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Hi Terry,

I will check the globe tomorrow I think it might be bigger than the 35/45 in the manual, will confirm
:) Strictly-speaking a whole 'nother discussion but:-

. Lucas supplied/Triumph fitted to the twins: 50/40 (Watts main/dip) pre-'71, 45/35 '71-'77; "TR7RVMan" Don has posted much greater detail but, essentially, while either bulb will fit any lens/reflector with a BPF (British Pre Focus) fitting, the two bulbs and lens/reflectors are different, and mixing the two will only give even crappier focus.

. Nevertheless, all BPF are still only degrees of crapiness. :( Significantly- and visibly-better focus is only available either with a '78-on lens/reflector and P45t-base bulb (45/40 on Triumphs), or a modern lens/reflector and P43t-base bulb.

Specific to the alternator-testing discussion, none of the original main or dip filaments draw significantly-more or -less Amps than the others (the relationship is Watts = Amps x Volts). Each filament in a 60/55 quartz-halogen bulb draws ~1 Amp more; the only headlamp bulbs that'd make a significant difference to testing would be the 80W-90W-dip/100W-130W-main ones.

Hth.

Regards,
 

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Discussion Starter #22
I think I've made the mistake of assuming the brand new rotor I bought was 100% I compared the strength with the old one and its noticeably less. I will try re magnetising the new rotor and see what happens before I do anything else. Stewart, trying to line up the studs is a job and a half but im getting there.
 

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Discussion Starter #23
I assumed the new rotor was 100%, it has been the last thing I have checked and should have been the first. The link below to Lucas Alternators, the article explains if the magnetism of rotor is poor you get exactly the same circumstances im getting. After testing the rotor it has less pull than my old one. I'm going to start by re magnetising my new one and go from there.

https://jrcengineering.com/technical-support/lucas-alternator-tips/

Will let you know how it goes
 

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Hi Terry,

I'm going to start by re magnetising my new one and go from there.
Ime, 'fraid you could well be wasting your time and money. Aiui, remagnetising a rotor is difficult, I can't recall anyone ever posting in the past it was successful, possibly because there are actually six separate magnets, that were originally magnetised separately before being buried in the non-magnetic casting?

If the old rotor is "stronger" than the new one, why not just use that and take/send back the new one to the seller for a refund, instead of throwing more of your money at a problem that isn't yours? :confused:

Regards,
 

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If you have a local "re-magnetising shop" you're living in a more convenient universe than I.
Is it too late to send the rotor back?
It still begs the question, what was the original problem, if indeed there was one?
 

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Hi,

what was the original problem, if indeed there was one?
While Terry hasn't filled in all the gaps, I think he thinks, with a "16A" stator and headlamp on, he shouldn't have to rev. the engine to 3,000 rpm for the Ammeter to show the battery being charged.

To give definitive advice, we'd need to know at what rpm these alleged 16 Amps are produced; afaik, Wassell have never published this information?

We'd also need to know the Watts of the headlamp filament in use; confirmation that other lamps are on or off would be useful also.

Regards,
 

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Discussion Starter #27
The old rotor has some damage from someone working on it in the past, i don't want to risk re fitting it.
My mate's helping me with re magnetising the new rotor, we are making up a jig, he's done this before, did his trade in the railways many years ago.I will let you know how it goes.
Reading the lucas article (address below) it describes my symptoms exactly.
I don't think i will pack out rotor as it appears easier to keep the gap even with the stator. I think it being further out on the shaft my give a tendency for the minutest of a wobble.
I did get the gap reasonably even with the standard 6mm distance piece, had it on and off about a dozen though to get it correct. Couldn't get it accurate with the extra distance piece no matter how much i tried.

https://jrcengineering.com/technical-support/lucas-alternator-tips/
 

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Have you ever just fitted the rotor - sans stator - and used a dial gauge on it??? It should rotate almost perfectly with no run out. If you are getting run out then you have a bent crank snout, which would need expert attention. I am only saying this because your rotor clearance shouldn't change once properly set and no matter where it sits on the crank. Once it is pressed on and the nut is also used it should be centred.
 

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Have you ever just fitted the rotor - sans stator - and used a dial gauge on it??? It should rotate almost perfectly with no run out. If you are getting run out then you have a bent crank snout, which would need expert attention. I am only saying this because your rotor clearance shouldn't change once properly set and no matter where it sits on the crank. Once it is pressed on and the nut is also used it should be centred.
He wouldn't be the first person to get an egg shaped rotor...
I have a special mandrel I use to check/turn/correct them on the lathe.
 

