On February 1, 2023, Kawasaki officially launched the all-new Ninja ZX-4RR KRT Edition in the U.S. Is it an answer to the enthusiasts here who like to moan about all the cool, smaller-displacement bikes we don’t get? Let’s dive into the specs and see.
It’s powered by a shiny new, high-revving, four-stroke, liquid-cooled, dual overhead cam, four valve, 399cc, inline four-cylinder engine. Bore and stroke are 57.0 by 39.1 millimeters. Kawasaki’s peak torque figure for this little powerplant is 26.5 pound-feet at 11,000 rpm. Redline, by the way, is over 15,000 rpm. The compression ratio is 12.6 to one. This mill is mated to a six-speed gearbox with an assist and slipper clutch fitted as standard equipment.
Kawasaki says that it used die-cast aluminum cylinders and cast aluminum pistons in the creation of this engine, with a molybdenum coating on the piston skirts to increase durability. The wide bore of the cylinder allowed Team Green to use 22.1mm intake valves and 19.0mm exhaust valves to enhance airflow, and the narrow 24.8-degree valve angle was designed with combustion efficiency and engine compactness in mind.
Other trick bits inside the engine include lightweight forged camshafts and triple-rate valve springs, two-stage machining on the intake ports that’s similar to what’s found in the Ninja ZX-10R, a lightened flywheel, and 34mm electronic throttle valves to aid with Team Green’s electronics package on this bike—because yes, of course it has an electronics package.
Gallery: 2023 Kawasaki Ninja ZX-4RR
Let’s talk suspension. Up front, the ZX-4RR gets a 37mm inverted Showa Big Piston Separate Function fork with adjustable preload and top-out springs. In the rear, it gets a horizontal back-link shock with a piggyback reservoir, as well as adjustable preload, compression, and rebound damping.
The braking system consists of dual semi-floating 290 mm discs up front, paired with radially mounted monobloc four-piston calipers. In the rear, there’s a lone 220 mm petal disc with a single-piston caliper. It rolls on a pair of 17-inch star-pattern, wheels that Kawasaki characterizes as both rigid and lightweight. Those come wrapped in Dunlop GPR300 rubber. The ZX-4RR comes with both ABS and five-position adjustable brake and clutch levers as standard.
Now, what about electronic rider aids? The Ninja ZX-4RR comes with a three-mode traction control system, which Kawasaki adds “distinguishes between smooth, power front wheel lifts and sudden lift, allowing for smooth lift if acceleration is maintained.” (Obviously, for legal reasons, Team Green can’t say “do a smooth wheelie and you’ll be rewarded,” but that’s kind of how it reads.) Good news: Traction control on this bike is switchable.
The Ninja ZX-4RR also comes with a power mode that lets riders choose between full and low power, with low power representing about 80 percent of full power if you’re just getting used to the power of this bike. Four riding modes come standard: Sport, Road, Rain, and Rider (manual). The Kawasaki Quick Shifter allows for clutchless shifting—and like everything else we’ve mentioned so far, is standard on this bike.
Key dimensions of the trellis frame, including the swingarm pivot and center of gravity, were inspired by the ZX-10RR, says Kawasaki. LED headlights, turn signals, and taillight all come standard, as does the ram air duct and full-color TFT dash with two different display modes for riders to choose from. Bluetooth connectivity is available for your smartphone using Kawasaki’s Rideology the App (yes, that’s it’s full name in your app store of choice).
Curb weight comes in at 414.5 pounds, seat height is 31.5 inches, wheelbase is 54.3 inches, and the bike comes with a 12-month warranty from the factory. MSRP is just $9,699. It is, as they say, a tasty bit of kit on paper. We can’t wait to see what it’s like in real life.