Q Parallel-twins are usually made with 180-degree cranks. I suppose this allows the engine to be smoother as inertial forces are in balance. The firing order works out to 540 and 180 degrees, though, so that must mean some strain on the transmission and chain plus a rocking vibration from the offset of the two cylinders. Originally, most twins used 360-degree cranks, providing an even firing order every rotation. Lately, Triumph has gone with 270-degree cranks, which gives a firing order of 270/450 degrees, striking a compromise between rocking couple and inertial forces. A twin with a 180-degree crank gives the engine an off-kilter rhythm, but apparently it's not all that pleasant to listen to. I wonder why no one has tried using a 315-degree crank on a parallel-twin, giving a firing interval of 315/405 degrees, just like a Harley? You would get that great sound and the firing order would be semi-evenly spaced for less strain on the drive train.