Harley-Davidson have a patent on the sound of the motor

Harley Davidson attempted to patent their engine sound in the US. Their competitors argued that many engines use that same mechanical configuration, that their isn’t anything unique about that, and as a result many engines make similar sounds.

Harley withdrew their patent application in 2000, without any ruling being made.

So, no, Harley Davidson does not have a patent on the sound their motorcycles make. They do have many patents on the construction of their engines.

(Video as a visual example of the sound of the engine)