Genuine Lucas RM20 Rotor, 6 Pole with welded 0.752" centre.
This rotor supercedes all other specifications.
As fitted to most British motorcycles (late 50's to 70's) equipped with alternators.
Magnetic centre of the Alternator. Normally fits onto the crankshaft. This part can quite often be the simple solution to a low alternator output.
Shaft diameter: 19mm
Outside diameter: 74mm