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Hi Terry,

the lucas article (address below) it describes my symptoms exactly.
https://jrcengineering.com/technical-support/lucas-alternator-tips/
The article has several errors:-

Testing output on a running machine in this way. You will need an ammeter for the first test. Any old automotive unit will do or a Pep Boys cheapo replacement type. Connect leads to the ammeter and install alligator clips on the ends.
Remove the center Brown/blue wire from the rectifier. Connect the ammeter in series with the rectifier and the brown/blue wire that was plugged on to that terminal. Start the bike. The ammeter should show a discharge of 1-2 amps at idle speed. The needle should move to charge as you increase engine RPM to 2000 rpm. The needle should show a charge of 1-2 amps at 2200 rpm. Now switch the lights on. There should dip in charge rate followed by moving back to positive above 2200 RPM. If the needle shows no charge recheck all connections or components. If it takes 3000RPM or more to begin showing a charge then the Rotor may be demagnetized or the stator may have 2 dead coils. Check the stator coils as described above.
. "Remove the center Brown/blue wire from the rectifier." '70, if your bike has an Ammeter mounted in the headlamp shell, the wire - specifically attached to the centre terminal of the rectifier - is Brown/White.

. "Connect the ammeter in series with the rectifier and the brown/blue [or Brown/White] wire that was plugged on to that terminal. Start the bike. The ammeter should show a discharge of 1-2 amps at idle speed. The needle should move to charge as you increase engine RPM to 2000 rpm. The needle should show a charge of 1-2 amps at 2200 rpm."

Major :Dang

Wiring diagrams in Triumph and Lucas manuals represent the rectifier as four:-



... this specifically indicates that current can only pass through the diode in ONE direction, which is a specific property of diodes.

For an Ammeter "connect[ed] in series with the rectifier and the [brown/blue] wire" to "show a discharge of 1-2 amps at idle speed" and then "move to charge as you increase engine RPM to 2000 rpm.", current would have to pass through the rectifier diodes in both ("discharge" and "charge") directions ... :Darn If it does, the rectifier is donald.

Likely Bill The Writer is confused with the standard pre-'71 Ammeter installation:-

. Brown/Blue from battery -ve is connected to one Ammeter terminal.

. Brown/White from the rectifier is connected to the other Ammeter terminal, and one ignition switch terminal.

. Consumers such as the ignition coil/s is/are connected by the White wire/s on the other ignition switch terminal.

. Turning on the ignition switch connects Brown/White wires to White wires; certainly the ignition coil/s draw/s Amps, usually ~3.5A. If the Brown/Blue and Brown/White wires are connected to the correct Ammeter terminals, the Ammeter needle will swing from central zero towards the "-"; this is a "discharge" from the battery (not the rectifier) because you haven't started the engine.

. Lucas motorcycle alternators (like most motorcycle alternators) are known as "permanent magnet", because the rotor is permanently-magnetised (unlike nearly all other alternators, where the rotor is an electro-magnet, allowing output to be varied by increasing/decreasing the Amps through the rotor, which increases/decreases the magnetic strength of the rotor).

. Electricity and magnetism are inextricably linked. If you pass an electric current through a piece of metal, the piece of metal will have a magnetic field around it. More particularly for permanent-magnet alternators, if you wave any magnet near a piece of metal, the magnetism induces an electric current in the piece of metal.

. Amps are the units of electric current. So, once you start a permanent-magnet alternator rotor spinning, the alternator is generating AC (for clarity, this does require an electrical 'load' across the alternator stator, but that's been covered already (testing with a resistor) in this thread; your bike's DC electrics connected through the rectifier are also "an electrical 'load'").

. However, permanent-magnet alternators generate more only the faster the rotor's spun - that's why 'original Lucas' rated theirs "x Amps @ 5,000 rpm". However2, the relationship between rpm and generated Amps isn't linear - that's why 'original Lucas' advertised "75% of rated @ 2,400 rpm" for the single-phase RM21 and RM23.

. So, @ tickover rpm, a Lucas alternator doesn't generate very much. Nevertheless, if you were to connect an expensive high-end Ammeter in series between the rectifier's DC output and either its pre-'71 Brown/White wire or '71-on Brown/Blue wire, the meter would show the small tickover DC output ("charge") from the alternator/rectifier.

. This small tickover DC output from the alternator/rectifier is less than the ~3.5A drawn by just the ignition coils. Therefore, @ tickover rpm, (most of) this ~3.5A is still drawn from the battery; on a pre-'71 Britbike like yours Amps drawn from the battery pass through the standard Ammeter, which is precisely why the standard Ammeter still indicates a "discharge" at tickover.

