Do I have an ignition problem

[Fastmongrel]

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.

Thanks I but I would like to eliminate all possible faults before I try another stator. I wouldn't want to cook another coil they seem to be rarer than rocking horse poo

[MickeyMoto]

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

The reason I ask is that you have replaced and moved the ignition switch.

https://www.morini-riders-club.com/foru ... 711#p41711

I would start here. The green wire at the ignition switch is shorted to earth when the switch is off or in park. It becomes open circuit with ignition on. See Ian's post, but I would put the volt meter between the green wire terminal and earth. Only disconnect the green wire from the transducers at the junction box, measure with the other wires still connected. Look for voltage with ignition switch on and off. I suspect the switch is ok when off, as the engine stops, unless you use the kill switch. Ensure this is on run, ie open circuit, when looking for volts.

Good luck.

[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.

Thanks I but I would like to eliminate all possible faults before I try another stator. I wouldn't want to cook another coil they seem to be rarer than rocking horse poo

Indeed.

The killed by a 12v input scenario is well worth investigating.
I have had problems with the ignition switch on my 2C (just a four terminal one on a '250'). The switch was inclined to turn with the key and lead to spade connections popping off. Usually resulting in just dead ignition as the failsafe shorting out mode is fairly fool proof. Well insulated female spade terminals but a short circuit from the 12v supply in that area couldn't be ruled out.

Magic smoke issues can be tricky to diagnose - particularly if intermittent, but methodical use of a tester as MickeyMoto and Ian_C advise should confirm or deny.

[morini_tom]

When your last stator burnt out, Mark asked where the riveted on keeper plate had gone.

I can’t really see in your most recent photo but it’s not obvious that that fault has been rectified. Can you post a few more pictures of that area?

[Fastmongrel]

When your last stator burnt out, Mark asked where the riveted on keeper plate had gone.

I can’t really see in your most recent photo but it’s not obvious that that fault has been rectified. Can you post a few more pictures of that area?

The plate is missing

[Fastmongrel]

1. Meter set to DC voltage probe to green wire from stator and probe to cylinder head to earth. Ignition on
0.021 volts

Compress_20230923_094123_3721.jpg (203.51 KiB) Viewed 2565 times

2. Meter as above ignition off
0.000 volts

Compress_20230923_094122_2530.jpg (321.45 KiB) Viewed 2565 times

3. Meter connected to green wire and green connector in junction box ignition on
0.003 volts

Compress_20230923_094124_4676.jpg (157.48 KiB) Viewed 2565 times

[mbmm350s]

West country windings have most likely replaced your original bobbin with a scooter bobbin. VESPA stators look very similar to Morini stators so an easy mistake to make.
VESPA PX spec is typically around 500 ohms with min spec of 470 ohms. The higher resistance is because the VESPA system typically runs at lower rpm and to create sufficient voltage more turns of thinner diameter wire are used. If you use this system to drive two CDI boxes at higher rpm it can overload the coil. I thought the over voltage protection was there to protect the CDI but it may also help to prevent overloading the coil by restricting the voltage. Nevertheless it's there for a reason.
Full height bobbin should be available, this then should be rewound with 0.15mm wire which should conform to at least 150c operation. The number of turns is around 3000 I believe but usually the winder just packs the bobbin. Resistance measured will not be as high as 300 ohms, but around 270 ohms. If they are winding bobbin with 470 ohms then it is not right.

There remains the possibility that there is a fault with one or both the CDI which could cause excessive load to be taken, the input resistance of the CDI green wire to ground should be high, tens of K ohms.
It could also be a fault with the thyristors not turning off properly this can be seen only with an oscilloscope.
George Lane (see ad in ATG) may be able to help with winding.

Mark

[Fastmongrel]

Thanks for the information I didn't understand the 2nd paragraph but it gives me information to speak to West country windings.

I will look up George Lane.

[MickeyMoto]

With the ignition on there is a DC voltage on the green lead, off there is nothing. Looks like you disconnected the green lead to measure. As far as I am aware, there should be no DC voltage present on this coil. Do you have a problem in the alternator? I believe when switched on 12 volts is put into the alternator, I think it is the red wire. If you disconnect this then measure again with ignition on what voltage do you get on the green lead?


Is the coil open circuit or short circuit now? ie what resistance do you have now?

