check out the silver cover

Kawasaki is experimenting with changing the flywheel or flywheel weights on Eric Bostrom's Superbike, judging from the quick-change case cover that Kawasaki has built for the machine. Easily seen in this photo, the obviously hastily-built cover is made from aluminum.

Why this is done: swapping flywheels, position or the flywheel weights themselves is a modification made when one wants smoother power on a low traction racetrack. The power hit is softer, traction increases, but steering with the rear tire, or assisted by breaking the rear tire loose, goes away.

Normally on an in-line four-cylinder, one has to swap crankshafts to modify the weight of the flywheel. With this handy cover, it is done quite easily and quickly on the Kawasaki.