1979 Moto Morini 125H ignition problems.

[themoudie]

Rather than continuing to post in the "Veglia revcounter bracket " thread and to keep some sort of order, I hope that this separate thread is acceptable? If not please delete and advise. Thank you.

17/1/2023 themoudie
"My current "Bete noir!" is the Moto Morini 125H ignition problem. This is the same problem as that discussed, with you, by a man named Leonard, before Xmas. Both of us have been driven to distraction by the failure of the flywheel to cause the trigger coil to advance the ignition spark and nobody from the UK MRC, MMOC Netherland, or ignition/electrickery world has been able to come up with a solution. I'm considering a small Ducati engine or alternative could be made to fit. Or, maybe even a stink wheel!
THIS DOES NOT REQUIRE YOUR DIVERSION. "

17/1/2023 Jordan
"The pickup on Morini uses an inductive coil I think.
As the induced waveform may not be symmetrical, try swapping the two wires."

17/1/2023 themoudie
"Aye Jordan,
Thank you for your suggestion.
Without going into detail the 125H uses a Lambretta/Vespa type flywheel ignition, within the generator rotor. Yes, the trigger coil is inductive and is supposed to produce a full waveform. This was part of my problem, because mine didn't produce a full wave form and therefore didn't advance the ignition. However, since replacing the trigger coil and using 3 different trigger coils, there is no ignition advance. All of the other components have been passively and dynamically tested and appear to be functioning correctly. So, it appears that the interaction, or lack of it, between the generator rotor and trigger coil appears to be the problem. Ducati Electronnica components greater than 30 years old appear to be the problem and OME replacements are no longer available. At present there are no alternative ignition systems manufactured to replace the OME and having contacted all potential manufacturers and received polite "Not worth the time and effort.", my thoughts are turning to alternative engines!
If your interested in the saga so far, here is the link to the thread on the Morini Riders Club forum: MRC_MM125H_ignition_no_spark!"

18/1/2023 Jordan
"I've noticed on my trusty oscilloscope that trigger coils usually produce a sine type wave, but with the slope on one side being very steep (near vertical), the other a gentle slope. Vertical waves usually don't show up on the display, although they are part of a full waveform.
The gentle slope's steepness increases with rotor speed, and this is how the CDI advances, as the trigger voltage arrives earlier in the cycle.
With wires improperly crossed, the gentle slope is not active, but steep slope is, but it cannot provide the needed variation related to engine speed - so ignition is virtually fixed.
Easy to try changing over the wires.
I'm not saying that's definitely the cause of your woes as some internal CDI circuitry might be faulty."

Bill

[themoudie]

Aye Jordan,

Because the induction/trigger coil only has a single wire and is fitted to the stator, inside the rotor, I am not clear how to "swap the wires"? This advice has been proferred by many and would work if the engine was a 250 single, or 250/350/500 v-twin, as their trigger coils are mounted at the end of the camshaft on the left-hand side of the engine and triggered by the camshaft. Whereas, the 125H alone has 4 charging coils mounted on a stator, plus a low tension coil to power the CDI/HT unit and the trigger/induction coil mounted on the other two poles of the stator. The ignition timing being controlled by two shaped prongs on the inside of the rotor using a magnetic flux, I think.

I have attached images for clarity.

My thoughts were to use a 250/350/500 left-hand side cover and take the timing from the end of the camshaft. Nigel Lacey has written to me, suggesting the same solution, so I am not thinking "pink elephants"! However, due to other jobs and the current temperatures, I haven't drained the oil and stripped out the 125H's left-hand casing, yet. Confidence, loon!

I think it best to keep this thread separate from the panel beating Veglia bracket.

Thank you for your thoughts and good health, Bill

[Jordan]

In case it's of use, I found some Indian made CDI ignition components to be interchangeable with those on Ducati singles.
It seems they made Vespas and Lambrettas under licence, including the electrics, which are evidently Ducati design.
I think Morini also used Ducati-sourced ignitions.
Except for the pickup assembly, the ignition system on my Ducati 350 is all made in India.

[themoudie]

Aye Jordan,

I have used components from Indian suppliers via scooter spares suppliers in the UK. One of the trigger coils was found to be faulty! This is also another potential problem, as the trigger coils were wound specifically to match the CDI/HT modules and provide the required amount of ignition advance. Whether the "replacement" trigger coils, including supposed OME stock have the same number of windings on the encapsulated iron cores, is questionable.

Hence, my seeking possible alternative solutions.

Thank you for your time and advice.

Good health, Bill

[Duccout]

Bill,

Have you tried people like AO Services or Rex's Speed Shop to see if they can modify another type of ignition to fit the Morini? I know that Mistral Engineering used to do one-off mods when they were in business.


Cheers,

Colin

[themoudie]

Aye Colin,

Thank you for your suggestions.

I was in correspondence with AO Services and Al Osborn was as brusque as his reputation that goes before him. But, he was very helpful, although unwilling to involve himself with it, as he had plenty of Classic British work to do.

I was in conversation with Rex's Speed Shop as well and despatched the complete system to them, at the end of COVID lockdown. I understood that it might take some time to assess and was advised that I would hear from them within 6 to 8 weeks. 12 weeks later I asked if any progress had been made. I was told that due to a lack of experienced staff, they were unable to test and repair the ignition and that it would be returned to me. A further week passed and all the components, less the generator rotor, arrived home having been through the Royal Mail milling machine. I rang the workshop and after prefuse apologise, the rotor was located whilst I was still on the phone and as promised returned to me by 'SignedFor' post.

Boyer, Electrex, Sachs and many others have all been approached either by myself or Leonard (MRC) and they have either told us that they are unable to offer an alternative "ready to fit" system, or are not willing to exmine the system. We have also sent the systems off to other bonafide motorcycle/scooter electrical repairers, who have tested all the components individually and as a complete system on test rigs up to 10,000 - 20,000rpm and with no ignition advance observed?

For me the time has come for modification. Whilst, Leonard has located another rotor on the Continent, that he was assured was creating the necessary advance and was receiving it on loan to test on his engine. I have not heard of any developments, to date. I suspect that something might happen once the weather improves.

Good health, Bill

[Duccout]

Jeez Bill,

No wonder you are looking at fitting another engine! This really does illustrate the problem with modern machines when spares are not available and they were produced in small numbers. What about the bigger Morinis, do they have the same ignition woes?


Cheers,

Colin.

[Jordan]

Bill said:
I have used components from Indian suppliers via scooter spares suppliers in the UK. One of the trigger coils was found to be faulty! This is also another potential problem, as the trigger coils were wound specifically to match the CDI/HT modules and provide the required amount of ignition advance. Whether the "replacement" trigger coils, including supposed OME stock have the same number of windings on the encapsulated iron cores, is questionable.

Hi Bill,
Indian parts can be faulty as new, but they are not expensive. I had a CDI/coil unit die on me after a couple of months, but its replacement has been going well for years now. This situation works for me, as new original electrical parts for Italian bikes are hard to find, can be very expensive, and not famous for reliability.
I think many folks worry too much about getting a theoretically perfectly correct ignition advance curve. As I have owned bikes with manually-controlled advance, I came to learn that approximate accuracy is satisfactory. The main thing is to have enough retard for easy starting, and of course full advance timing is up to the installer.