One of the three major lines of
BMW motorcycles, in addition to
Airhead twins (1923-1996) and
Oilhead twins (1993-present).
They feature an odd but effective engine configuration, with the cylinders laid on their side, DOHC heads to the left and crankcase on the right. This configuration leads to a very low centre of gravity, giving K-bikes a very light feel in low-speed maneuvering.
The K stands for "Kompakt", which makes sense if you compare them to the width of BMW's existing Airhead motors at the time when the K-series was introduced.
The K series introduced several innovations that were rare or unheard-of in the motorcycle market until its introduction:
- Electronic fuel injection
- Electronic ignition
- Electronic instrument panel
The K line comprises:
- The three-cylinder, 750cc K75 series, including the K75C, K75T, K75S and K75RT;
- The four-cylinder 1000cc K100 series, including the K100, K100RT, K100RS, K100LT and (briefly) K1;
- The 4-cyl 1100cc K1100 series, including the K1100LT and K1100RS;
- The 4-cyl 1200cc K1200 series, including the K1200RS and K1200LT.
Rumours have been circulating for years that BMW is planning to replace the K series, down to two (albeit popular and well-regarded) models in recent years, with an entirely new design, possibly a four-cylinder boxer.
Nicknames:
- K-whiner: K-bikes are generally very quiet, and produce a unique whining or whistling sound.
- Flying Brick: The K engine looks a bit like a large aluminum brick.