1973 BMW 900cc R90/6, R90S Motorcycle Batteries
In 1973 BMW introduced two new models of bikes with 898cc engines, the R90S and the R90/6. For such large bikes the R90S and R90/6 were not the fastest bikes of that size, but they were the most comfortable. Even though on the outside it looks like the only significant difference between the R90S and /6 is a fairing, there is more than meets the eye here. The R90S was given a higher compression ratio than the “naked” /6; 9.5:1 instead of 9:1 and 38mm Dell’Orto carburetors with accelerator pumps as well. It also added 7hp on the naked version. Other changes, such as larger fuel tank, second disc on the front brakes and a steering damper, gave the S a definite edge over the /6 in performance. The R90/6 for its part was given a slightly smoother suspension, as it was touted as the touring bike, and even though the R90S was the “Sport” version, the /6 still maintained a significant presence as a sporting machine.