Repolarisation of Magneto/ Stator- Rotor?

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Repolarisation of Magneto/ Stator- Rotor?

Postby bikestyles » Sat Nov 11, 2017 9:48 am

Hello to you all fantastic electric gurus..

Finishing a 1971 B50 MX - CCM <069 ccmicon whatever I have put on genuine alternator- rotor and coil- points. Turning clockwise it makes a nice spark, turning it in the right direction (ANTICLOCKWISE) I get none independing whatever circuit I use. Even turning the rotor and/or alternator has no influence. It sparks in the wrong direction ONLY ONLY ONLY ONLY ONLY ONLY. >44

So I think <213 that one of the two parts may lost its magnetic direction.

Have anybody any clue wether it is possible to remagnetise them by turning them in the GOOD <214 direction with a big and strong battery connected to THE POLES?

PS: I do not believe that this a predictable hint for the earth magnetic field to change.. :werd
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Re: Repolarisation of Magneto/ Stator- Rotor?

Postby CCM620 » Sat Nov 11, 2017 10:11 am

off Topic: Büssing !

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Re: Repolarisation of Magneto/ Stator- Rotor?

Postby minetymenace » Sat Nov 11, 2017 10:36 am

One of two things, either your stator/rotor is out of phase. The order is:
1. The pole of the rotor sweeps past the ignition coil (on the stator) and the voltage builds
2. The points open and the rapid collapse of the voltage generates your spark.

If you have this working the other way round, no spark.

I'm not familiar with the MX ignition, so don't know if the rotors are the same as the battery/capacitor, coil, points powered ignitions, this is worth checking, you may have the wrong rotor (but doubt it). I suspect you have the stator in the wrong position.

Repolorisation of the magnets is unheard of.
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Re: Repolarisation of Magneto/ Stator- Rotor?

Postby stew79 » Sat Nov 11, 2017 12:36 pm

there are many different ignition parts that all look roughly the same, but do not interchange. to get the right parts in the right order, and set correctly will only just be good enough. (with a good bump start !) why not fit an electronic ignition ?
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Re: Repolarisation of Magneto/ Stator- Rotor?

Postby bikestyles » Sat Nov 11, 2017 1:49 pm

First: Büssing with its mass has no influence on the BSA magnetic field (HOPEFULLY). IHOSMILE In case if I let you know :laugh

And thanks, I will check monday the points opening question. :ban

Can anybody give me the correct number that must be on the rotor to go with the half-moonish MX alternator. :roll:

Any more hints and solutions...

Cheers S. from Berlin, where the northpole seems to be sometimes downunder

<201 <201 <934 <974 <018 <018 <018 <018 <002 <001
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Re: Repolarisation of Magneto/ Stator- Rotor?

Postby beat » Sat Nov 11, 2017 7:14 pm

bikestyles wrote: I think that one of the two parts may lost its magnetic direction.


I don't think so.

guess you are in a wrong position with something..... &lt;069

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Re: Repolarisation of Magneto/ Stator- Rotor?

Postby bikestyles » Sun Nov 12, 2017 12:26 am

Ok,

just again. This is a serious problem to me and I have tried stator and rotor in all positions, and the wiring. If it sparks, than only backwards. :shock:
So can anybody help me with the imprinted rotor number for an MX ignition. :idea:

I am on the bike late Monday night again..
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Re: Repolarisation of Magneto/ Stator- Rotor?

Postby minetymenace » Sun Nov 12, 2017 12:42 am

Think you need to post some pictures, something is wrong and you can't see it, let us have a look please.
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Re: Repolarisation of Magneto/ Stator- Rotor?

Postby clive 54 bsa » Sun Nov 12, 2017 9:05 am

Bikestyles, here's a photo of mine, hope you can read the numbers.
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Re: Repolarisation of Magneto/ Stator- Rotor?

Postby kommando » Sun Nov 12, 2017 10:25 am

If you take the stator off its studs and put it on the opposite way then the stator will see the rotor from the different direction. These ET systems were notorious for needing the magnets to be passing the coils at just the right time, earlier versions were not driven off the keyway but from holes drilled into the back of the rotor and you selected the one that gave the best spark, you then cannot strobe the bike without making marks for the correct timing.

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Re: Repolarisation of Magneto/ Stator- Rotor?

