Do I have an ignition problem

[Fastmongrel]

Oh flipping flip the problem has reoccurred bike was running like a dream until coming home from a blast round north Wales halfway through the Mersey tunnel bike started to hesitate I nursed it until I was near home and it stalled at a traffic light. Now won't start

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Ignition winding burnt out after 340 miles. I spoke to Sharon at West country windings and it's on its way back to them for a test there must be an underlying issue I can only think the permanent magnets are weak

[lemans]

well if the permanent magnets are weak then the winding can't have been burnt. so there must be a short somewhere in or near the winding

[Fastmongrel]

I am going through the wires looking for anything out of the ordinary. So far I have replaced the main fuse holder as it looked a bit corroded.

[mbmm350s]

Hi Fastmongrel

I don't really know what to say, I am truly sad for you that West Country windings couldn't rewind the coil the same as the original
The generator winding is  supposed to be a tall  bobbin, not a short bobbin.
I reckon this has been wound with the wrong gauge of wire = far too small = too high resistance = too much loss = too much heat = burnt out
Where is the overvoltage rivetted keeper plate gone? I can see the rivet holes? but no metal plate
If there were a short of your green wire the ignition would be killed this is how the ignition kill switch works already.

This will need to be returned for rectification.
The bobbin is not to be wound like a scooter - which has typically 470 to 500 ohms but only has 1 CDI and usually lives below 6000 rpm
A full height bobbin should be wound with as many turns of 0.15mm class H wire*  that can be fitted this will not in my experience and corroborated by others experience reach 300 ohms, more likely 260-270 ohms at room temperature The number of turns is around 3000
https://www.morini-riders-club.com/foru ... 815?t=3815

I advise the return of the overvoltage keeper as this helps to protect the transducers from overvoltage (spike) damage

* I used to design power supplies, ignitors etc for military uses, but it was a few years ago and standards do change , the temperature rating for the Morini coil needs to be at least 180c, but that will be the class commonly in use for motorcycle engine mounted components and any reputable company would have that in stock and not wire used for jewelrey etc.

Mark

[Fastmongrel]

"Where is the overvoltage rivetted keeper plate gone? I can see the rivet holes? but no metal plate"

Erm I don't know......wots one of them

[Fastmongrel]

Currently working through the wires pulling all connections apart and checking for corrosion and resistance. Cleaning with meths and 1200 grit wet and dry.

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[Steve Brown]

The plate Mark refers to above is a right angled piece of metal that look like a bracket to us uneducated types. It works by magic to stop the voltage produced by that coil. Yours is missing and as you said earlier your new coil was 470 ohms! So it was always likely to cause trouble and burn out either itself or the CDI (transducers)
Last time I had a faulty coil on the stator I bought a new coil for a scooter online that was 200 odd ohms. That is still working years later. I can't remember if it was meant for a Lambretta or a Vespa but it was cheap and readily available. Fitting it required dexterity and nimble fingers that I don't have, so it did make me sweat a bit but I succeeded! I think the coils were branded 'Swiss' but manufactured in India.

[Fastmongrel]

I have been through every single wire and connector cleaning and checking resistance and continuity. Overall the wiring is pretty good for a 43 years old bike only the main fuse holder, the earth point on left hand side of head stock brace and the wires to the horn had any significant corrosion. All sorted and clean I reckon the wiring is as good as the day it left the factory.

Just waiting for the stator to come back from West country windings and I hope I am sorted.

[Fastmongrel]

Well here we are again back to square one

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Low tension ignition coil has burnt out again after less than 200 miles. I have emailed West country windings but there must be an underlying issue. Has anyone got any ideas for what to check next.

While the coil is okay the bike runs a treat starts first spin and revs smoothly all the way to the red line. I have checked all the wiring and all the earthing points every thing has very low resistance around 0.2 ohms. Can't see any kinked or squashed wires.

[72degrees]

"When I tested resistance it was 129ohms it's now 470ohms well over the 300ohms specification."

I think Mark may be correct in diagnosing that the resistance is too high (assuming West Country Windings have rewound it in a similar way).

Perhaps 'resistive heat' is just cooking the winding?

[Fastmongrel]

"When I tested resistance it was 129ohms it's now 470ohms well over the 300ohms specification."

I think Mark may be correct in diagnosing that the resistance is too high (assuming West Country Windings have rewound it in a similar way).

Perhaps 'resistive heat' is just cooking the winding?

That's what I guessed must be happening the winding must be acting like an electric toaster. I don't know the melting temperature of the wire insulation is but I am guessing it must be north of 100°C.

It's really frustrating I have missed a lot of good riding weather and now looking like I will miss the rest of September. Beginning to lose the love for this bike and I have started looking at Japanese twins.

[72degrees]

Might be better to try to find a "known good" stator. Not easy, as those that have them on the shelf in a shed are probably hanging on to them.

Just possible I have one I don't need, will search and test.

[MickeyMoto]

Is there any DC voltage on the coil with the ignition off or on?

[Ian_C]

Hi Fastmongrel
I would suspect that there is a rogue DC supply superimposed on the green wire when the ignition is switched on, try putting a multimeter in series with the green wire and checking for a DC current, ignition on but without the engine running. Ian C

[Fastmongrel]

Hi Fastmongrel
I would suspect that there is a rogue DC supply superimposed on the green wire when the ignition is switched on, try putting a multimeter in series with the green wire and checking for a DC current, ignition on but without the engine running. Ian C

Do I disconnect the green wire from the junction box and connect one meter probe to green and one probe to earth to test for a DC supply. Or do I put the meter between the green and the junction box green connection.

Sorry for sounding dumb I can rebuild a gearbox but electrical problems just make my head spin.