[Ghostt]

Clutch springs determine the recoil of the clutch lever; how hard it is to pull the lever and, when the lever is released, how much force is holding the lever up against its stop. Weak clutch springs make it very easy to pull the lever, which is convenient for weak riders, but can result in some clutch slippage, as the engine is not fully engaged when the clutch is released. With stiffer clutch springs, the lever is harder to pull, but when the lever is released, the clutch is fully disengaged, and there will be no clutch slippage, so the engine is allowed to direct all of its power to the rear wheel. It is believed that, since many newbies and female riders are attracted to the Ninjette & EX-500, Kawasaki opted to use softer clutch spring that would allow easier disengagement of the engine.

Also the KZ1000 uses more plates and steels, almost 2x as the Ninjette.

But given the power output of the Ninjette, the plates and steels are still a decent amount, if you change out the springs themselves. This is assuming you don't abuse the clutch itself, keep it adjusted properly, and of course use the right oil.