Postby bikestyles » Sun Nov 12, 2017 12:03 pm

Many Thanks for the picture. <038

Some friends call me SIXEYES because of me wearing two glasses sometimes to look at things.. <119

AND YES I have tested all four possible positions off stator and rotor. EVEN IF ROTOR "RUNS" oppposit and BACKWARDS IT SPARKS BACKWARDS ONLY. <128
AND YES I have tested all other logical wirings... <205


<214 <214 <214 <214 <214 <214 <214 <214 <214
I will check the number tomorrow and put on another coil and let you know.
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Re: Repolarisation of Magneto/ Stator- Rotor?

Postby midgie » Sun Nov 12, 2017 3:02 pm

You have the correct rotor, but these ET systems have to be turned over fast before you can even see a spark in my experience.

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Re: Repolarisation of Magneto/ Stator- Rotor?

Postby stew79 » Sun Nov 12, 2017 3:09 pm

if you turn the engine backwards (presumably with the plug out) and it sparks, is it when the points open, or close ? the timing of the points is very important, not only were in relation to tdc but on what cycle of the engine (not just before tdc on exhaust stroke by mistake) if it is the et system, the max amount of adv / ret available is only 10 crank shaft deg (make that 8 deg for a small margin error) so if you have the wrong adv / ret unit on the cam, your initial set up point may be out side the range of where the power pulse from the alternator is. then there is the coil to think about, the et has a specific one that is different to the points / battery one. it goes on and on, but in tip top condition the system is hardly suited to a big single anyway. fit electronic ?
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Re: Repolarisation of Magneto/ Stator- Rotor?

Postby beat » Sun Nov 12, 2017 4:27 pm

good point stew,
the atu is different by the et ignition.
can not remember me what degrees, but it was never the 15° as it is common on the B50.

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Re: Repolarisation of Magneto/ Stator- Rotor?

Postby skippy » Sun Nov 12, 2017 10:14 pm

Magnetos are designed to give maximum spark at zero advance, that is just as the magnet leaves the coil the points open.
The faster the magnet goes the greater the energy produced so you can advance the points opening to advance the timing and get away with still having a spark. A magneto will work backwards by altering where the points open, so that it opens when the magnet leaves the coil in the opposite direction.
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Re: Repolarisation of Magneto/ Stator- Rotor?

Postby midgie » Sun Nov 12, 2017 11:16 pm

beat wrote:good point stew,
the atu is different by the et ignition.
can not remember me what degrees, but it was never the 15° as it is common on the B50.

beat <017

The Et system used a 5 degree atd beat.

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Re: Repolarisation of Magneto/ Stator- Rotor?

Postby beat » Mon Nov 13, 2017 8:44 pm

midgie wrote:The Et system used a 5 degree atd beat.

thanks midgie,- so if bikestyles is using a 10° or a 15° one it won't work?
is it right ?

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Re: Repolarisation of Magneto/ Stator- Rotor?

Postby skippy » Mon Nov 13, 2017 10:29 pm

beat wrote:
midgie wrote:The Et system used a 5 degree atd beat.

thanks midgie,- so if bikestyles is using a 10° or a 15° one it won't work?
is it right ?

beat <201

It would start but would run out of spark as it advances, as long as the starting degrees was the same as the 5deg unit.
If it was set at maximum advance then i would say it wouldn't start unless it was spun at high speed.
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Re: Repolarisation of Magneto/ Stator- Rotor?

Postby bikestyles » Tue Nov 14, 2017 9:37 am

Good morning

I managed to "turn" the spark yesterday but need to doublecheck before posting more. :idea:

When I started Saturday I had all positioned as on the pictures at tdc.... so I have to get into it again for being 100 sure what was the solution really. <201

Cheers from Berlin
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Re: Repolarisation of Magneto/ Stator- Rotor?

Postby stew79 » Tue Nov 14, 2017 9:43 am

well put skippy, but how to ex plane the "it only sparks when run backwards" bit ? :werd also that looks like the normal coil ? bikestyles, what is the primary resistance of it ? if its not 0.5 ohm that wont help
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Re: Repolarisation of Magneto/ Stator- Rotor?

Postby bikestyles » Tue Nov 14, 2017 10:14 am

Hi Stew

I do not know as my proper electric stuff went to???? I have tested it with a Bosch coil as well with no difference.

