The all-new Kawasaki Ninja ZX4RR 2023+ Product List Edition is a growing list of Spears Racing parts.The Kawasaki ZX4rr 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.According to Kawasaki Motors, the ZX-4R and ZX-4RR bringing high-revving four-cylinder fun to trackdays across the country.
The liquid-cooled DOHC engine comes with six-speed gearbox and assist/slipper clutch, and in ZX-4RR trim, a quickshifter is standard. Cylinder capacity is 399cc from an oversquare 57 x 39.16 mm bore/stroke.
While those trick 400s of old brought stout aluminum perimeter frames to the public (they’d previously only been used in Grand Prix racing), the new ZX-4RR uses a cost-effective steel-trellis frame and a steel banana-style swingarm. Looking at the spec chart, we see that the wheelbase measures 54.3 inches, which happens to be identical to the Asian-market Kawasaki ZX-25R, that this 4RR is largely based on. Front-end geometry has 23.5-degrees of rake and 3.8 inches of trail, which are actually a bit more aggressive than the 250′s and in fact quite similar to the quick-steering 400s of old. Claimed wet weight is 415 pounds

Engine 399cc, liquid-cooled, 4-stroke, DOHC 16-valve in-line four
Bore x Stroke 57.0 x 39.1 mm
Compression Ratio 12.3:1
Fuel System Fuel injection: ø34 mm x 4
Ignition Digital
Starting Electric
Lubrication Forced lubrication, wet sump
Transmission 6-speed, return
Clutch Wet mult

Frame Trellis, high-tensile steel
Front Suspension / Wheel Travel ø37 mm inverted fork (SFF-BP) with top-out springs / 120 mm (4.7 in)
Rear Suspension / Wheel Travel Horizontal Back-link, gas-charged shock with spring preload adjustability / 112 mm (4.4 in)
Rake / Trail 23.5° / 97 mm
Steering Angle (L/R) 35° / 35°
Front Tire 120/70ZR17M/C (58W)
Rear Tire 160/60ZR17M/C (69W)
Front Brakes Dual semi-floating ø290 mm discs with radial-mount, monobloc, opposed 4-piston calipers
Rear Brake ø220 mm disc with single-piston caliper

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