Rennie Scaysbrook | July 29, 2023
The junior four-cylinder, the Kawasaki Ninja ZX-4RR, is back in the hands of the company that made it famous.
Photography by Ryan Nitzen, Kevin Wing
You guys in America missed out because the 1990s were a golden era for little sports bikes:
Honda’s CBR250RR and CBR400, Yamaha’s FZR250 and 400, Suzuki’s GSX250 and GSX-R400, and of course, the Kawasaki ZXR400.
In my home ground of Australia, these things were ripping roads and ear drums apart in the ’90s, riders bouncing the little four-pots towards, in some cases, near 20,000 rpm redlines. As a sport bike-mad teen, all I wanted was a Honda CBR250RR (junior riders were limited to 250cc or less while they were classified as learners). I got a Yamaha SRV250 café racer, which wasn’t love at first sight but grew into love over time.

That was over 25 years ago, more than half my lifetime, but I can still remember those little screamers and lament that they have all but disappeared from the world’s roads.
But they haven’t disappeared entirely.
Kawasaki made noise a couple of years ago that they intended to build a 21st-century four-cylinder 400, and, what’s more, Kawasaki USA intended to homologate it and bring it to America. Typically, we are the last to get pretty much every cool model from the major manufacturers, but this time, we’ve jumped the queue to the front, and here it is. A bike teenage me would have done very questionable things to have it in my garage.
The 2023 Kawasaki ZX-4RR is a complete anomaly in modern sport biking. It’s especially confusing because Kawasaki has a firm hold on the junior sport bike market with their Ninja 400, which has sold more than enough across the globe to sink a couple of the container ships on which they left Japan.
The 4RR is all-new, but you could be forgiven for thinking the spec sheet reads something like the larger ZX-636. Items like ram air, fully adjustable suspension, four-piston monobloc brakes, quickshifter, and a screaming 16,000 rpm redline is normally reserved for race-spec 600s, but all of it can be found on the 4RR for under $10K at $9699 for this KRT Edition (there’s an extra base model for other markets that’s not coming to America).

The 4RR feels like it’s a Ninja 400 that’s spent too much time eating burgers and not enough time running, a bit like the guy writing this article. The chassis is a Ninja 400-style steel trellis number that runs the Horizontal Back-link and BFRC-lite shock directly off the swingarm, so you get an exceptional feel from the back end despite the settings being on the soft side straight out of the box.
The ride position is