To look at what a slipper clutch is let’s start with engine braking and what happens without a slipper clutch. When you roll off the gas the bike slows down. Friction from the moving parts, like the chain and wheel bearings, has a drag affect, but the slowing engine also provides a braking force to the rear wheel through the crank/sprocket/chain.
2Wheel Tuner Magazine – October 2007