BMW K 100
BMW’s first four-cylinder motorcycle hid its biggest surprise in plain sight: the engine lay on its side.
BMW K100 PL.JPG · Beemwej · CC BY-SA 3.0
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More than a set of wheels.
In 1983 BMW added a new engine family alongside its long-established boxers. The base K 100 exposed its machinery, while other K models wore fairings for different jobs. The new layout was a major change in BMW motorcycle engineering, but it retained shaft drive and an integrated approach to the powertrain.
Look a little closer.
The unfaired K 100 and the faired K 100 RS are different models, even though they share the same basic four-cylinder idea.
Photos show an example of the model or generation. The pictured vehicle’s year, equipment, or modifications can differ from the specification described here.
A four-cylinder engine that lies down
An inline four normally makes people imagine a tall row across a motorcycle. BMW arranged this one along the bike and turned it on its side. The resulting low engine position helped lower the centre of gravity. The unfamiliar appearance therefore followed a practical handling decision, rather than a styling trick.
Source: BMW Classic · The BMW K 100 from 1983 ↗The drivetrain becomes one connected assembly
BMW grouped the engine, directly attached gearbox and single-sided rear arm with its driveshaft into what it called the Compact Drive System. Thinking about these parts together simplified the motorcycle’s underlying layout. The base K 100 left the assembly visible; fairings and touring equipment defined other branches of the K family.
Source: BMW Group Classic · BMW K 100 ↗Where these facts come from
- BMW Group Classic · BMW K 100
- BMW Classic · The BMW K 100 from 1983
- BMW PressClub · 80 years of BMW Motorcycles
Selected facts checked for this edition. Some source pages link to broader model families. Last reviewed 2026-10-02.