Which rotor ?

Chaps,

I have the high output 3 phase stator fitted to my 1974 850 (not becasue I really need a higher total output, but becasue it delivers a higher low rpm output).

My rotor is loose and need replacing. Is there a particular rotor that suits this application best?

Nigel, usually i'd say RM20 Rotor Lucas Part Number LU54202299

However, if you are finding that it's to loose on your crankshaft, maybe consider the Sparx.

Their stators are crap quality, and i cannot recommend them at all, but i can't see where you could go wrong with one of their rotors.
I had to ream the Sparx rotor for a bike we did in order to get it onto the crankshaft.
They are proud of the fact that it's an interference fit onto the crankshaft.

This may give you what you're looking for.

Thanks for that.

When I said loose, I meant the rotor itself is starting to show signs of coming apart. Fit on the crankshaft is good.

I’ll stick with the Lucas. Thanks for the part number.

i have also had a sparks rotor start to loose a magnet and rub the stator. more junk from sparks.