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Discussion Starter #1 (Edited)
1970 TR6P My Stator is 6mm out from centre of rotor. For best voltage they need to be centre. The distance piece ( 6mm), the stator studs, the rotor and the stator appear to be correct for the motor. I can only assume the crank is off a different model.
Does anyone know if its possible that there are stator studs that have a measurement 6mm shorter than the sketch attached, which would be 34.9mm instead of 40.9mm?
I could fit another distance (6mm) piece which would position the rotor correctly with the studs/ Stator position I have, but this is not a the best option as im moving the rotor further out on the crank..
Also is the duplex motor sprocket fitted correctly? Is it around the correct way? Its been on this way since I've owned the bike.
Thanks
 

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This is so common that it is almost normal.
It is definitely not the crank, they have been the same in this regard since the 50's.
Check and if necessary adjust the primary sprocket alignment first.
Then add a spacer to centralise the rotor within the stator. As long as the nut and stud have plenty of engagement, there won't be a problem.
The best info available is that a 1/4" misalignment reduces alternator output by 9%.
If you try to move the stator towards the engine, first measure the clearance to the chain, I'm doubtful there's much scope there.
 

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I spaced mine out on my 750. I used a stepped spacer that also grips the rotor alloy and helps stop the weld separation that can sometimes occur. But you need to make precise measurements to do this, it takes some care to get it right.

Don't use shorter studs for the stator.
 

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Discussion Starter #4
There is room to move the stator towards motor 6mm if i had the studs to do this. I guess I could have them made.
I was concerned moving rotor out 6mm meant the nut was not on the full depth.The idea of machining the distance piece to 12mm with a shoulder sounds ok also.
You have as usual given me food for thought.
Thanks
 

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Hi Terry,

If you haven't owned the bike since new, likely it isn't the original rotor; there have been at least two 74 mm. OD rotor widths. If you have owned the bike from new, two rotor widths were fitted in 1970 - one to triples, the other to twins and singles, your bike has always had the wrong one.

I was concerned moving rotor out 6mm meant the nut was not on the full depth.
Use one of the nuts that goes with the wider rotor? @johntioc - past Triumph dealer, currently owner of US parts wholesaler Coventry Spares - has posted previously that the most-secure rotor nut-'n'-washer are the latest parts fitted by the Co-op.

Btw, there never were "welded" rotors (magnets can't be welded, at least not if you wan't 'em to stay magnets). The rotors consist of a large hex, a wedge-shaped magnet sits on each side of the hex. and they're all held together by the material moulded around the hex. and magnets. What "tridentt150v" is alluding to is the cast material keeping hex. and magnets together comes loose from the hex., they move relative to one another during acceleration and deceleration, the otherwise-unattached (wedge-shaped) magnets are forced outwards, they don't have to extend very far beyond the rotor surface before the contact the stator ... :(

Btw, before worrying too much about the rotor/stator relationship, you might want to check that nothing's loose on the rotor - if it is, the rotor must be replaced, the new one can be a wide one and the axial relationship problem is also fixed (expensively). ;) Ideally, you need to be able to grab the rotor firmly in both hands and attempt to turn the engine with it, any movement in the rotor itself should show up/be felt.

Hth.

Regards,
 

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Discussion Starter #6
The rotor and stator are both new and are the same size as the ones that have been on it since I’ve owned it.
 

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Discussion Starter #8
Yes, crap voltage from new rotor and stator measured direct from stator, I checked it after i fitted them. A mate who's a bit of a guru on electrical told me the two should sit evenly with each other. my rotor needs to move out the thickness of the distance piece 6mm to sit evenly within stator. Or looking at it another way the stator needs to move in 6mm.
Can anyone tell me if the sprocket in the photo is fitted around the correct way? That's the only other thing that could cause a distance problem. Is it possible to have the sprocket around the wrong way? Or can it only fit on as it is? I've been told my studs are the correct size and as the rotor and stator is supposed to be correct and if the cranks are all the same I can't believe that they were built that way.
 

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While the mis-alignment will lose a bit of power, it won't produce your "crap" voltage readings.
Something else is going on here.
Much more detail about your electrical system will be needed to offer help, as well as the way in which you are testing the alternator's output.
 

