone connectivity via a Kawasaki app. The key cylinder contains an immobiliser while the bikes also score a full LED lighting package.

A choice of ride modes include three levels of traction control and two levels of power. There are three preset ride modes, as well as a customisable mode.

Sport mode offers full power and the least intrusive level of traction control. Road mode offers full power and additional traction control intervention. And Rain mode has low power and the most intrusive level of traction control.

Users can use the custom mode to create their own combination of settings while the traction control can also be switched off completely.

Intent on showcasing the ZX-4R and ZX-4RR’s track finesse, Kawasaki held the Australian launch at Morgan Park Raceway in Queensland. We were greeted at the track by a beaming Kawasaki crew, who had just spent the morning running the bikes in for us. With near perfect weather and track conditions on our side, we were able to cut laps all day, becoming very well acquainted with these entry-level supersport bikes.

Throwing a leg over instantly confirmed that these bikes feel as good as they look. With an 800mm seat height, I was able to sink into the cockpit and touch the ground with ease. The riding position is what I would term, 'comfortably aggressive'. The TFT dashboard clearly displays everything you need to know and more, and navigating the functions is a straightforward exercise.

Clutch action is lightweight, and gear engagement is silky smooth. The throttle response is instantaneous and there's sufficient low-rpm power for painless slow-speed manoeuvring.

Rolling out of pit lane with nothing but clear racetrack ahead, the finely tuned 399cc engine insisted that we keep it well above 10,000rpm if a good time was to be had. While power delivery is very linear, anything below 10,000rpm lacks oomph, especially if you’re expecting the acceleration to match your wanton throttle behaviour.

Maximum power is at 14,500rpm (dropping off before the 16,000rpm redline) and you betcha, it feels as good as it sounds when you keep it singing there. And it sounds good! Even with the stock muffler and catalysers, these babies let off a tremendous high-pitched howl.

Getting busy with the six-speed gearbox is necessary, so I was grateful for the harmonious relationship between the gearbox and feather-light assist and slipper clutch. After a session on each model, I developed an absolute bias towards the bi-directional quickshifter on the ZX-4RR KRT Edition. Its seamless operation adds a huge layer of joy to an already awesome bike.

The suspension, chassis and brakes are a winning package, ensuring these machines are very easy to ride fast. We only tested them in prime conditions, but the Dunlop GPR300 tyres were hard to fault. They stuck like glue during cornering and provided terrific high-speed stability and performance under heavy braking.

The twin discs up front offer ample braking performance. I did experience some rear wheel skipping while vigorously downshifting and braking, but in general the ZX-4RR felt perfectly composed. I also noticed some intrusion from the ABS through the front brake lever but again, this was no big issue.

Tipping into corners is a breeze and you can snap the throttle open early on without consequence. Same goes with choosing a line: the ZX-4R and ZX-4RR will tenderly forgive your mid-turn change of heart. They really are highly intuitive machines, with plenty of zing.

Straight out of the crate, both the ZX-4R and ZX-4RR are track-ready bikes that will also do the commute no worries. The ZX-4R is available in Black, while the ZX-4RR comes in Lime Green/Ebony with KRT livery.

The upgraded suspension on the ZX-4RR is noticeable on the track, but probably not so much on the road. The quickshifter is awesome, and you can add it to the ZX-4R for around $590 (plus installation).

Add-on accessories include a smoked windshield, pillion seat cover, frame sliders, tank bag, tank pad, radiator screen, helmet lock, smart bag and wheel rim tape.

Kawasaki has put its money where its mouth is with these models. The ZX-4R and ZX-4RR are both stunning, well-mannered motorbikes with impressive track capability.

Ergonomically superb for small to mid-size riders, their high-revving engines give a good dose of performance, while their chassis, suspension, and brakes provide expert handling and precision. Quintessentially Japanese, these small-displacement supersport machines are bringing back a niche many of us thought was gone for good.

ENGINE
Type: Liquid-cooled, four-stroke, DOHC, 16-valve, inline four-cylinder
Capacity: 399cc
Bore x stroke: 57.0 x 39.1mm
Compression ratio: 12.3:1
Fuel system: Electronic fuel injection
Lubrication system: Forced lubrication, wet sump
Starting system: Electric
Ignition: Digital

PERFORMANCE
Claimed maximum power: 75hp (55kW) at 14,500rpm
Claimed maximum power with Ram Air: 77hp (56.7kW) at 14,500rpm
Claimed maximum torque: 37.6Nm at 12,500rpm

TRANSMISSION
Type: 6-speed return
Final drive: Chain
Clutch: Wet multi-disc, assist and slipper

CHASSIS AND RUNNING GEAR
Frame type: High-tensile steel trellis
Front suspension: Showa SFF-BP 37mm inverted fork, adjustable for preload, 120mm wheel travel
Rear suspension: Showa BFRC Lite horizontal back-link monoshock, fully adjustable, 112mm wheel travel
Front brakes: Twin semi-floating 290mm discs with radial-mount, four-piston monobloc calipers, ABS equipped
Rear brakes: Single 220mm disc with single-piston caliper, ABS equipped
Tyres: Front – 120/60ZR17M/C (58W); Rear – 160/60R17M/C (69W)

DIMENSIONS AND CAPACITIES
Rake: 23.5 degrees
Trail: 97mm
Claimed wet weight: 188kg
Seat height: 800mm
Wheelbase: 1380mm
Fuel capacity: 15L

OTHER STUFF
Price: ZX-4R – $11,794 plus on-road costs; ZX-4RR KRT Edition – $13,194 plus on-road costs
Colours: ZX-4R – Black; ZX-4RR KRT Edition – Lime Green/Ebony