. As engine rpm is increased, the alternator generates more. So less is drawn from the battery to supply the consumers (ignition coils, lamp filaments, etc.), which is why the standard Ammeter's needle moves from "-" back towards zero as engine rpm increases.

. Eventually - as you've noticed already - at some rpm (dependent on the consumers switched on), the standard Ammeter's needle moves past central zero towards "+". This indicates both the alternator is generating enough to supply all the consumers switched on and more to charge the battery.

To summarise:-

. An Ammeter connected between a rectifier's DC output terminal and the rest of a vehicle's DC electrics cannot indicate a "discharge" (from another source like the battery) unless the rectifier itself is faulty.

. The standard pre-'71 Britbike Ammeter connected between battery, rectifier and ignition switch can indicate both "discharge" (from the battery) and "charge" (from the rectifier into the battery).

Also Emgo and Lucas offer replacement Rotors and stators that have proven reliable in service. In addition These companies have taken advantage of modern components to offer 180 watt units to replace the 120W Lucas components.
Load of cobblers. :bluduh

'Original Lucas' always offered higher-output versions of alternators as long as British motorcycle makers made special versions for particularly the police; I've a copy of a rpm/Amps graph from the Lucas Archive at the British Motor Museum of a version of the 1960's (i.e. "modern" over half-a-century ago :rolleyes:) 3-wire single-phase (RM19/RM20) producing ~15A @ 5,000 rpm ...

The original "10 amp" ("120W") stator on your bike was a RM21, which Lucas first produced around 1969; the identical-looking RM23 stator was "180 watt" (14.5 Amps @ 5,000 rpm). While neither Triumph nor BSA did, Norton offered the RM23 as an option on 'civvy' Commandos and fitted it as standard to the '75 Mk.3 850 with electric-start.

When 'original Lucas' superseded the RM21 and RM23 single-phase stators with the RM24 3-phase during 1978, both "120W" (aka "low output") and "180W" (aka "high output") versions were made (my T160's have both had the latter since 1982/3, nothing to do with either Emgo or 'Wassell Lucas' :cool:). The Co-op fitted the low-output 3-phase as standard '79-on to kickstart bikes, the high-output was available as an option and fitted as standard to electric-start bikes.

Btw, nothing to do with Emgo or 'Wassell Lucas', a British company also makes alternator components (arguably not 'pattern' as the company could show a connection to 'original Lucas' in GB :D). 'Wassell Lucas' prohibits the maker or retailers from mentioning "Lucas" either on the components or in listings, so they're known/listed simply as "Made In England" or "Made In UK" ...

Hth.

Regards,
 

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This indicates to me a problem with the new distance piece, and perhaps not the crank.
Not sure how RPW? The distance piece behind the rotor shouldn't affect the rotors' run out......arrgh brainwave...unless the distance piece isn't true/flat. If its wedged then it could pull the rotor out once torqued up??? maybe???
 

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Not sure how RPW? The distance piece behind the rotor shouldn't affect the rotors' run out......arrgh brainwave...unless the distance piece isn't true/flat. If its wedged then it could pull the rotor out once torqued up??? maybe???
I had this problem on a pre unit fitted with reproduction chaincase. The problem turned out to be the drilling's for the stator carrier mounting studs was slightly out, yours should not be but it may be worth checking. Forget about the distance spacer for now. The first line of attack is to ensure the rotor is round & runs parallel in the stator. Everything else checked (stub not bent, sprocket not sloppy, crank bearings sound, spacer square, rotor light press fit, etc), use an equal continuous shim as suggested earlier between clamped up rotor and unfastened stator, (tight as possible without force), press home the stator over the rotor, measure, or use equal lengths of tube under the mounting holes and check each has equal bearing between the case and stator, if not that's the first problem to rectify. each 5/16" stud stator bearing level has to be reasonably the same, shims can help. Reassemble and it should be OK. If the problem persists, then theirs a bigger problem:-

Insert a 5/16" close fitting turned shaft, turned square and engineers blue on the end, This will tell you roughly if the holes line up correctly, if not the blue will leave witness marks to one side of all the holes indicating the location of misalignment. If so, I'd agree with not trying to 'adjust' the studs forcibly, and it's very difficult to adjust by drilling a hole with the required tolerance in laminated steel.

