125 WITH NO SPARK

Lambertini era singles (125 and 250 - half v-twins)
mbmm350s
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Re: 125 WITH NO SPARK

Post by mbmm350s »

Hi Bill

I think you are in danger of overthinking this, slacken the stator screws which since its a scooter you can do in situ
move the stator clockwise 12 degrees relative to the rotor (so trigger is later), you can make some marks on the rotor to help, 36 degrees is the distance from ANT to PMS, so as Ming says 1/3 of that is how much the stator needs to move.
That could be quite a lot - not sure if the slots in the stator plate can go that far, I suggest go as far as you can and try there first.

No new permanent marks on the rotor needed. You will make a new mark on the stator and a corresponding mark on the crankcase if there isn't one handy for alignment should you ever remove the stator eg for belt replacement, its arbitary where you make the marks, so long as you know to align them after belt replacement.

Likely a standard rotor fitted to probably thousands of small Italian motorcycles. The stator is more than likely the same design as a Vespa with a 100 ohm magnetic pickup but made to fit Moto Morini crankcases.
The rotor has no effect on ignition timing.

32398 112 21 02 ignore the last four digits they are a YY MM date code.

The advance range when running is more or less the same for the blue transducers as the black ones, perhaps a little less.
cheers
Mark
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themoudie
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Re: 125 WITH NO SPARK

Post by themoudie »

Aye Mark,

Thank you for the clarification "move the stator clockwise 12 degrees relative to the rotor (so trigger is later)", in my head that makes sense! :roll:

Now to implement it. :wink:

Good health, Bill
mbmm350s
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Re: 125 WITH NO SPARK

Post by mbmm350s »

Good luck Bill,

The rotor has no effect on ignition timing.
Of course the shape of the magnets (or notch) and the rotor to pickup clearance do of course affect ignition timing, but the primary method of adjusting timing is the location of the pickup.

Cheers
Mark
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themoudie
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Re: 125 WITH NO SPARK

Post by themoudie »

Aye Mark,

Now, after an afternoon and evening of testing, I am even more confused! :roll:

I fixed a piece of masking tape on the rotor circumference and marked up the PMS and ANT marks along with a revised ANT2 that is two thirds of the circumferential difference between PMS and ANT, to the right of the PMS mark.

Limited by the length of the stator fixing bolt slots, I could retard the ignition by ~7° from the original factory timing mark on the stator (fully clockwise). Advancing the ignition by ~5° from the original factory timing mark on the stator (fully anti-clockwise) is also possible. Any further extension of the timing range will require the stator slots to be elongated and is likely to result in one of the slots becoming open ended!
Once the position of the pickup is confirmed the loss of power beyond a certain RPM can be due to insulation breakdown (voltage induced) or partial collapse of the magnetic field, this could be caused by short circuit caused by faulty regulator in the lighting circuit, so I would disconnect the battery to be sure.
With the stator plate retarded as far as possible (clockwise from factory timing marks) and the battery connected, the engine started and settled to a steady 1,100 rpm tickover. However, when the throttle was opened the revs climbed then quickly cut-out. Next I disconnected the battery earth and restarted the engine that settled to a steady tickover. As the revs were increased the engine stumbled badly and then died. The PMS mark illuminated by the in-line neon strobe, remained ~5° to the right of the camshaft axis throughout the two tests.

The stator plate was then moved to the factory timing marks and the same tests performed. The tickover was a steady ~1,200rpm. With the battery connected the revs climbed and then stumbled and cut out at ~4,500rpm. Again the battery earth was disconnected and restarted, the engine settled to a steady tickover. But, again as the revs climbed toward ~4,500rpm the engine stumbled and cut out. Throughout both of these tests the strobed PMS mark appeared to remain approximately in line with the camshaft axis, with no lateral movement.

Finally, the stator plate was moved to the maximum advance possible and the same tests performed. Again the engine readily started and settled to a steady ~1,200rpm tickover. With the battery connected the revs climbed and then stumbled and cut out at ~4,500rpm. there was a slight clockwise movement of the PMS mark as the revs increased, but not sufficient, in my opinion, to indicate that the transducer advance was operating. I then disconnected the battery earth and re-started the engine, which settled to a steady tickover, as before. I then opened the throttle and the revs climbed strongly. to a point where the PMS mark no longer appeared in the strobe light to align with the camshaft axis, neither did ANT or ANT2 align with the camshaft axis. The revs were sustained for a much longer time and the top 30cm of the exhaust pipe was glowing cherry red after approximately 30 seconds and the engine then stumbled and cut out.

