2023 Kawasaki Ninja ZX-4RR | First Trip Assessment 

2023 Kawasaki Ninja ZX-4RR
Photographs by Kevin Wing

It’s a uncommon scenario when a motorbike debuts in a category of its personal, however that’s what we now have right here within the 2023 Kawasaki Ninja ZX-4RR. Certain, the Ninja 400 has been a preferred member of Crew Inexperienced for a number of years and is a wonderful streetbike, however its parallel-Twin engine is much extra pedestrian than the shrieking 4-cylinder motor on this little screamer that revs to 16,000 rpm. 

2023 Kawasaki Ninja ZX-4RR
The ZX-4RR is an exhilarating experience however simple to handle, making it a super alternative for aspiring sportbike riders.

Additionally necessary is how upscale this factor seems. It seems much more unique than most different smaller-displacement sportbikes, resplendent in its Kawasaki Racing Crew (KRT) coloration and graphics.

2023 Kawasaki Ninja ZX-4RR
The ZX-4RR seems extra upscale than its diminutive displacement may indicate.

Including to its upmarket presentation is TFT instrumentation, full LED lighting, an up/down quickshifter, traction management, and dual-disc entrance brakes with radial-mount monoblock calipers and customary ABS.  


The ZX-4RR has the potential to reinvigorate the sportbike market, offering a gateway to high-level efficiency in a package deal that’s each tamable and attainable. Its energy naturally pales compared to a fire-breathing ZX-10R or perhaps a ZX-6R, however the 124 mph proven on its speedometer on the finish of Thunderhill Raceway’s entrance straight demonstrates its potential for pace.  

Associated: 2024 Kawasaki Ninja ZX-6R | First Look Assessment

Class Revamp 

2023 Kawasaki Ninja ZX-4RR
For those who’ve ever wished to really feel what it’s wish to get a knee down on a racetrack, the ZX-4RR is a keen confederate.

The 400cc sportbike market raged within the Nineteen Nineties, with high-end race replicas from each Japanese OEM out there of their home markets. American importers have been skeptical that these dear little bikes would discover a lot enchantment to riders on our shores, however Yamaha took an opportunity and supplied its FZR400, which earned a popularity as one of many best-handling bikes of its period.  

Manufacturing of the FZR400 started in 1987, and the bike was frequently up to date till its demise in 1994. The Yamaha’s inline 4-cylinder used a 56.0 × 40.5mm bore and stroke mentioned to provide 59 hp at 12,000 rpm, with an over-rev functionality as much as its 14K redline. Racy steering geometry ensured agility, aided by an aluminum body that saved moist weight right down to about 410 lb. 

Sadly, I missed out on my probability to experience any of the 400s from that golden period, so I used to be stoked for the chance to check a recent model of this forgotten class.  

A New Period 

2023 Kawasaki Ninja ZX-4RR
Ergonomics are sporty however not punishing, with sufficient room for riders bigger than the creator of this story.

The Kawasaki Ninja ZX-4RR was primarily developed for Asian markets which have licensing and insurance coverage rules to encourage using smaller-displacement bikes. Simply as Yamaha took an opportunity within the U.S. market with the lovable FZR400, Kawasaki is doing the identical with this newest Ninja.  

A standard angle about small-displacement sportbikes in bigger-is-better America has been that we’re not a lot eager about them, however the U.S. market is evolving. Kawasaki tells us that uptake on the 4RR has been sturdy on the supplier stage due to the bike’s distinctive promoting proposition.  

A part of the Kawi’s distinctiveness is its means to rev as much as a stratospheric 16,000-rpm redline, which is greater than any engine supplied within the USA apart from the Ducati Panigale V4R’s 16,500-rpm rev ceiling. The 4RR makes use of a extra oversquare bore and stroke (57.0 x 39.1mm) than the FZR400 to soundly obtain these lofty revs, together with cast camshafts and triple-rate valve springs.  

2023 Kawasaki Ninja ZX-4RR
Packed contained in the fairing is a 16,000-rpm little screamer of a motor.

Kawi’s USA arm doesn’t present horsepower figures, however its Euro importer touts 76 crankshaft hp at 14,500 rpm. Torque peaks all the best way up at 13,000 rpm with 28.8 lb-ft.  

Associated: 2020 Kawasaki Ninja 650 | Highway Take a look at Assessment

EPA Killjoy 

Sadly, EPA noise rules imply that the 4RRs coming to North America are restricted, almost certainly by means of the digital throttle valves at excessive revs. Our 4RRs produce peak energy round 11,500 rpm based on a dyno chart equipped by Graves Motorsports, simply shy of 60 hp on the rear wheel. Upconverting that quantity to a rated-at-crankshaft determine interprets to about 65 hp, a minimum of 10 ponies down from its Euro spec.  

2023 Kawasaki Ninja ZX-4RR
A reflashed ECU and an aftermarket muffler can unleash 15 additional horsepower on the high finish of the rev vary.

