The cam chain tensioner pushes on the slipper to keep the chain driving the camshaft tight at all times. When worn or sticking it lets the chain slap: rattling at idle, fast slipper wear and, at worst, a jumped tooth that lets valves and piston touch.
Here you will find cam chain tensioners, slippers and guides for KTM 4-stroke: SX-F 250, SX-F 350, SX-F 450, XC-F 250…