What is a Slipper Clutch?

Suppose you are riding your bike at a very high speed and suddenly you need to break for some reason, maybe there’s a corner ahead or maybe just a sharp turn, you obviously have to apply breaks and slow your bike down. As now you have applied break, you need to shift down some gears at a time to avoid stalling the bike but this may risk your safety and even of your engine. The cluth would be under strain and when the engine may try to adjust the RPM causing the rear tyre to lock which may cause skidding.

Here the slipper clutch comes into work. It helps the engine to match the RPM(revolution per minute) and shifts the gear to its right position. It makes the transition of gears smoother and safer. 

So, Slipper clutch is basically a back torque limiter .What it basically does is that when you are at a high speed say in 4th gear and then there is a right hander turn,what you would usually do is brake hard shift down to 3rd and keep on pulling the clutch until the rear tyre speed and the gear speed matches meaning you have manipulated the engine breaking unless your rear tyre would lock and you would have a crash ,this is where the slipper clutch comes in ,with a motorbike equipped with a slipper clutch you need not to to wait for the rear tyre speed and the newer lower gear speed to match, the slipper clutch takes care of it for you and hence you can carry more speed.

Nowadays most mid range to high end motorcycles have a slipper clutch installed as stock.
Best example is the KTM 390duke.

KTM 390Duke has Slipper Clutch pre installed