I follow all that, they have a different firing order etc., but they still fire one cylinder per 180 degrees (four cyl four stroke) of crankshaft revolution, just like an inline four, but they sound distinctly different. I cant figure out why, and I haven't heard a satisfactory explanation. For instance, if you changed the camshafts on an inline four to give a different firing order the car (or bike) would sound the same. In fact I believe early Kawasakis had different firing order (1,4,2,3) from Honda (1,4,3,2) but sounded pretty much the same. If it's doing 1000 rpm then it's firing 1000 times a minute at 1/1000 minute intervals regardless of its firing order or configuration. So why does it sound different?