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Btw, there never were "welded" rotors (magnets can't be welded, at least not if you wan't 'em to stay magnets). The rotors consist of a large hex, a wedge-shaped magnet sits on each side of the hex. and they're all held together by the material moulded around the hex. and magnets. What "tridentt150v" is alluding to is the cast material keeping hex. and magnets together comes loose from the hex., they move relative to one another during acceleration and deceleration, the otherwise-unattached (wedge-shaped) magnets are forced outwards, they don't have to extend very far beyond the rotor surface before the contact the stator ... :(

Yeah, moulded, cast or bonded might be a better term....but everyone you talk to uses the term 'welded'. Its a misnomer.
 

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Discussion Starter #11
I'm testing AC voltage on a metre direct to stator wires while motor is running. If i then plug stator to regulator/rectifier and turn low beam on i need the bike at 3000pm before the battery stops discharging. All that aside i think checking ac voltage direct from stator should be much better than it is about 1.2 volts. I'm going to pack out rotor with the spare distance piece kick it over and read the ac voltage output again and see if it makes much difference
 

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Whatever the change in construction when the "welded" myth came about, if indeed there was a change, was most likely to be in the strength of the alloy encasing the assembly. The "change" may conceivably be nothing more than improved quality control.
I've not seen an example of loose rotor disease in my friends or my own bikes in 40 years, so I reckon it is quite unusual, rather than common.
It has nothing to do with the OP's problem, which appears to be a charging issue. Reading between the lines, he has gone to the expense of a whole new alternator, presumably because the original one was suspect. Yet the new one doesn't seem to have solved whatever problem he was experiencing (I can only guess discharged battery).
That's why I asked for detailed info about the system, eg reg, rect, zener, etc and the testing method.

Unless he's been very unlucky and has got a faulty alternator, it is far more likely the fault lies elsewhere.
 

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I don't know how meaningful your testing is, without using a 1ohm load, which would produce meaningful numbers.

However, the proof of the pudding is

"If i then plug stator to regulator/rectifier and turn low beam on i need the bike at 3000pm before the battery stops discharging".

I find this fairly reasonable for the standard alternator (RM21 maybe?), what are you expecting?

If you spend more time at lower rpm you will need the high output 3-phase alternator.
 

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Discussion Starter #14
This is where it's at. Ive moved the rotor out so its centre of stator. The AC output is as follows.
At idle 600 rpm 5 Volts
2000 rpm 12.1V
3000 rpm 16 V
Another factor may be the rotor has varying gaps, 8 thou 10Thou 12 Thou 15 Thou and 16 Thou

What's the best way of entering it so its an even gap/ or near to centre as possible?

Knocking the studs this way and that looks like it would create more trouble than its worth.

I need to get the stator central of rotor to climate this as the cause.

Thanks again
 

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Hi Terry,

If i then plug stator to regulator/rectifier and turn low beam on i need the bike at 3000pm before the battery stops discharging.
Sounds about right. According to the workshop manual, a standard RM21 stator should then be generating about 9 Amps (see below). The ignition coils draw about 3.5A, as does the 40W dip filament of a original/standard/crap BPF bulb. So that's 7A; if the headlamp's on, so's the rear lamp, speedo. (and tacho.?) bulbs, blah. So what's the problem?

The problem is you haven't read the relevant part of the workshop manual, plus your "electrical guru mate" hasn't clarified anything for you.

crap voltage from new rotor and stator measured direct from stator,
I'm testing AC voltage on a metre direct to stator wires while motor is running.
At idle 600 rpm 5 Volts
2000 rpm 12.1V
3000 rpm 16 V
Your "electrical guru mate" should've told you testing just Volts meaningless; Volts are simply a measurement of the "(potential) difference" between two points - in this case the ends of the two wires from the stator.

If you look in any Triumph workshop manual, it'll tell you to test using an AC Voltmeter and a 1-Ohm resistor in parallel between the stator lead ends. The resistor makes an electrical circuit through the stator wires and coils, which means the stator generates Amps, which are one measurement of electrical work done.

The relationship between Volts, Amps and resistance (Ohms) is something called Ohm's Law - Volts = Amps x Ohms aka E=IR. Thus, the reason the resistor is "1 Ohm" is Ohm's Law means the AC Voltmeter is also indicating Amps. :thumb The Triumph workshop manual tells you what Volts/Amps the meter should indicate at certain revs.; iirc it's at least 9V @ 3,000 rpm?

There is a more-modern method of load-testing than a resistor but it escapes me for now. If you do buy a 1-Ohm test resistor from eBay, get at least a 200-Watt one and mount it on a piece of wood - resistors get very hot very quickly.