[mbmm350s]

Hi Mike
I am sure you know this as do many but I am repeating this for the benefit of others who may read this later.
If d.c 12V d.c is on the green wire and the motor is kicked over this puts the thyristors into terminal conduction and causes failure of both CDI boxes.
12v d.c across the green of the generator with CDI boxes disconnected will not harm the winding as V^2/R is only 144/300 and can be dissapated without problem.
What is potentially more problematic is the unregulated a.c of the yellow getting onto the green.
With everything disconnected resistance measurements between green and all yellows and red these should all be open circuit. If available an insulation tester should be used to confirm.
Any competent winding company should confirm the insulation tests pass.

Mark

[Fastmongrel]

With the ignition on there is a DC voltage on the green lead, off there is nothing. Looks like you disconnected the green lead to measure. As far as I am aware, there should be no DC voltage present on this coil. Do you have a problem in the alternator? I believe when switched on 12 volts is put into the alternator, I think it is the red wire. If you disconnect this then measure again with ignition on what voltage do you get on the green lead?


Is the coil open circuit or short circuit now? ie what resistance do you have now?

Voltage on green wire with red wire disconnected

Compress_20230925_105007_7150.jpg (206.72 KiB) Viewed 2478 times

Resistance on green wire with red wire disconnected

Compress_20230925_105008_8086.jpg (210.04 KiB) Viewed 2478 times

[Fastmongrel]

With everything disconnected resistance measurements between green and all yellows and red these should all be open circuit. If available an insulation tester should be used to confirm.
Any competent winding company should confirm the insulation tests pass.

Mark

All wires disconnected and ignition on
Green wire to red wire= open
Green wire to 1st yellow wire = open
Green wire to 2 nd yellow wire= open
Green wire to white wire = 305 ohms
Same result with ignition off

Compress_20230925_110725_5714.jpg (140.95 KiB) Viewed 2477 times

Compress_20230925_110725_5104.jpg (191.59 KiB) Viewed 2477 times

[mbmm350s]

With everything disconnected resistance measurements between green and all yellows and red these should all be open circuit. If available an insulation tester should be used to confirm.
Any competent winding company should confirm the insulation tests pass.

Mark

All wires disconnected and ignition on
Green wire to red wire= open
Green wire to 1st yellow wire = open
Green wire to 2 nd yellow wire= open
Green wire to white wire = 305 ohms
Same result with ignition off

Green to yellow as expected, open circuit. An insulation tester would be needed to confirm that there isn't an insulation fault (unlikely if the wires have been replaced)

The green to white/earth has reduced from 470 ohms to 305ohms, indicating that many turns are shorted due to insulation breakdown.
The loss of turns, and overheating will mean reduced voltage to the CDI and hence no or intermmitent spark

I haven't located a bare CDI bobbin of the correct large size, however there are the large lighting coils (PX series Vespas with electronic ignition) I think these are the same size available which can be unwound and the bobbin re-used
I would try Wasp performance, or SIP or Beedspeed.

Thanks for the information I didn't understand the 2nd paragraph but it gives me information to speak to West country windings.

Full height bobbin should be available, this then should be rewound with 0.15mm wire which should conform to at least 150c operation. The number of turns is around 3000 I believe but usually the winder just packs the bobbin. Resistance measured will not be as high as 300 ohms, but around 270 ohms. If they are winding bobbin with 470 ohms then it is not right.

The insulation class I think needs to be H, this spec is for 180 degrees at 20,000 hours, if we anticipate that the true operating temp is around 120c-130c then the operating lifespan of the insulation is doubled for about every 10 degrees cooler than class spec. This gives an expected lifetime of tens of years. If we used F class we might have an expected lifetime of less than 10 years, not advisable.
The original wire is "solderable", meaning the insulation is readily removed by soldering.

Mark
Electrical Engineer Bsc Eng.

[Fastmongrel]

I am tempted to buy a wire winder a reel of the correct wire and have a go myself. Has anyone got any experience of this type of winder it's cheap so not expecting much.

Manual Coil Winder Counter KATSU Copper Wire Winding Tool for Audio Output Transformer Mechanical Counter 990722 https://amzn.eu/d/0zU0oe7

[lemans]

I am tempted to buy a wire winder a reel of the correct wire and have a go myself. Has anyone got any experience of this type of winder it's cheap so not expecting much.

Manual Coil Winder Counter KATSU Copper Wire Winding Tool for Audio Output Transformer Mechanical Counter 990722 https://amzn.eu/d/0zU0oe7

waste of time and money. you'll also need the bobin to wind the wire on. which is not commercially available in dimension and small quantity, so you need to make your own. It can be done with good results but takes a lot of time.
how do I know, tried it myself.