| Diagram | Fig. 1 — CRANKSHAFT, PISTON AND TIMING GEARS · ref 37 |
| Subsystem | engine bottom |
| Listed in parts books | 1963–1968, 1970–1974 |
Rotor, type RM 19
Lucas RM19 alternator rotor, the magnet rotor that spins with the crankshaft to generate charging current.
This is the RM19 rotor from the Lucas alternator setup, the permanent-magnet piece that spins on the crankshaft and generates the AC current your charging system runs on. It shows up across a long run of catalog entries touching the crankshaft, timing cover, and chaincase/alternator figures, so it's a mainstay of the alternator-equipped charging system rather than a one-off part.
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The rotor works as a pair with the stator (the fixed windings it spins inside of, bolted to the timing cover area). If you're troubleshooting a weak-charging or no-charging bike, the rotor is one half of that story - check it alongside the stator and the rest of the charging circuit rather than assuming one part on its own.
Our records show this part number was later superseded by 54202299. If your parts book or an old invoice lists 54213901, that's the same physical rotor under its earlier factory number - useful to know when cross-referencing with a later catalog or another supplier's listing.
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