Alternatively, the quick-'n'-dirty test is to connect the headlamp bulb common and one of the filament terminals to different stator wires and rev. the engine gently; if the bulb brightens (or you blow it with too many revs.), the stator's generating.

However, as above, there's bugger-all wrong with the rotor/stator generating, the only thing "wrong" is the crap advice you've been given.

rotor has varying gaps, 8 thou 10Thou 12 Thou 15 Thou and 16 Thou
What's the best way of entering it so its an even gap/ or near to centre as possible?
Knocking the studs this way and that looks like it would create more trouble than its worth.
Nevertheless, that's how it's done. The magnetic strength of the rotor is what generates the electron movement (electricity) in the stator coils. Magnetic strength attenuates rapidly with distance so even a few thou. does make a big difference.

I've never had any success 'knocking' the stator with a rubber or similar soft mallet - ime the studs can't be moved sufficiently that their natural springiness is overcome by the gap between rotor and stator. My method is:-

. Remove both rotor and stator from the engine.

. Find a non-magnetic material of a thickness that'll space the rotor equally within the stator - e.g. if your "16 Thou" is opposite your "8 thou", you need something 12 thou. (or 6 thou. doubled up) to space space the rotor equally within the stator. Btw, aiui if the material's the right thickness, the ID of large plastic soft-drink bottles is the same as the rotor OD. Ymmv.

. Absent a large plastic soft-drink bottle fitting, make half-a-dozen or so shims from the chosen non-magnetic material and use them to space the rotor equally within the stator. Make the shims with plenty sticking out well beyond the rotor and stator outer faces

. Now attempt to fit the complete rotor-stator assembly to the engine - the rotor will fit on the crank, that stator will show which studs need moving and in which direction. Remove the rotor-stator assembly and move the offending studs gently. Repeat this procedure 'til the rotor-stator assembly slides on to the crank and all three stator studs. Bit tedious but it's doable (note "that'll do" between the stator and one or more studs will simply cause them to move the stator off the rotor centre when you pull out the shims :(). One piece of advice that's been posted in the Forum before, that I wouldn't do, is enlarge the stator holes - the risk is subsequent vibration might cause the rotor to move down 'til the top of any enlarged hole is sitting on the stud; it might only be a few thou., but a few thou. is also all there is between rotor and stator.

. When the rotor-stator assembly will slide easily on to the crank and all three stator studs, secure rotor and stator and pull out the shims; if you've done it correctly, the clearance should be equal all round. :thumb

Hth.

Regards,
 

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You wouldn't do it because you've never tried it.
I've used that method for years and I probably rev my motors much more and for longer than anyone else here and there are zero problems

OCR
 

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Discussion Starter #17
The new stator is 16amp could that have anything to do with it, it was advertised and sold for my bike but I just noticed in the workshop manual the original was 10amp
 

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Discussion Starter #18
My terminology may have been confusing, I’m testing alternator open circuit.I have refitted old 10 amp stator and the reading is the same as the 16amp, the figures I stated earlier. Only thing I haven’t done yet is Center ing rotor using shims as suggested.
 

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Hi Terry,

My terminology may have been confusing, I’m testing alternator open circuit.
Not confusing. Testing anything "open circuit" is pointless, doesn't tell anyone anything; waste of your time doing it and posting about it.

Otoh, that you've connected the alternator to the reg./rec., run it and the bike's Ammeter shows a decreasing discharge from the battery "before [it] stops discharging" above 3,000 rpm shows the alternator is working.

Both "koan38" and I have laid this out for you based on the "10 amp" standard Lucas RM21 alternator fitted to your bike when it was new and an "original/standard/crap" 45W main/40W dip headlamp bulb. If the headlamp bulb is more powerful. or anything in my post #15 isn't clear, please advise.

Otoh, "If i then plug stator to regulator/rectifier and turn low beam on i need the bike at 3000pm before the battery stops discharging" was the "new ... 16amp" stator, this appears dubious, in that "the new ... 16amp" stator doesn't appear to be generating any more than the original "10 amp" stator? :(

Fwiw, if you'd posted before lashing out on a "new ... 16amp" stator, I would've advised against; ime they're more trouble than they're worth, there are other, better, tried-and-tested ways of getting more electrical power on an old Britbike.

Hth.

Regards,
 

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Discussion Starter #20
I will check the globe tomorrow I think it might be bigger than the 35/45 in the manual, will confirm
 
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