The great advance in horsepower is possible because today’s engines are strong enough to remain reliable at higher rpm.

Rob Muzzy's Kawasaki Superbike of the early 1980s made something like 152 horsepower at 10,250 rpm. The current factory Kawasaki Superbike raced in the world championship by Jonathan Rea and Tom Sykes is based on the ZX-10R and makes more like 220 horsepower at 14,750 rpm.

That classic Z-based engine was a real transitional design. It had an all ball-and-roller crankshaft pressed together out of pieces. And that pressed-together crankshaft set a limit, so things started to go bad in a hurry at 11,000 rpm.

But the ZX-10R has a forged steel crankshaft made in one piece with durable multi-layer bearings. It has split and bolted connecting rods. And it has a reliable oil system designed so that the oil pump does not get air—the enemy of plain bearings at high rpm.

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