The 4RR proved to be thrilling to experience, however I’d really feel a bit gypped to personal one and never have entry to the bike’s full potential. Bikes like these are steadily fitted with aftermarket exhaust programs that drastically enhance the sound from the tailpipe, so the EPA’s intentions will possible have restricted real-world impression.  

If I owned one, the very first thing I’d do is go to Graves Motorsports for an ECU reflash, regardless that that will be unlawful within the eyes of the EPA. For trackday/racing use solely, a reflash and a cat-back slip-on muffler from Graves ends in a claimed 76 rear-wheel hp, an enormous 37% enhance. Yee-haw!  

2023 Kawasaki Ninja ZX-4RR
The Graves Motorsports ZX-4RR prepped for racing weighs simply 348 lb and produces 80 hp on the rear wheel!

Racetrack Prepared 

Kawasaki may’ve cheaped out and hosted the 4RR’s launch with a road experience however fortunately made a bolder transfer and rented Thunderhill Raceway for us to divine the bike’s most efficiency potential. And we’re glad it did – flogging the latest Ninja on the entertaining and hilly racetrack in Northern California elicited numerous grins and 0 moments of panic.  

2023 Kawasaki Ninja ZX-4RR
The ZX-4RR was a riot to thrash across the undulating Thunderhill racetrack.

The 4RR feels gentle and manageable upon first straddle of its 31.5-inch seat. It scales in at 415 lb with its 4-gallon tank full, which equates to about 390 lb of auto weight, regardless of a metal (fairly than aluminum) body. Ergonomics are sportier than the Ninja 400 however much less punishing than Kawi’s ZX-6R or ZX-10R. The seat has a stunning quantity of fore/aft room to accommodate riders of varied sizes and altering physique positions on the observe. 

The trouble required to make use of the bike’s slip/help clutch feels impossibly gentle, and each hand levers are adjustable over 5 positions to swimsuit palms of any measurement. The 4.3-inch TFT encompasses a Circuit Mode for lap timing and to show track-related info in an easier-to-view structure. Kawasaki’s Rideology app can join the bike to smartphones.  

2023 Kawasaki Ninja ZX-4RR
Inexperienced trim across the wheel rims add to the upscale presentation of the ZX-4RR, as do the flush-mount turnsignals built-in into the fairing.

The Kawasaki Ninja ZX-4RR consists of two energy modes – with a Low setting for less-experienced riders– and three experience modes (Sport, Highway, and Rain) with preset Kawasaki TRaction Management (KTRC) and energy modes. Additionally out there is a Rider mode during which the programs might be set independently, together with three ranges of traction management with the flexibility to be switched off.  

For my first session, I used Sport mode and saved the traction management at its least-intrusive setting. The 4RR doesn’t have an IMU to tell TC or braking, relying as a substitute on wheel-speed differentials, so there’s no lean-sensitive TC or cornering ABS.  

2023 Kawasaki Ninja ZX-4RR
The ZX-4RR’s slip/help clutch and quickshifter allow clean downshifts that profit riders of all ability ranges.


It had been years since I had ridden Thunderhill, and the rider-friendly nature of the Ninja was a super confederate to relearn the observe. Pointing the bike at apexes required solely modest effort. Gear modifications have been clicked off effortlessly due to clutchless upshifts and downshifts supplied by the quickshifter, an simply seen gear-position indicator, and a tachometer that exhibits revs above 10,000 rpm on the high of the show. 

2023 Kawasaki Ninja ZX-4RR
A TFT instrument panel provides clear seems at gear place, rev counts, pace, gas consumption, and a clock. Additionally seen are the chosen experience mode, energy stage, and traction-control setting.

After just a few laps, I used to be dragging knees in corners and slicing seconds off my early lap occasions, smiling in my helmet because the Ninja complied with my inputs. The little 4-cylinder engine screams with a beautiful wail because it sings to its redline, however it’s smarter to shift round 12,000 rpm when the facility ranges off as a result of cursed EPA restrictions. Consumption snorkels with differential lengths (40mm and 60mm) do their finest to supply a broader unfold of energy, however you’ll need to rev the snot out of the little Ninja for the optimum expertise.   

Associated: Kawasaki Pronounces Extra New and Up to date 2023 Fashions

Star Energy 

2023 Kawasaki Ninja ZX-4RR
The ZX-4RR’s nostril encompasses a central ram-air consumption and a wing-like beak.

Through the subsequent session, I discovered myself behind a rider I didn’t acknowledge from the motojournalist ranks. He was slicing some good strains, and it was enjoyable to catch him in some locations and lose time in others throughout our little cat-and-mouse recreation.  

On the finish of our 30-minutes session, I walked over within the pits to say hi there to this stranger and categorical the leisure I bought from dicing with him.  

“Oh, hello, I’m Dax,” he replied.  

