The all-new 2023 Kawasaki Ninja ZX-4RR KRT Edition upends the small-displacement road-racing class with advanced technology and a four-cylinder motor—something we haven’t seen in a sub-500cc supersport bike in decades. Priced at $9699—nearly double the tariff for the twin-cylinder Ninja 400—this motorcycle is aimed at serious riders looking for high performance. It’s an all-new motorcycle, so we’re starting from scratch here.
- The four-cylinder motor for the 2023 Kawasaki Ninja ZX-4RR KRT Edition is liquid-cooled and sports double overhead cams. Kawasaki went all in with this short-stroke design. With 57mm aluminum pistons, the stroke is a mere 39.16mm long—just over an inch-and-a-half—with each cylinder displacing a tad less than 100cc.
- Kawasaki tells us that ZX-4RR’s rev limiter kicks in at over 15,000 rpm. With such a high ceiling for the engine speed, the torque peak doesn’t happen until 26.5 ft-lbs are produced at 11,000 rpm. As has been the case for years with the Japanese manufacturers, no maximum horsepower figure is quoted.
- Electronics allow personalizing two aspects of the power delivery. There are three preset riding modes—Sport, Road, and Rain—plus a customizable Rider mode. This gives the pilot three levels of traction control (plus off) and two power modes, Full and Low, to combine to taste. The power mode reduces maximum output and slows the throttle response.
- A 4.3-inch TFT display provides access to a wide range of information. In addition to the info you would expect, a Circuit mode for track days accentuates the info you need for that application. The lap time is prominently displayed, making it readable while putting in maximum effort. When the rev count gets into five figures, the gear position indicator and tachometer display are enhanced for easier monitoring. With the dash paired to your smartphone and using Kawasaki’s Rideology app, you have access to a wide variety of features, including maintenance needs, email and call alerts, dash display tuning, and GPS-based navigation.
- Power production on the 2023 Kawasaki Ninja ZX-4RR stars with a Ram Air intake system. An intake duct above and between the headlight results in a pressurized airbox for additional power, particularly at higher speeds. From there, the air is directed to the four ride-by-wire 34mm throttle bodies via downdraft intake funnels measuring 60mm and 40mm.
- The interiors of the intake ports are fine-sand cast for smooth airflow. The intake ports are a two-stage design to enhance straight-line intake.
- The four cylinders each get a pair of 22.1mm intake valves and 19mm exhaust valves. The valves are positioned at a narrow-angle in improve combustion and keep the motor compact. Kawasaki used triple-rate valve springs to fine-tune operation.
- The aluminum pistons have a crown that facilitates a 12.6:1 compression ratio. The pistons have molybdenum-coated skirts for smoother operation and enhanced reliability, and sit inside a die-cast aluminum cylinder.
- The crankshaft is lightweight to improve throttle response. The connecting rods are carburized to keep them light and durable, while the ratio is optimized to reduce vibration and mechanical loss.
- The engine is cooled by a 30-row radiator. It cools the air after it flows around a design that increases cooling, especially in the spark plug area, to reduce the knocking due to heat. The fairing helps dissipate heat from the engine, and ducts direct heated air from the radiator away from the rider.
- To reduce emissions and sound, the headers get joint pipes. The collector under the engine houses triple catalyzers. That allows for easy installation of a slip-on muffler, though Kawasaki claims a “clear, racy exhaust note” from the long stock muffler.
- The 2023 Kawasaki Ninja ZX-4RR has a six-speed transmission with a quickshifter standard. The clutch is of the assist-and-slipper variety. The up/down quickshifter works when the motor is spinning at 2500 rpm or higher.
- World Superbike experience informs the chassis geometry. Both the trellis frame and arched swingarm are high-tensile steel, resulting in a curb weight of 416 pounds with the four-gallon fuel tank filled. The rake is an aggressive 23.5 degrees, and the 17-inch wheels are shod with Dunlop Sportmax GPR-300 rubber. Showa supplies the suspension—an SFF-BP inverted fork with adjustable spring preload, and a cantilevered fully adjustable BFRC Lite piggyback-reservoir shock with linkage assistance.
- Triple-disc braking slows down the 2023 Kawasaki Ninja ZX-4RR. There is a pair of 290mm semi-floating discs on the five-spoke front wheel, each grasped by a radially mounted four-piston monobloc caliper with Kawasaki branding. The 220mm rear disc gets a single-piston Nissin caliper. Nissan also provides the ABS control unit.
- The ZX-4RR’s riding triangle is more aggressive than a Ninja 400, though not as race-focused as a Ninja ZX-6R. The clip-ons mount just below the top triple-clamp. The tank is narrow at the knees for easier gripping, and the 31.5-inch high seat is designed to make it easier for the rider to move around on the motorcycle. A firmer seat from Kawasaki Genuine Accessories is available for track riders, and a pillion seat cover is also in the catalog. The footpegs are derived from supersports, while the hand levers are five-position adjustable.
- Lighting is all-LED. The front turn signals are integrated into the fairing, while the taillight has a ZX-10R feel.
- At $9699, the 2023 Kawasaki Ninja ZX-4RR KRT Edition is not an inexpensive motorcycle. It slots between a pair of higher-displacement twins—the Yamaha YZF-R7 ($9199) and Aprilia RS 660 ($11,499). Sporting the KRT graphics, this is a sophisticated small displacement motorcycle built with track days in mind. It’s due to arrive at Kawasaki dealers in the Spring, and we look forward to riding it ASAP.
2023 Kawasaki ZX-4RR KRT Edition Specs
ENGINE
- Type: Inline-4
- Displacement: 399cc
- Bore x stroke: 57.0 x 39.2mm
- Maximum torque: 26.5 ft-lbs @ 11,000 rpm
- Redline: 15,000+ rpm
- Compression ratio: 12.6:1
- Valvetrain: DOHC; 4 vpc
- Fueling: EFI w/ four 34mm throttle bodies
- Cooling: Liquid
- Transmission: 6-speed w/ quickshifter and Positive Neutral Finder
- Clutch: Web multiplate w/ assist and slipper functions
- Final drive: Sealed chain
CHASSIS
- Frame: Steel trellis w/ steel swingarm
- Front suspension; travel: Spring-preload adjustable Showa SFF-BP 37mm inverted fork; 4.7 inches
- Rear suspension: Linkage-assisted, fully adjustable, cantilevered Showa BFRC Lite piggyback-reservoir shock; 4.9 inches
- Tires: Dunlop Sportmax GPR-300
- Front tire: 120/70 x 17
- Rear tire: 160/60 x 17
- Front brake: 290mm semi-floating petal disc w/ radially mounted 4-piston monobloc calipers
- Rear brake: 290mm petal disc w/ single-piston caliper
DIMENSIONS and CAPACITIES
- Wheelbase: 54.3 inches
- Rake: 23.5 degrees
- Trail: 3.8 inches
- Seat height: 31.5 inches
- Fuel tank capacity: 4.0 gallons
- Curb weight: 416 pounds
- Color: Lime Green/Ebony
2023 Kawasaki ZX-4RR KRT Edition Price: $9699
2023 Kawasaki ZX-4RR KRT Edition Phoot Gallery
