Magneto rotor with a one-way clutch for Viper 125-200 cc motorcycles and similar (China, Minsk). The rotor turns together with the crankshaft, creating the magnetic field for the generator and ignition. The one-way clutch transfers rotation from the starter to the crankshaft and disengages it after the engine starts.
Signs of a fault: the starter spins freely, you hear cracking when starting, charging has stopped or the magnets have lost their magnetism. A puller is needed to remove the rotor.