Wait a minute…Dax? There can’t be many Daxs on the earth, so I lastly made the connection that I used to be ripping round with Dax Shepard: actor, podcaster, and husband of film star Kristen Bell! It was pleasant to see a star with the flexibility to tear round a racetrack.  

“Being broke in Michigan, what I might’ve liked was a Corvette ZR-1. I bought my Katana 600 for $1,800 used, and it was sooner than a ZR-1,” Shepard informed us about his love for pace, which started with a humble Honda Spree.  

“I’ve at all times been blown away by how cheap it’s to have efficiency with a motorbike,” mentioned the co-host of High Gear America. “I had a few totally different observe bikes, and aside from tires, I’d by no means performed one factor to them. So the notion that you would have a car that you would go to 20-plus trackdays and never be changing rotors and pads and suspension parts, it’s bang for the buck – probably the most enjoyable anybody may have.” 

Please, Sir, Can I Have One other? 

2023 Kawasaki Ninja ZX-4RR
The ZX-4RR willingly sucked up lap after lap at Thunderhill and left the rider contemporary for repeated periods.

In contrast to a literbike, which might be exhausting to thrash round a racetrack, I remained raring to go even after full 30-minute periods. What’s refreshing is time – time to ease your grip on the bars, time to breathe, time to research.  

Though I didn’t really feel traction management intruding a lot throughout earlier periods, I did discover ABS kicking in at a few braking zones. I ended up disabling traction management and ABS so I may experience unencumbered by the digital nannies. Energy software turned extra direct with a stronger pull out of corners, so TC certainly had been kicking in throughout earlier stints.  

I used to be initially fearful in regards to the grip from the inventory Dunlop Sportmax GPR300 tires, which appeared to be a substandard alternative for a trackday. Surprisingly, they caught fairly nicely, all the best way as much as and previous footpeg-scuffing ranges.  

2023 Kawasaki Ninja ZX-4RR
Greatest-in-class braking is supplied by radial-mount 4-piston monoblock calipers biting on 290mm discs. ABS is customary gear.

The suspension carried out fairly nicely for my weight, though heavier riders have been making changes to the inverted Showa fork and totally adjustable Showa BFRC Lite shock that’s much like the one used on the ZX-10R. The 37mm fork makes use of SFF-BP internals, during which the large-diameter damping piston gives extra floor space to work together with oil, which permits the fork to maneuver extra easily in the course of the preliminary a part of its stroke. Adjustable spring preload on a fork is a primary for this class, however it’s the one setting that may be altered.  

2023 Kawasaki Ninja ZX-4RR
The seat cowl fitted to our check bike is obtainable for $230.95 from Kawasaki.

The radially mounted 4-piston monoblock calipers and 290mm discs are a lot for bleeding pace from the 399cc engine and provide a good quantity of suggestions. Switching off ABS supplied a giant enchancment in confidence on the racetrack. The quickshifter was an enormous profit as nicely, with auto-blipping downshifts and the slipper clutch permitting hurried gear modifications. 

Who Desires One? 

Being in a category of 1, the 4-cylinder ZX-4RR stands other than different small-displacement choices. Its $9,699 MSRP allows the bike to have high-end options, however some will level out that a way more highly effective ZX-6R prices solely $2,600 extra when geared up with ABS.  

2023 Kawasaki Ninja ZX-4RR
A totally adjustable shock is uncommon for this displacement class. A helmet lock (seen behind the passenger footpeg bracket) is a comfort merchandise that has turn into uncommon on trendy bikes.

Or you would get the twin-cylinder Ninja 400 for as little as $5,699 with ABS, however you then’d miss out on TFT devices, dual-disc entrance brakes, traction management, and adjustable suspension, plus you’d quit a bunch of energy and the siren tune of a high-revving four-cylinder motor.  

It’s value reiterating how a lot of a gigglefest it’s to hammer a modestly powered however light-weight sportbike round a racetrack, even for riders with a long time of expertise on high-powered literbikes. And for many who could be taking to the observe for the primary time, a sporting bike just like the ZX-4RR is a perfect instrument to learn to do it correctly.  Mr. Graves, please ship a reflashed ECU ASAP. 

2023 Kawasaki Ninja ZX-4RR

2023 Kawasaki Ninja ZX-4RR Specs

  • Base Worth: $9,699 
  • Guarantee: 1 yr., unltd. miles  
  • Web site: Kawasaki.com 
  • Engine Kind: Liquid-cooled, transverse inline-4, DOHC w/ 4 valves per cyl.  
  • Displacement: 399cc  
  • Bore x Stroke: 57.0 x 39.1mm 
  • Horsepower: N/A 
  • Torque: N/A 
  • Transmission: 6-speed, cable-actuated slip/help moist clutch, up/down quickshifter 
  • Ultimate Drive: Chain  
  • Wheelbase: 54.3 in.  
  • Rake/Path: 23.5 levels/3.8 in. 
  • Seat Peak: 31.5 in. 
  • Moist Weight: 415 lb  
  • Gas capability: 4.0 gal.

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