BMW R-5 494cc OHV Flat Twin

In 1936 BMW introduced a completely new model with considerably more power than its predecessors, achieved by employing two chaindriven camshafts allowing for much shorter pushrods to the overhead valves, with a significant increase in maximum RPM as a result.

The engine was also used after the war, with minor changes, in the R-51/2.

Horizontally Opposed Twin

Examples include BMW, Zundapp and Douglas HO Twins have conrods running on a common crank, with one on the exhaust stroke and the other on inlet.

Shaft Drive

Examples include BMW, Zundapp and Velocette LE Cardan drive eliminates chain and associated mess and maintenance. Often referred to as a "diff", the final drive unit consists of bevel crown and pinion gears.