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Discussion Starter · #1 ·
Hi again everyone I have just purchased an encapsulated green 12v alternator stator from a 1970's norton to replace the older bare coil type stator on my pre unit triton but of course all three wires are coloured differently on the bike I have green/yellow, green/white, and green/black on the old stator I have yellow, red, and green on the replacement stator can anyone assist me by telling me how this should be connected many thanks Chris
 

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Hi Chris,

Firstly, welcome to the Forum. :)

Mmmm ... unfortunately, "yellow, red, and green" aren't standard wiring colours for a 1970's Notrun, so it's a later pattern stator ...

"a 1970's norton" must be a Commando; as standard, they were fitted with 2-wire single-phase stators, usually the 10.5A @ 5,000 rpm RM21 but the 14.5A @ 5,000 rpm RM23 was an option before the electric-start Mk.3 850 and standard on them.

Working on the assumption that only a really stupid owner would've paid for a 3-wire single-phase stator that was less-powerful than even an original RM21, an educated guess says "three wires" indicate a 3-phase stator. You might be able to confirm this by looking at the inside circumference of the new stator; if you can see the ends of the stator coil cores (look different from the laminations that make up the stator outside the green encapsulation material) and there are nine of them, you have a 3-phase stator.

Otherwise you need to get back to the seller and find out what the stator was connected to (rectifier, Zener diodes, combined reg./rec., etc.) and how it was connected; unfortunately, you can't simply connect the three wires on a 3-phase stator to the the three wires on your bike already. :(

Because, despite the three wires on your Triton's stator, that it's "bare coil type" means it's single-phase; if your bike has 12V electrics, the existing stator is connected to the rectifier or reg./rec. with the Green/Yellow and Green/Black wires together and the Green/White separate.

It would also help to know what rectification and regulating components your're using - separate rectifier and Zener diode, combined reg./rec., etc.?

Hth.

Regards,
 

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Discussion Starter · #3 ·
It seems I may not have the right one at all it only has 6 contact points showing on the inside circumference so I assume your advice is to return it, what model would be best suited to my purpose ? With the old stator and smaller rotor it is running through a separate Zener diode and separate rectifier many thanks for your knowledgeable reply Chris
 

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Hi Chris,

Working on the assumption that only a really stupid owner would've paid for a 3-wire single-phase stator that was less-powerful than even an original RM21,
it only has 6 contact points showing on the inside circumference
Ok, a really stupid owner then ... :whistle

I assume your advice is to return it,
Depends how much more money you want to spend:- :)

. If we can work out which stator wire colours correspond with the "green/yellow, green/white, and green/black", the encapsulation should mean it'll be more reliable than your bike's original stator, and it should provide a little more power; but are you going to need a later standard 74 mm.-o.d. rotor to get the required 8 thou. to 12 thou. clearance between rotor o.d. and stator i.d.?

. Otoh, if you've got to buy a rotor, would you be better returning this stator and buying a new modern stator and rotor - you have the options of more-powerful single-phase and using your existing Zener and rectifier or more-powerful single- or 3-phase with a new combined reg./rec. replacing the rectifier and Zener.

Hth.

Regards,
 

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Discussion Starter · #5 ·
I will have to bite the bullet and buy new what is the best model for me to get using the rest of the kit already mounted and all 3 wires were being used unless they are joined somewhere along the loom the bike was running at 12v as all the bulbs are 12v thanks again from the stupid owner Chris
 

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As Stuart already mentioned the best bet for your bike is 1 phase, six coils, two wire stator.
But if you can't return your new stator to the vendor, can it work with your rotor ?
In this case it's possible to connect 3 wires of your stator in the way it works as 2 wire stator.
 

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Discussion Starter · #7 ·
It came with a rotor so that is not a problem but power output will be very low from this type Chris
 

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Hi Chris,

the bike was running at 12v as all the bulbs are 12v
That's "12v" DC (Direct Current). Nothing to do with the alternator, which produces AC (Alternating Current). As you've posted that your bike has a separate rectifier and Zener diode, the rectifier turns (rectifies) the AC into DC and the Zener regulates it, by converting AC more than a little above nominal (~15V on a "12v" system, ~7.5V on a '6V' sysrem) into heat.

Note, just for cheapness, a single Zener must be connected on the DC side of the rectifier but, when two or more are used, they can regulate either the AC or the DC.

Digressing, hopefully for greater clarity:-

. When your bike's existing alternator was connected originally, the original bike's electrics were 6V DC. As Zeners weren't available 'til the mid-1960's, and then only 12V at first, 6V regulation was by the battery and a complex set of connections through either a PRS8 combined ignition and lighting switch, superseded in the early 1960's by separate ignition and lighting switches like 88SA and 41SA. Only the ignition and battery-charging current were rectified, the headlamp and 'emergency' ignition (separate position on the ignition switch) were supplied raw AC direct from the alternator stator.