Saturday I checked different points positions as well without any solution.

So it seems still <004 <004 <004 <004 .

I let you know tonight cause I need a third hand to flash the timing. I simply cannot turn the engine with a cordless driller and look at the strobo.

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Re: Repolarisation of Magneto/ Stator- Rotor?

Postby minetymenace » Tue Nov 14, 2017 11:29 am

The advance should be marked on the plate behind the bob-weights...either way do you get a spark if you static time with NO advance?
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Re: Repolarisation of Magneto/ Stator- Rotor?

Postby stew79 » Tue Nov 14, 2017 11:47 am

hi bikestyes, you seem to be doing this all wrong, and wonder why it dosent work !. timing must be set to the correct position from the book (not moved about a bit ??) all the ignition components must be of the right type (not the mixture you have) then it will run, then to be strobed with a degree wheel and suitable pointer to cheque the advance/ retard is working correctly. from there on you can adjust things to perhaps improve how it runs. but looking at what you have it may be normal battery points ignition, the battery could have been replaced with a large capacitor, but thats missing ? (not et ignition) a bosch coil could have any number of different resistances depending on what is for, so no good for a comparison (with out a multi meter to cheque it)
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Re: Repolarisation of Magneto/ Stator- Rotor?

Postby midgie » Tue Nov 14, 2017 3:52 pm

From the picture, it looks like the points wire terminal is touching the timing cover.

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Re: Repolarisation of Magneto/ Stator- Rotor?

Postby beat » Tue Nov 14, 2017 7:22 pm

and I do ask me: the cable from the stator: should it not pointing to the inner of the engine ??
at least on mine it dos....

<017 <017 <017

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Re: Repolarisation of Magneto/ Stator- Rotor?

Postby midgie » Tue Nov 14, 2017 8:28 pm

beat wrote:and I do ask me: the cable from the stator: should it not pointing to the inner of the engine ??
at least on mine it dos....

<017 <017 <017

beat

Yes beat I would say the stator is arse about face.

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Re: Repolarisation of Magneto/ Stator- Rotor?

Postby bikestyles » Tue Nov 14, 2017 8:45 pm

Hello and thanks for the hints:

First: All parts were used from me on another B50 but were on a shelf for a decade. THOSE Days they were working. :ban

Second: There is no cable wrong connected or touches another one or even ground. :ok

Third: As I wrote Saturday, I changed all positions of stator and rotor. It did not matter where its arse was, nor the arse of the rotor, or the arse of the condenser, or mine :laugh - it fired still the wrong way.

Fourth: I put a batterie charger on the plus and minus of the stator and finally it repolarized it. THAN it started sparking the right way. And it sparks even when the points are way out of timing. But now the spark is more and more weakish and I think the condenser fades away. I have ordered a new one and
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Re: Repolarisation of Magneto/ Stator- Rotor?

Postby skippy » Tue Nov 14, 2017 11:30 pm

bikestyles wrote:Fourth: I put a batterie charger on the plus and minus of the stator and finally it repolarized it. THAN it started sparking the right way. And it sparks even when the points are way out of timing. But now the spark is more and more weakish and I think the condenser fades away. I have ordered a new one and

That would suggest the stator had become magnetized and you demagnetized it and if the spark gets weaker it maybe getting magnetized again. check it with some iron to see if there is any magnetism in the stator.
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Re: Repolarisation of Magneto/ Stator- Rotor?

Postby bikestyles » Wed Nov 15, 2017 6:18 am

Thanks Skippy

I thought this as well and put the magneto off and a batterie on. Spark was not any stronger on the plugside but I had a strong spark at the points..

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Re: Repolarisation of Magneto/ Stator- Rotor?

Postby hwan » Sun Nov 26, 2017 6:49 pm

Maybe unrelated but, while looking through some official LUCAS data, for something else i came across an interesting comment;

"If the stator is energized (faulty rectifier, etc.) and the rotor is turned, it can DEMAGNETISE the rotor"

Now, I'm not certain how a standard wiring system can cause a stator to be energised by the bikes battery(Lucas suggest a faulty rectifier) - but as a rotor is magnetised by placing it into a strong electromagnet field surrounding the rotor - its easy to see how the same process, if the stator is connected the 'right' (wrong way really) way round to reverse the gaussing polarity, can de-magnetise the rotor.

