The RM rotor upgrade for Yamaha Motorcycles is a well-priced alternative to OEM parts. Anyone who rides or repairs a Yamaha YZF R1, FZ1 or FZ8 is probably aware that the standard flywheel is prone to failure. The result of the magnets coming loose is they are smashed to pieces against the rotor, causing catastrophic failure and resulting in an expensive engine strip down to remove all the magnetic fragments of metal from the engine internals.
Serious consideration should be given to replacing OEM rotors before they fail as a new rotor is considerably cheaper than repairing a damaged engine.
Shop with confidence, precision balanced part, with magnets that are fully enclosed so there is no danger of them breaking apart. Install and forget. Replaces OEM p/ns: 5VY-81450-00-00, 2SH-81450-00-00.