. One of the reasons British motorcycle makers changed quickly to 12V electrics in the mid-1960's was that availability of 12V Zeners - simple and reliable, they allowed deletion of the complicated AC/DC supply circuitry and substitution of the complex switches by simpler (cheaper) ones.

all 3 wires were being used
The original reason for 3-wire single-phase alternators were the stator coils were divided into 'ignition' - connected by the Green/Black wire to one side of the rectifier, output then rectified to DC to supply the ignition and charge the battery - and 'lighting' - connected by the Green/Yellow wire direct to either the ignition or lighting switches, to supply the headlamp, and the ignition from the 'emergency' position on the ignition switch. Green/White (or White/Green) is common to the other ends of both divisions and is connected to the other rectifier terminal.

When Lucas and the motorcycle makers changed to 12V electrics, they still continued to use the 3-wire single-phase alternator (by then the RM19 and RM20). Different motorcycle makers used slightly different configurations, the simplest of which was to connect the alternator stator Green/Yellow wire to the same rectifier terminal as the Green/Black, thus rectifying the AC output of all six stator coils to DC at all times. The only major reason I know of not to this is if your bike uses a magneto for ignition.

When Lucas superseded the RM19 and RM20 with the RM21, 22 and 23, the latter were still six coils and single-phase but with only two external wires (Green/Yellow and White/Green); what had been separate stator coil connections to be made externally as a motorcycle maker decided were simply internal.

what is the best model for me to get using the rest of the kit already mounted
I'm assuming the existing rectifier has four terminals (if an original with three almost-circular plates mounted on a central stud, the stud itself is the fourth terminal)? If so, as posted already, you're limited to 2-wire stators.

power output will be very low from this type
Not so. As I posted earlier, the RM23 produces 14.5A @ 5,000 rpm (Norton quoted 15A @ 6,000 rpm) and some of these stators might still be available. In any event, Wassel (aka "Genuine Lucas" :rofl) offer alleged '16A' and '20A' pattern versions, though without any rpm qualification and afaik no-one who's tested one has seen these Amps at any rpm a Britbike can manage without converting to a 3D version of the parts book ...

Nevertheless, any will produce considerably more than the existing alternator ... :D If a dealer like Grin can't turn up what's now known as a 'Made In England' RM23 stator (Wassell's licensing agreement with TRW - the owners of the "Lucas" brand - forbids use of the "Lucas" name to advertise components not made by Wassell :rolleyes:), the Wassell "16A" 2-wire stator is as good as it gets ... :bluduh I advise against the "20A" version simply because a Zener's only good for about 12A~12.5A; the ignition coil(s) of a running engine consume(s) about 4A, 16A less 4A equals 12A ... Ish. :)

if you can't return your new stator to the vendor, can it work with your rotor ?
In this case it's possible to connect 3 wires of your stator in the way it works as 2 wire stator.
Problem with that is, as I posted earlier, given the stator Chris is working with has non-standard wire colours, will be working out which wire is connected to the 'ignition' stator coils, the 'lighting' coils and the 'common' one. :( If all the stator coils are all the same resistance, the 'ignition' coils' resistance should be be half that of the 'lighting' coils'.

I can write up the test sequence but, even then, the stator could well be not particularly powerful. :(

Hth.

Regards,
 

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Discussion Starter · #9 ·
Please forget the stator I started this post about I cannot identify the wires and do not believe the output is high enough anyway so that is going back from whence it came, what I would like is a simple cure to this problem so if anyone can let me know exactly what I need model no etc and how to connect once I have got it, so I hopefully manage to grab a bit of this summer on the bike many thanks again Chris
 

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Hi Chris,

what I would like is a simple cure to this problem so if anyone can let me know exactly what I need
and how to connect once I have got it,
Errrm ... you haven't answered my questions:-

Does your bike have a magneto for ignition?

I'm assuming the existing rectifier has four terminals (if an original with three almost-circular plates mounted on a central stud, the stud itself is the fourth terminal)?
Regards,
 

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Discussion Starter · #11 · (Edited)
Apologies no it does not have a magneto at the moment it has an old distributor and coil but a rebuilt engine is making its way to me with Boyer Bransden kit, the rectifier mounted under the seat has 3 terminals and is numbered 49072A and has another number on it 6603 thanks again Chris
 

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Discussion Starter · #13 ·
That sounds about right for the rectifier lucas 49072A with another number 6603 thanks again for putting up with my ignorance Chris
 

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Discussion Starter · #14 ·
Hi again everyone and Stuart I have just found this stator on ebay in the UK will it do the job or will it also give me problems connecting thanks Chris
LU47252 - Genuine Lucas 47252 RM24 12V 3 phase Stator
 

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Hi Chris,

rectifier lucas 49072A
LU47252 - Genuine Lucas 47252 RM24 12V 3 phase Stator
will it do the job or will it also give me problems connecting
It will give you problems connecting.

