The history of Japan’s pocket rockets

We’re all extremely old around here, so we most certainly remember the last time Kawasaki had a 399cc inline-four mini-superbike on its books. That was around 1999, when the last of the ZXR400s were drifting off the showrooms of the kingdom, overshadowed by the 21st century hot-poop machinery that was just around the corner.

Bikes like Yamaha’s R6 and Kawasaki’s own ZX-6R B1 were bringing 400cc handling with near-750cc power, and didn’t cost much more than the high-tech 400s of the 1990s. That makes sense when you think of it: the size of the holes inside an engine doesn’t really affect how expensive it is to make, and the jewel-like mini-superbikes were every bit as trick as their bigger brethren.

The 400cc class only existed because of a quirk of Japanese rider licensing laws: getting a licence to ride a 250cc twostroke or 400cc four-stroke was much easier than a ‘full’ licence, so many home market riders didn’t bother with anything larger. The white-hot competition between the big four Japanese firms at the time produced some incredible machines: Honda’s VFR and RVF400 V-fours PLUS a CBR400RR inline four and an NSR250R stroker; Yamaha’s FZR400 RR SP EXUP and TZR250; Suzuki’s GSX-R400 and RGV250 models.

Kawasaki had the KR-1S parallel twin two-stroke that could make 60bhp for a few hours before its piston-ring pegs fell out, but it also had the much more reliable ZXR400. That had a design that aped Kawasaki’s ZXR750 superbike, including the awesome ‘Hoover hose’ cooling air intake pipes above the tank.

The ZXR400 was officially imported into the UK for eight years, from 1991-99, and sold well despite its stiff price. It cost around £5k in 1999, just £500 less than the ZX-6R and £1,450 less than a full-on ZX-7R – so you had to be really keen to opt for one. The old bike was a good bit lighter than the new ZX-4R, weighing in at just 164kg dry or 177kg wet. It made much less power though: just 65bhp as standard, 15bhp down on the new machine.