Perhaps more than any other decade before or since, the '80s was a hotbed of motorcycle evolution. Starting with motorcycles like Yamaha LCs and Honda VFs, this was a period of experimentation and rapid development that concluded with clearly deranged motorcycles.
Frame design went through every conceivable form, from steel backbones and cradles to aluminum perimeters, with wheel size varying in both width and diameter. But by 1986, Yamaha with the FZR400, Suzuki with the GSX-R400, and Honda with the NSR250 plus VFR750 had all realized the best way for handling was a stiff frame, and that the best way to making it stiff was by joining the steering and swingarm pivot with the shortest path and with plenty of material edge-on.
Beam frames like the first Deltabox on the Yamaha YZR were the result, the motorcycle also having a 1400mm wheelbase and 24” steering angle – identical to the latest Kawasaki ZX-6R. The Yamaha also set the default engine layout; a compact, liquid-cooled, inline four with 16-valves, tilted forward for improved weight distribution and direct inlets. The format clearly worked, with the Yamaha FZR1000 and Honda CBR400RR using similar specifications for 1987. In the main, wheel size settled on a 17 inch front and 18 inch rear, until the CBR250R, TZR250, RGV250, CBR750 and GSX-R750 all adopted 17-inch rims for both ends in 1988.
And so, by 1989, the decade ended in a flourish with Yamaha's FZR750R, FZR1000 and the Kawasaki ZXR750. The foundations had been laid for the modern sportsbike as we know it now.