The rotor was too hot to touch after this last run. The difference between making the tests with and without the battery earth connected could be significant. But earlier tests on the charging system didn't show any problems with that side of the system, so I am inclined to a "voltage induced insulation breakdown" or "partial collapse of the magnetic field" or both! :evil:

I would be delighted if "andygrew" the originator of this thread would let us know if he made any timing adjustments to his 125H, after fitting his Vespa ET125 transducer, as recommended by Steve Brown.

First "to do", will be to replace the low-tension coil on the stator (if my soldering skills are up to it!).

As for the timing conundrum, I'm baffled and suspect that until the low-tension coil is functioning correctly, it will remain a conundrum. Ruddy Italian electrics, yet again! :twisted:

Thank you for your time and advice, Bill
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Re: 125 WITH NO SPARK

Post by EVguru »

The only thought that occurs, is that the charging coils could be shorted and resulting in the stator iron becomming magnetically saturated. This might prevent the ignition coil from producing enough voltage for the CDi module.
Paul Compton
http://www.morini-mania.co.uk
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themoudie
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Re: 125 WITH NO SPARK

Post by themoudie »

Aye Paul, thank you for offering another scenario. However, when carrying out the tests from the Blue book and others suggested by Mark, there was no indication of any problems/shorts with the charging coils, rectifier/regulator, or between the ignition/lighting circuits through the ignition switch. These included voltage, amperage and resistance tests.

Trying to sort out the change in ignition timing required by using the different transducer, whilst having a dodgy low tension coil/magnetic pick-up coil has proved a waste of time.

I have drained the fuel out of the tank/carb and fuel lines and stripped the stator off the crankcase. There is part of me that would have a crack at stripping the low tension coil off the stator, mounting a new coil and soldering everything back in place. But there is also part of me that is inclined to send it off to Rex' Speed Shop. However, the only way that I am going to be able to get near the further 12° retard of the ignition that the new transducer requires, is by extending the mounting slots and this will require the upper right mounting slot to become an open ended slot and some accurate machining. Morini 125H alternator stators are a bit like rocking horse dung, so extending the mounting slots afore changing the coil's and wiring seems the best way to go.

Somebody, will probably tell me that there is no need to change the ignition timing now! :roll:

Thank goodness it only has one cylinder and no ECU! :wink:

Good health, Bill
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Re: 125 WITH NO SPARK

Post by EVguru »

The timing issue can be solved with external resistors. The CDI modules just fire at a fixed trigger voltage. The advance curve is created by the interaction of that trigger voltage with the amplitude of the waveform from the pickup.

The cutting out problem is the one that needs to be solved first.

I suspected magnetic saturation because you mentioned the flywheel getting hot. It could though be a vibration related loss of connection.

Try measuring the ignition winding voltage whilst the engine is running. It should rise lenearly with rpm and then plateau at somewhere around 300VAC. That is a magnetic saturation effect caused by the copper plate retaining the igntion winding, which prevents the voltage exceeding the rating of the components in the CDI module. Any sudden drops in voltage suggest an intermittent connection.
Paul Compton
http://www.morini-mania.co.uk
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themoudie
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Re: 125 WITH NO SPARK

Post by themoudie »

Thank you Paul for your quick response.

I note the test that you suggest for "magnetic saturation", as the rotor was very hot after the less than a minute of running last night. Initially when running on the road and trying to diagnose the problem, a misfire and blubbering of the engine could almost be predicted after 5 miles running. However, on more than one occasion after letting the engine cool, I was able to travel a further 15 - 20 miles with no further problem! :roll:

As for adjusting the ignition advance using resistors that is "smoke and mirrors" to me and I would be interested to learn more, in VERY layman's terms! The physics and reasons behind electrical interactions are, I find, difficult to visualise/comprehend. I scraped an 'O' level Pass in physics.

I have also been reading the thread on the German Moto Morini Forum from 2013. Andre, who instigated the thread found that the replacement transducer #32398 112 performed well with the Red magnetic trigger coil. Whilst it would also work with the black magnetic trigger coil, if a diode integrated in the red trigger coil is included in the pickup cable. I renewed my black trigger coil, with another black trigger coil. Should I order a red trigger coil and include that in a rebuild?

This is the thread entry where Andre describes his setup, translated from the German using 'Google Translate' :-
Hi there,
to the blue Vespa ignition coils:
I have now flashed off the ignition and have come to the conclusion that these blue ignition boxes go wonderfully with the red pickup. The ignition timing was initially too early when I set the pickup according to the housing markings. But the correct setting was still possible within the elongated holes of the pickup, albeit very far in the direction of the retarded ignition. The advance adjustment also works very well, so I can only recommend this ignition box for the red pickup.

