Do I have an ignition problem

[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

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.

I was thinking of using the original bobbin unwinding the original wire cleaning the bobbin in the ultrasound bath and then taking my time winding on.

[lemans]

the bobbin might come apart, new ones are hard to come by, unless you make your own.

[MickeyMoto]

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.

Mark,

Is not the white wire the 'earth' for the stator? Does this not attach to the transducers to ensure they are directly connected to the other end of the winding? Mr Fast appears to have 250k Ohms from Green to his clip on the barrel but 300 Ohms from the green to white. Shouldn't he get short circuit from white to engine, therefore he should get the same reading from green to white and green to the barrel (within a few ohms)?

I know earlier bikes did not have the white wire.

Does he need to check his engine is earthed correctly?

[Fastmongrel]

Just checked the engine earth and I get 0.1 ohms between engine barrel and negative battery terminal. Also get the same resistance engine barrel to frame.

Is this the correct reading.

[mbmm350s]

[/quote]

Mark,

Is not the white wire the 'earth' for the stator? Does this not attach to the transducers to ensure they are directly connected to the other end of the winding? Mr Fast appears to have 250k Ohms from Green to his clip on the barrel but 300 Ohms from the green to white. Shouldn't he get short circuit from white to engine, therefore he should get the same reading from green to white and green to the barrel (within a few ohms)?

I know earlier bikes did not have the white wire.

Does he need to check his engine is earthed correctly?
[/quote]

Good points Mike,
yes white is earth, note it has small gauge so is not intended to carry much current.

I took the 250K measurement to mean with the green connected to the CDI boxes IGNITION ON, but disconnected from the stator, which makes sense as they have internally a potential divider for the tacho output, but we need to confirm.

Green to chassis should be lets say 200 to 300 ohms Ignition ON, < 1ohm IGNITION OFF
Green to white as above
white to chassis/engine < 1ohm ignition switch doesn't matter
battery to chassis and engine < 1 ohm ignition switch position doesnt matter

sadly I don't have any spare bobbins, may by Paul (evguru) has some.

Mark

[MickeyMoto]

Just checked the engine earth and I get 0.1 ohms between engine barrel and negative battery terminal. Also get the same resistance engine barrel to frame.

Is this the correct reading.

0.1 is basically a short so that is good

What do you have from white wire to the battery negative terminal?

Just for completeness, what do you get from battery -ve to the stator back plate? I hope a short as it screws into the engine.

I like to check everything!! I chased an electrical fault once, couldn't resolve it so went back to first principles and methodically checked everything. My biggest bugbear on the Morini is the earth bolts either side of the headstock. I always emery the paint off around the hole and clean all the terminals before bolting up.

Good luck with rewinding the coil. I wonder if West Country Windings have new employees as they have moved since I used them. They used to be near Bishops Stortford in the middle of nowhere.

Anybody tried Robson and Francis in London?

Thanks,

[RobinSF1]

No personal experience of Frances and Robson, but our mutual acquaintance lemon jelly recommended them after he had some laverda work done there.

[Ming]

Look on thr Dutch Morini site for a diy coil rewind. Not difficult, a bit tedious, I doubt the old coil former is salvageable.

[MickeyMoto]

No personal experience of Frances and Robson, but our mutual acquaintance lemon jelly recommended them after he had some laverda work done there.

Thanks, Robin.

Since Rexs Speedshop stopped winding and now it looks like West Country Windings may have changed, it would be nice to have other choices.

[Fastmongrel]

http://www.robsonandfrancisrewinds.co.uk/index.html

[mbmm350s]

Look on thr Dutch Morini site for a diy coil rewind. Not difficult, a bit tedious, I doubt the old coil former is salvageable.

ah Ming you are very modest, this splendid article is exactly what the O.P would need to rewind the bobbin. The antique grinder a stroke of genius.

Based on that I think that 0.1422mm (35 AWG) would be perhaps more suitable than 0.15 (38SWG) for hand winding where we can never get the packing of automated winding machines.

I would prefer to use solderable polyester 180c (20,000 hours) instead of the solderable polyurethane supplied by wires.co.uk which is 155c (20,000 hours), but I am more used to designing systems that are in continous operation for 25 years...
non-solderable is hard to use for fine wires there is too much risk of damage when scraping off the insulation.

https://brocott.co.uk/0-14mm-35-awg-ena ... rable-500g

Just need a source of the tall generator bobbins...

Mark

[Steve Brown]

Look on thr Dutch Morini site for a diy coil rewind. Not difficult, a bit tedious, I doubt the old coil former is salvageable.

ah Ming you are very modest, this splendid article is exactly what the O.P would need to rewind the bobbin. The antique grinder a stroke of genius.

Based on that I think that 0.1422mm (35 AWG) would be perhaps more suitable than 0.15 (38SWG) for hand winding where we can never get the packing of automated winding machines.

I would prefer to use solderable polyester 180c (20,000 hours) instead of the solderable polyurethane supplied by wires.co.uk which is 155c (20,000 hours), but I am more used to designing systems that are in continous operation for 25 years...
non-solderable is hard to use for fine wires there is too much risk of damage when scraping off the insulation.

https://brocott.co.uk/0-14mm-35-awg-ena ... rable-500g

Just need a source of the tall generator bobbins...

Mark

Somebody did 3D print some. Others here have been doing various 3D print projects too.

[Ming]

Re using smaller diameter, self fluxing wire I agree. I think I may have mentioned it towards the end of the article. Whatever, it worked fine. A few 3D printed formers (not a common technology back then) would be no problem for some of our more up to date members, I think. I still have the grinder...

[Fastmongrel]

I have been in contact with West country windings and they say the specification they use is the same for all Morini source coils and they have never had any returns before.

I am now at a complete loss what to do next I have been all over the bloody bike with my multi meter cleaning wiring connections and earth's. I have even put the original sloppy ignition switch back on.

I can see this bike going on eBay

[72degrees]

I have been in contact with West country windings and they say the specification they use is the same for all Morini source coils and they have never had any returns before.

I am now at a complete loss what to do next I have been all over the bloody bike with my multi meter cleaning wiring connections and earth's. I have even put the original sloppy ignition switch back on.

I can see this bike going on eBay

Odd, because the ones they have done for me have never had as high a resistance (470 ohms) as you originally tested it at. The last rewind I had was done by Rex's speed shop though - which has been fine.

"I can see this bike going on eBay."

Or if you break it, has it got an electric start ?