First Ride: 2023 Kawasaki Ninja ZX-4RR (2024)

Small-displacement four-cylinder motorcycles have developed a sort of cult following over the years. Only a handful of sub-400-cc fours have trickled into Canada over the last few decades, and their high-revving engines, light weight, nimble handling, and exclusivity have made them desirable among collectors. We’ve seen just a few models from Honda, Suzuki, and Yamaha come here, but none from Kawasaki.

That is, however, until this year, with the introduction of the 2023 Kawasaki Ninja ZX-4R and ZX-4RR. Here we’re focusing primarily on the latter, on which we spent a day riding at the technically challenging Thunderhill Raceway Park in California, though we also rode the 4R briefly on the road.

Like its bigger Ninja stablemates, the ZX-4RR features aggressively angular styling, and a nose-down, ready-to-pounce attitude. Unlike its supersport brethren, however, which are all built around aluminum frames, the ZX-4RR utilizes a steel-trellis frame design. It also boasts a slightly more relaxed riding position that is roomier than one would expect from a 400-class bike.

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The frame cradles a 399-cc liquid-cooled inline-four that is controlled by ride-by-wire EFI. This system enables four selectable ride modes, and two power modes: Low, with soft throttle response and limited output; and High, with a more aggressive throttle and full power. Three of the ride modes feature preset traction-control intervention, from high to low; and for the race track there’s a configurable “rider” mode, in which engine parameters can be set independently and traction control can be turned off. Maximum power is slightly neutered, however, but more on that later.

A 4.3-inch TFT colour display comprises the instrument panel, through which ride modes are selected. You can connect to your smartphone via Bluetooth and use Kawasaki’s free Rideology the App to access various display functions remotely. The instrument cluster has two possible display layouts — Normal and Circuit — with Circuit highlighting gear position, revs above 10,000 rpm, and button-triggered lap times (GPS-enabled lap times are recorded through your smartphone).

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The 4RR has a couple of track-friendly features above the standard 4R model, including suspension that is adjustable for spring pre-load in the front and fully adjustable in the rear (only rear-spring pre-load is adjustable on the R model) and a quick shifter that permits clutch-less shifting up and down the six-speed gearbox (no quick shifter on the R).

These additional features bump the RR’s price to $10,999, or $1,000 more than the R model, but after spending a day on the track, I can attest the RR is worth the added premium. Also included on both models is a mechanically assisted slipper clutch that has a light pull and helps prevent wheel-hop when decelerating from high speeds.

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The ZX-4RR felt immediately comfortable at speed on the track, with light, neutral, steering through the tighter turns, and confidence-inspiring stability on the fast straights and long sweepers. The suspension was initially a bit too soft for my 200-lb carcass, with the bike wallowing a bit exiting turns. But a quick adjustment between sessions for added pre-load at both ends and some increased damping at the rear remedied this, and the bike felt remarkably tight. Despite rolling on a steel frame, the ZX-4RR’s chassis proved rigid and highly competent on the track. The bike even rode over a particularly bumpy portion of the racetrack at full throttle without the slightest tinge of headshake.

Manufacturers usually install sticky race tires for track tests, but Kawasaki chose to let us loose on the OEM rubber. The Dunlop Sportmax GPR-300 tires provided very good grip and feedback, even at maximum lean, and only gave up some of that grip when approaching a nine-tenths pace.

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The brakes provided excellent stopping power, with good feel and feedback, though the absence of a track mode for the ABS meant that it sometimes triggered when entering a turn a bit too hot. Some riders on the track pulled the ABS fuse to disable the ABS; I chose to adjust my corner entry instead, and still managed to ride by some of those riders. The ZX-4RR’s quick shifter worked very well on the track, requiring only a light nudge on the shifter at full throttle to gear up or down.

The engine produces an intoxicating howl as it revs, and for a small four-cylinder, the ZX-4RR has a pretty good mid-range punch, accelerating briskly to about 11,000 rpm before power flattens out. However, it’s that sound that is at the root of the bike’s slightly neutered output.

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See, North American noise emissions are more stringent than they are in Europe; therefore, the ZX-4RR has been restricted here to reduce sound. While the engine revs to a stratospheric 16,000 rpm, it does not do so freely; the ECU is programmed to back off the throttle past 11,500 rpm, which reduces power up top. This reduction in output isn’t a problem on the road, something I had determined after sampling a ZX-4R on the road, where the engine spins mostly within the fattest part of its torque curve.

There is a solution if you do intend on taking the bike to the track, though: you can get the ECU reprogrammed by a third party to enable unrestricted power, for about US$350. According to Chuck Graves of Graves Motorsports, a U.S. firm specialising in preparing motorcycles for competition, re-programming the ECU raises output significantly, or to about the same level as the Euro-spec bike. Kawasaki does not publish horsepower numbers in North America, but European models claim a very respectable 77 horsepower and 28.8 lb-ft of torque. Adding an aftermarket intake and exhaust system can see further gains, up to 37 per cent more power than the stock bike, or up to 80 hp at the rear wheel, according to Graves.

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There are several benefits to riding a 400-cc motorcycle on the street and on the track. Most provinces have lower insurance and licensing fees for sub-400-cc bikes, making them appealing choices for street riders. On the race track, a small-displacement bike doesn’t tax you nearly as much physically or mentally as a bigger one. I was ready to go for another couple of rounds even after the last of seven 30-minute sessions; an open-class supersport would have had me as limp as a wet rag after half that time.

It’s also much easier on tires. Usually, tires are replaced at least once during daylong track tests, but the tires on the ZX-4RR looked like they could have easily taken on another day. And finally, riding a bike that doesn’t explode out of corners like a 1000-cc bike allows a rider to develop riding techniques and refine racing lines — maintaining momentum and a proper race line are paramount when you don’t have 200-plus horsepower compensating for slight track miscues.

Compromises had to be made to bring the ZX-4R and 4RR to Canada in order to meet our stringent noise standards. But this in no way diminishes the fun that can be had on the road on Kawasaki’s first-ever 400-cc inline-four to be offered here. And if you’re looking for an affordable track-day special, you have to look no further.