The BMW K bikes are celebrating their 40th anniversary this year. The first bikes launched in 1983 to compete with the Honda CB750 Four, which were modern, powerful, and reliable. It has less vibrations and cost much less than the BMW Rs at that time and slowly dominating the market.
With California’s restrictions getting tougher, BMW wanted to adopt a 4 cylinder engine as well, however, if they go boxer 4, it would be seen as copying the Honda GL1000 Goldwing, and the Bavarian pride prevent them from doing so, and hence they started on prototyping with a Peugeot four-cylinder aluminum engine which was compact and the design seemed ready to use. It was mounted on the prototype longitudinally and with the cylinders horizontal, so as to have the head on the left and the crankshaft on the right. This arrangement, an absolute first, was ingenious and perfect for a BMW because it kept the low center of gravity typical of boxers but, in addition, it allowed a number of other important advantages: extraordinary mechanical accessibility, smooth rotation and the possibility of high horsepower typical of four cylinders, smaller width, and facility of coupling with the shaft final transmission.
Soon after, they embarked on producing this bike, and instead of getting a bigger engine, they continued with a compact-sized integrated system, and hence “Kompakt” and the K was born.
Long story short, the K was a shock to BMW customers as they were worried that the R series boxer engines might end. But BMW dismissed the worries and promised new versions of the R’s and the K’s would just be a different bike altogether.
The K100, K100RS, K100RT and K100LT were created over the next few years and they were made to last on the get go with durable parts and precision designs to make them be on par or better than the Hondas, and as a result, the bikes costs significantly and they sold less units than the Honda.
These bikes, although built in the 80’s, were not slow machines. With a 5 speed gearbox and 90hp, the K100RS can easily hit 220km/h. As the engine was boxy looking, they were called flying bricks as even the touring models were able to cruise above 180km/h.