- By cannonball
You’ve probably noticed that on the majority of late-model sportbikes the projecting round cover for the clutch is located surprisingly high on the right side of the engine. This is because the two gearbox shafts—the input shaft carrying the clutch and the output shaft carrying the drive sprocket—are “vertically stacked” one above the other rather than one ahead of the other as they used to be.
When I was a very young man and first took apart a Japanese-made motorcycle engine, I was impressed by its rationality and ease of assembly. Once the lower half of its horizontally split crankcase was removed, all parts were in plain view—crankshaft at the front, then the gearbox input shaft, the output shaft, and behind them, the kickstart shaft—neatly sandwiched between the two crankcase halves. This simple layout, I would soon find, also allowed easy transmission setup (how deeply the various dog sets engaged each other).