What gives Harley Davidson Motorcycles that legendary sound?
The design of the classic Harley-Davidson two cylinder V-Twin, with the pistons mounted in a 45° “V” angle position on a single pin crankshaft. Both pistons are connected to the pin through their connecting rods and cause the uneven firing of the pistons. Early V-Twins used a dual firing system; both spark plugs fired no matter which cylinder was in its compression stroke, then the other firing in the exhaust stroke. The 45° cylinder angle design of the V-Twin creates a firing order that is, first cylinder fires, then the second cylinder fires 315° later, then a gap of 405° until the first cylinder fires again. This causes the distinctive Harley sound. The 45° cylinder “V” angle was a rudimentary design choice in order to engineer a larger, high torque engine in a small space. The initial design continues this day and the sound remains a Harley-Davidson brand. Harley-Davidson Motor Company filed an application for a sound trademark in February, 1994 for the distinct sound their engine