In my case (and I agree it's a botch), the studs (slightly different set up with screws on a pre unit stator carrier) were turned down slightly about 0.005" under head and the thickness of the stator, so slight adjustment was available until the final 'nip up'. Each fastener got a coat of low bond just (in the hope) it would reduce any hollow. In practice, if the stator is going to move, it will anyway with normal clearances, it's a case of how much.

It seems quite a common problem and I don't know whey a cam collar adjuster was never employed to make life easy.
 

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Not mine...sorry if I gave that impression, like you, I was problem solving for the OP. For the record all my setup's are fine, no stators and rotors were injured in the making of this reply :)
 

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Discussion Starter #35
Well, problem solved. I left the rotor with the one 6mm distance piece and replaced the rotor with another new one. It seems it was simply the new rotor i bought was faulty with the magnetism being about 2/3rds what it should have been.
We tried to re magnetise the faulty rotor but basically the strength of magnets are limited to the quality of the material they are made from and it could not be strengthened more than it was.

The link below from lucas has some checks for anyone experiencing similar problems with a couple of simple places to start.

https://jrcengineering.com/technical-support/lucas-alternator-tips/

Thanks everyone for your time and advice
 

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Hi Terry,

The link below from lucas has some checks for anyone experiencing similar problems with a couple of simple places to start.
https://jrcengineering.com/technical-support/lucas-alternator-tips/
JRC Engineering is not "lucas" and, as posted already:-

The article has several errors
problem solved. I
replaced the rotor with another new one. It seems it was simply the new rotor i bought was faulty with the magnetism being about 2/3rds what it should have been.
Which is not in the JRC "article" ...

Regards,
 

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Discussion Starter #37
Below is where the article referred to my exact symptoms.

Start the bike. The ammeter should show a discharge of 1-2 amps at idle speed. The needle should move to charge as you increase engine RPM to 2000 rpm. The needle should show a charge of 1-2 amps at 2200 rpm. Now switch the lights on. There should dip in charge rate followed by moving back to positive above 2200 RPM. If the needle shows no charge recheck all connections or components. If it takes 3000RPM or more to begin showing a charge then the Rotor may be demagnetized or the stator may have 2 dead coils. Check the stator coils as described above.

I'm not sure what other errors were in the article the one that referred to my symptoms were spot on though. I thought this was an article from the Lucas website, sorry my mistake it can get confusing what your reading sometimes.
 

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Hi Terry,

Below is where the article referred to my exact symptoms.
Start the bike. The ammeter should show a discharge of 1-2 amps at idle speed. The needle should move to charge as you increase engine RPM to 2000 rpm. The needle should show a charge of 1-2 amps at 2200 rpm. Now switch the lights on. There should dip in charge rate followed by moving back to positive above 2200 RPM. If the needle shows no charge recheck all connections or components. If it takes 3000RPM or more to begin showing a charge then the Rotor may be demagnetized or the stator may have 2 dead coils. Check the stator coils as described above.
... is preceded by:-

Remove the center Brown/blue wire from the rectifier. Connect the ammeter in series with the rectifier and the brown/blue wire that was plugged on to that terminal.
To summarise:-

. An Ammeter connected between a rectifier's DC output terminal and the rest of a vehicle's DC electrics cannot indicate a "discharge" (from another source like the battery) unless the rectifier itself is faulty.
As standard on any pre-'71 Britbike:-

. The "center ... wire from the rectifier" is Brown/White, not Brown/Blue. Brown/Blue is only between one Ammeter terminal and the battery -ve terminal (and one horn or horn relay terminal).

The standard Ammeter on any pre-'71 Britbike is not "in series with the rectifier and the brown/[White] wire that was plugged on to that terminal".

The JRC text you've quoted and your "exact symptoms" are precisely what the standard Ammeter on any pre-'71 Britbike always shows.

I'm not sure what other errors were in the article
https://www.triumphrat.net/2003899624-post31.html.

Hth.

Regards,
 

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Discussion Starter #39 (Edited)
Just an update for what it's worth.
I fitted a new rotor as the one I had (although new) had very poor magnetism so ended up in the bin as the seller wouldn't refund the money. The system now recharges the battery even though I ride with the headlight on.
It is also possible to remagnetise if you know what your doing, we tried and even reversed the polarities but the material it is made from governs the amount of magnetism you can attain apparently.

So the lesson is, DON'T ASSUME BECAUSE IT'S NEW IT'S NOT FAULTY
 

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Discussion Starter #40
Since I replaced the rotor my system is now fully charging the battery even after riding all day with the headlight on. Very happy with outcome
 
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