While purists and historians will correctly point out that Italy’s MV Agusta released the first production inline four with a disc brake (1966's 600-4) the attention, adulation and technological significance of the Honda Four cannot be denied. Giving credit where credit is due, it is possible the abundance of press and coverage generated by the release of this motorcycle may actually fall short in light of its impact on the industry. As the two-wheeled symbol that ushered in the modern era, there remain two basic and unchanging dividers on motorcycling’s historical time line; pre and post World War II production, and the Honda’s CB 750 of 1969.

Importing on a world-wide basis by 1970, all of the remaining members of Japan’s big four responded in varying degree to the big Honda. Kawasaki’s profound 900 Z1 was first, upping the ante with dual overhead cams and a clear edge on performance. Suzuki and Yamaha held out longer, releasing a variety of two-stroke models in two and three cylinder configurations, with Yamaha adding to the mix with its version of the four-stroke parallel twin. By 1977, all were campaigning an across the frame four-stroke multi; Yamaha with its shaft-drive XS 750 triple and Suzuki’s brilliant, twin-cam GS 750. Surrounded by gun boats, Honda’s evergreen 750 was showing some brown around the edges, and as the factory was busy developing the new and exciting designs (including liquid cooled V-fours) that would eventually join the GL1000 flat four and six-cylinder CBX, the trademark Four went under the knife for more horsepower.

Like Suzuki’s decision to refocus its GT 750 triple when the RE5 rotary was introduced, 1975's GL1000 tourer lifted flagship duties from the 750 Four, allowing Honda’s engineers to sharpen it more into a pure performance sportbike. Due to customer demand the four-pipe K-model was retained, joined by the Super Sport 750F. With revisions to the exhaust, compression, cam timing and sporty monocoque-like bodywork, the F was an instant hit in both the 750 class and the smaller, but no less striking CB400F. Two years before releasing its own DOHC four in 1979 and needing more competitive power, Honda put the SOHC back on the bench one last time.

http://motorcycling.speedtv.com/article/vintage-bike-of-the-month-1978-honda-cb750f3/