- Sun Dec 20, 2020 3:50 pm
#94530
It might help not to get too Bullet-centric over this one, Lucas produced a number of different alternators all with the same stator mounting stud spacing but differing widths and outputs, both for 6 and later 12V, as well as their earlier stuff with the smaller diameter rotors.
The classic 12V single phase alternator for so many British bikes is the RM21, originally claimed to be good for 120W and to answer Davedup's original question, if it is intended as a 12V alternator then the stator will only have TWO wires, and the familiar green gunk encapsulating the windings/coils. The otherwise very similar RM19 will have THREE wires for 6V use, but these can also be wired up to produce 12V for a suitable system.
Then we get onto the Lucas high-output single-phase alternators (RM23?) @ 180W and the THREE PHASE alternators which came in 110 and 180W flavours, I believe that these all use fatter rotors and stators but are still physically interchangeable with the RM21/19. Three-phase Lucas alternators also have three wires, as well as 9 sets of windings instead of 6.
NOW we came to the Indian Bullet alternators (pre Electra-X and EFI) which are irrelevant as far as the Redditch twins are concerned, though you could fit one as an economy measure! These started off as copies of the older 3 wire Lucas (same dimensions) and were used on 6V and 12V Bullet systems, with the 4 wire alternators and AC headlights appearing in the late 90's. Lucas DID produce their own 4 wire stators with the green encapsulation, but as far as I know these were produced exclusively for our hosts as an upgrade for the Indian Bullets and were never marketed for anything else. It's possible that the E/S and Sixty-5 Bullets had beefier alternators for the extra demands on the electrics, maybe someone could confirm or deny this? There are also SIX wire Indian alternators which are still based on the Lucas design, though these are modified to provide CDI ignition on some home-market 350s.
As for whatever Davedup has been sold - I suspect it's the RM21 - just get the rotor and stator lined-up and make sure there's a good air gap all round between the two when it's all bolted up. 10 thou is ideal, though I have got away with 6 before now.
Lastly you might come across Sparx alternators which are interchangeable with the Lucas and are available in 6V, 12V and 12V three phase versions.
A.
The classic 12V single phase alternator for so many British bikes is the RM21, originally claimed to be good for 120W and to answer Davedup's original question, if it is intended as a 12V alternator then the stator will only have TWO wires, and the familiar green gunk encapsulating the windings/coils. The otherwise very similar RM19 will have THREE wires for 6V use, but these can also be wired up to produce 12V for a suitable system.
Then we get onto the Lucas high-output single-phase alternators (RM23?) @ 180W and the THREE PHASE alternators which came in 110 and 180W flavours, I believe that these all use fatter rotors and stators but are still physically interchangeable with the RM21/19. Three-phase Lucas alternators also have three wires, as well as 9 sets of windings instead of 6.
NOW we came to the Indian Bullet alternators (pre Electra-X and EFI) which are irrelevant as far as the Redditch twins are concerned, though you could fit one as an economy measure! These started off as copies of the older 3 wire Lucas (same dimensions) and were used on 6V and 12V Bullet systems, with the 4 wire alternators and AC headlights appearing in the late 90's. Lucas DID produce their own 4 wire stators with the green encapsulation, but as far as I know these were produced exclusively for our hosts as an upgrade for the Indian Bullets and were never marketed for anything else. It's possible that the E/S and Sixty-5 Bullets had beefier alternators for the extra demands on the electrics, maybe someone could confirm or deny this? There are also SIX wire Indian alternators which are still based on the Lucas design, though these are modified to provide CDI ignition on some home-market 350s.
As for whatever Davedup has been sold - I suspect it's the RM21 - just get the rotor and stator lined-up and make sure there's a good air gap all round between the two when it's all bolted up. 10 thou is ideal, though I have got away with 6 before now.
Lastly you might come across Sparx alternators which are interchangeable with the Lucas and are available in 6V, 12V and 12V three phase versions.
A.