Never really thought about this before, but if unconnected stator outputs are connected to earth while the engine is running - could it 'self generate' and deguass the rotor ???

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Re: Repolarisation of Magneto/ Stator- Rotor?

Postby minetymenace » Sun Nov 26, 2017 7:34 pm

The only way you can magnetise the stator is to place it in the vicinity of a strong magnetic field. If the rectifier was short circuit, it would be possible for the stator to be energised by the current flowing through the faulty rectifier and then through the coil of the stator. IMHO to magnetise the stator you would have to have a somewhat bigger field strength/coil/battery than those on our bikes and you would need to have replaced the fuse with a fat copper link to get anything like the required current to flow. It has equal chance of rejuvenating the stator or doing nothing at all, it just depends on the position of the rotor when the engine stops (and stop it will). It is also not possible if no battery. The chances of this happening in the real world are practically zero.

hwan wrote:Never really thought about this before, but if unconnected stator outputs are connected to earth while the engine is running - could it 'self generate' and deguass the rotor ??


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Re: Repolarisation of Magneto/ Stator- Rotor?

Postby stew79 » Sun Nov 26, 2017 9:16 pm

i must agree with minety, the rotor magnetism aint going to change. (not even the 1/3 that the stator actually covers) while experimenting with my electronic starter conversion, i re wound several full cover stators (one and three phase) with many combinations of coils, wire thickness, number of turns etc, drawing up to 20 amps (from 12 volt 3 phase) even that amount of magnetism has no effect on the rotor. when a rotor is made, and finally magnetized, it is probably with several hundred amps, with coils of 3 or 4 turns of 6mm or more diameter wire. the less than 1mm wire in the 1/3 stator is not going to change anything
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Re: Repolarisation of Magneto/ Stator- Rotor?

Postby Barry Creary » Sun Nov 26, 2017 9:44 pm

How is your starter experiment going Stew79 beats getting on with his very nicely <216 <214
Thank you Minety
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Re: Repolarisation of Magneto/ Stator- Rotor?

Postby stew79 » Mon Nov 27, 2017 10:20 am

hi barry, a bad generator makes a bad motor, so the plan to use the std 9 pole stator isnt efficient enough to work well, even with re wound coils. the best option is for a new 27 pole stator in modern silicon iron, with distributed windings. other work, and a possible house move, have put this on the back burner.
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Re: Repolarisation of Magneto/ Stator- Rotor?

Postby JB » Mon Nov 27, 2017 10:34 am

bikestyles wrote:Thanks Skippy

Spark was not any stronger on the plugside but I had a strong spark at the points..

S.

Looking at your pictures, is that the condenser next to your ignition coil? If it is then it physically appears way too big.

if your condenser is too big it will be taking too much energy to charge it and it will throw out the ignition, especially so on such a finely balanced one as an energy transfer system, might even explain why it appears to work in reverse?

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Re: Repolarisation of Magneto/ Stator- Rotor?

Postby beat » Mon Nov 27, 2017 7:02 pm

JB wrote: is that the condenser next to your ignition coil? If it is then it physically appears way too big.


the capacity of the condenser should be around 0.2uF. ( 0.15 - 0.3 uF )

watch out for proper connection ( electricaly ) to the ground on it :!:

not sure there was something especially used on the ET system....?

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Re: Repolarisation of Magneto/ Stator- Rotor?

Postby hwan » Sat Dec 02, 2017 9:01 pm

Stew & Minty -

My comments about De-magnetising a rotor are from a LUCAS publication, not something i thought up myself - specifically regarding the LUCAS Alternator fitted to the typical Britbike.
If i can be arsed, i'll work out how to publish the work-sheet for you all to peruse.

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Re: Repolarisation of Magneto/ Stator- Rotor?

Postby stew79 » Sun Dec 03, 2017 11:07 am

thanks hwan, that would be interesting to read. in the past i have tried to reduce the magnetism of two different bikes rotors. (for running home made ignition, and less powerful lights etc with less drag / heat) on both occasions i failed to make any significant difference. i event took advice from a cambridge magnetic research company. the Japaneses magnets in question may have been made from better / different stuff to lucas ?
stew


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