Well, as I'm sure ya know Ron, one of the primary reasons the V-twin engine became so popular in motorcycles was because early motorcycles were basically just bicycles with engines placed inside their frames. And the way bicycle frames are designed with the down-tube going down to the pedal crank and meeting there with the seat post tube creating a "V" shape, made a V-twin shape engine a natural to fit into that space if more than a single-cylinder motorcycle was desired.