You've confirmed my assumption in an earlier post about the rectifier; it has only four terminals - two (mounting and middle plate) are DC +ve and -ve respectively.

A 3-phase stator has three AC wires, each of which must be connected to its own AC input on a rectifier or reg./rec.; you cannot join two wires as you can with a 3-wire single-phase stator.

Otoh, the bike's existing rectifier has only two AC inputs - the top and bottom plates. As I posted earlier:-

you're limited to 2-wire stators.
If a dealer like Grin can't turn up what's now known as a 'Made In England' RM23 stator
the Wassell "16A" 2-wire stator is as good as it gets ...
I advise against the "20A" version simply because a Zener's only good for about 12A~12.5A; the ignition coil(s) of a running engine consume(s) about 4A, 16A less 4A equals 12A ...
Hth.

Regards,
 

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Discussion Starter · #16 ·
Thanks a lot Stuart for putting up with me I am in the process of ordering an RM23 as we speak but still a bit confused as to which wires I join together and where I join them on the bike thanks again Chris
 

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Discussion Starter · #17 ·
Hi Stuart and others I have now ordered this GENUINE LUCAS 47239 STATOR - RM23 2 LEAD SINGLE PHASE 16 amp - LU47239 which I understand will do the job but would like to know how and where to connect the 2 wires as mine was running 3 wires but 12v many thanks hope I can now put this to bed Chris
 

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Hi Chris,

Apologies for the delay replying. Wednesday I was ticking one of the boxes on my Significant Birthday (hopefully not Bucket :eek:) List - Bruce Springsteen at Glasgow. :doublethumb Between the concert and the drive each way, a 14-hour round trip, I didn't get home 'til 3 am so a bit knackered yesterday.

ordered this GENUINE LUCAS 47239 STATOR - RM23 2 LEAD SINGLE PHASE 16 amp - LU47239 which I understand will do the job
If it's described as "GENUINE LUCAS" and "16 amp", it's Wassell; don't kid or let yourself be kidded otherwise. Prepare yourself for fitting problems then you'll be pleasantly-surprised if you don't have any. Don't tolerate any fitting problems - you shouldn't need hammer, files or other bodging tools to fit it; bear in mind you can't send it back it you've hammered, filed or otherwise bodged it.

That said, one fitting problem you could have even with original Lucas rotors and stators was getting them concentric for an even clearance all round. The clearance should be between 0.008" and 0.012" (colloquially known as 'eight thou' and 'twelve thou').

If you don't have the clearance all the way round immediately you fit the stator, I can tell you for nothing that bending the stator mounting studs independently is an exercise in futility. :gah The method I use is one I read on the BritBike forum years ago:-

. Remove both rotor and stator from the bike and insert the rotor in the stator; they'll stick together in one area, measure the greatest clearance opposite.

. Make up five or six shims from sheet metal - one good source is aluminium drinks cans, 'cos the ally won't stick to the rotor. Depending on the metal thickness and the desired clearance (half the measurement you got previously), you might have to fold bits of sheet in half. Whatever you do, make the shims big enough that they stick out generously from the rotor/stator joint.

. Push the rotor out of the stator and reinsert it with the shims around it; a trained octopus that isn't offended by raw Anglo-Saxon can be useful for this stage ...

. When you have the rotor shimmed concentrically in the stator, offer up the whole assembly to the crank and stator mounting studs. It's unlikely to slide on first time but it indicates the direction and amount individual studs need to be pushed/bent. It's time-consuming but what you're aiming for is a sliding fit of crank into rotor and mounting studs into upper part of stator holes (so the stator weight doesn't cause it to slide down on to one or more studs - you only have clearance in thousandths of an inch). Don't be tempted to go for "it'll do"; any force used to fit the rotor/stator assembly will cause the stator to move laterally when you pull out the shims ... :bluduh

. When you have the desirable sliding fit on crank and all stator studs, fit the assembly and all nuts 'n' washers and tighten.

. Finally, sacrifice a virgin or whatever, pull out the shims (now you see why I said they should "stick out generously", so you can get a decent grip on 'em :)) and check and recheck the rotor/stator clearance with the rotor in different positions. If she really was a virgin, you'll have equal clearance all round; :doublethumb if she wasn't, you'll have to start over. :gah

would like to know how and where to connect the 2 wires as mine was running 3 wires but 12v
The on-line pictures I can find show White/Green and Green/Yellow wires; connect them to the same colours on your bike already, that should be connected one to each AC terminal on the rectifier.

The third wire on your bike is Green/Black; it's either connected to the Green/Yellow wire or the same rectifier terminal? It's now redundant; if you can remove it easily, do so; otherwise just tape up the ends securely.

Hth.

Regards,
 
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