In practice this means that the box can also be used for the black pickup if the corresponding diode, which is integrated in the red pickup, is built into the cable from the pickup.
But that's something for the "Strega" soon.
greeting
andre
Link to the thread on the German Moto Morini Forum: Replacement_Blue_Transducer

I shall rebuild the alternator onto the engine, give your saturation test a try and report back on the result.

Thank you for your time, Bill
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Ming
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Re: 125 WITH NO SPARK

Post by Ming »

Following on Paul’s comment about resistors, if you look on the Dutch site there is a circuit for the transducer, which shows alternative resistor values to change timing for the 350 and 500. I think Paul's suggestion is to add a resistor in series with the pickup input. Agree that the rotor heating problem needs sorting though.
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themoudie
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Re: 125 WITH NO SPARK

Post by themoudie »

Thank you Ming for giving me the information of where to look for the resistor values. I am not sure if my soldering skills are up to the job of replacing the low tension coil, or whether my Gunson meter is up to the job of making the relevant tests once I replace the coil.

I will post updates on this thread and the end result!

Good health, Bill
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Re: 125 WITH NO SPARK

Post by MickeyMoto »

themoudie wrote: 18 Sep 2021 22:39
I note the test that you suggest for "magnetic saturation", as the rotor was very hot after the less than a minute of running last night. Initially when running on the road and trying to diagnose the problem, a misfire and blubbering of the engine could almost be predicted after 5 miles running. However, on more than one occasion after letting the engine cool, I was able to travel a further 15 - 20 miles with no further problem! :roll:
I had the clutch casing off the 350 two weeks ago. I put it together, set the static timing and had trouble starting the thing. Once started I did a timing check and it was well retarded. The engine got hot very quickly at 6k rpm! At tickover it was not happy, popping and farting like a deaf pensioner. After more messing, I got the timing near and the engine ran cooler and the tickover increased. It ran a lot crisper, obviously burning what we laughingly call fuel more efficiently. The rotor will get hot, the engine will get hot on the stand without an airflow.

Just my observation.
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themoudie
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Re: 125 WITH NO SPARK

Post by themoudie »

Aye Micky, thank you for your additional comments, it all helps.

I have never had a problem acheiving a steady tickover @~1,100rpm. The problem has always been either a reluctance to rev, or once revving a sudden lack of power or the engine cuts out completely and then refuses to start unless left to cool. Once re-started, it will sit and tickover quite happily, but maybe unable to produce enough power to move off under load, or takes off and runs for a further 15 - 20 miles at speeds up to 50mph, with no untoward popping, banging or blubbering. :twisted: As for the deaf pensioner scenario, I thought that was quite "normal"! No, I'm no deaf! :roll: :lol:

Been on the hill all today, so not cluttered my head with it and will do a bit more research into the difference between black and red magnetic trigger coils, with the use of a resistor in the low tension coil feed to the transducer.

Good health, Bill
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Re: 125 WITH NO SPARK

Post by MickeyMoto »

themoudie wrote: 20 Sep 2021 22:50 Aye Micky, thank you for your additional comments, it all helps.

I have never had a problem acheiving a steady tickover @~1,100rpm. The problem has always been either a reluctance to rev, or once revving a sudden lack of power or the engine cuts out completely and then refuses to start unless left to cool. Once re-started, it will sit and tickover quite happily, but maybe unable to produce enough power to move off under load, or takes off and runs for a further 15 - 20 miles at speeds up to 50mph, with no untoward popping, banging or blubbering. :twisted:

I had a Kanguro that did the same. Until, one day, it stopped at a junction and would not restart. The magneto coil had finally broken down. The low loader of shame had to be called.

As for the deaf pensioner scenario, I thought that was quite "normal"! No, I'm no deaf! :roll: :lol:

Thought it was just me!

Good health, Bill
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themoudie
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Re: 125 WITH NO SPARK

Post by themoudie »

Good morning Mickey,
I had a Kanguro that did the same. Until, one day, it stopped at a junction and would not restart. The magneto coil had finally broken down. The low loader of shame had to be called.
So, did you replace the coil yourself or did you send the stator away to have somebody else do the job? If so, who did you send it too?

Thank you for your help.

Bill
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Re: 125 WITH NO SPARK

Post by MickeyMoto »

Mornin' Bill,

Try West Country Windings in Essex, innit. They will also check the alternor windings but won't rewind them.

Mike.
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