Petter A Series II - Wico A Magneto Issues

Blue Cat,

Thank you for your message and the wiring diagram.

I can confirm that I do not get a continuity buzz when testing across either of the the two new condensers (X1413 or the EasyCap modification) on the bench.

Surely you should not get a continuity buzz between the moving breaker/primary coil  contact point and the magneto case when you have cardboard between the points?

Would this not in effect be the same as pressing the magneto stop switch?

With cardboard between the points I only get the a continuity buzz between the moving breaker/primary coil contact point and the magneto case when I install either of the condensers.

I look forward to your reply.

Blue cat, I'm glad you have been able to provide David with the basic circuit diagram and the expected test results for the magneto. It is exactly what I was attempting to do but with much less clarity, when you beat me to it. I have not yet mastered the drawing skills on the P.C.

Hopefully your diagram with its clear description of functionality, will provide David with the information he requires to be able to hunt down his issues.

Over to you David.

Neil.

This maybe a silly question but have you checked the insulators on the points assembly, do they exist or are they breaking down.

Maryalice

Maryalice,

The insulation at the moving breaker/primary coil contact point is good and the insulation strip around the edge of the housing is also good.

Blue Cat,

Sorry, I missed your edit and have just checked the resistance between the moving breaker/primary coil contact point and the magneto case and I am getting a reading of 0.005 on the 200 ohm scale (which I believe equals just 1 ohm).

I get the same reading with or without a condenser in the circuit.

That leads me to think that you have an insulation issue, pinched trapped wire for instance.

Is the impulse spring releasing at the correct moment to generate the spark. All this explanation of what is where and why and readings just makes me glaze over so I can’t help with that.

On that basis is the magneto 180 degrees out.

I must admit that I was surprised at blue cats reading for the contact breaker to earth. I wonder if the decimal point is in the correct position, I would have expected a reading more like 1.2 - 1.5 ohms. If you look at my earlier post the reading showing on my meter is 1 ohm. In fact that represents an actual measurement of about 0.7 ohm as the meter cannot be zeroed and with the leads shorted together there is a standing reading of 0.3 ohm. Obviously that will cause a strong buzzer sound due to the low resistance being presented.

There is a big difference when the cut-out is operated as this shunts the primary directly to ground. Whereas the primary coils have a very low internal resistance but still produce a voltage difference across the coil when energised by the moving magnet.

Hope this helps to explain the difference.

Neil.

I can feel the frustration with this, for me personally at this stage I'd be stuffing it in a mates hands and telling him to give me it back in working order for a pint

Gents,

Maybe I have just been too focused on the primary coil lead in the breaker housing going to ground (magneto case).

I guess I could not get my head round the upstream 'stop switch' that when operated effectively goes direct to ground (magneto case) and stops the spark generation.

I will now reassemble and add the new EasyCap condenser and see if I can get it sparking.

djpeng wrote:Blue Cat,

Sorry, I missed your edit and have just checked the resistance between the moving breaker/primary coil contact point and the magneto case and I am getting a reading of 0.005 on the 200 ohm scale (which I believe equals just 1 ohm).

I get the same reading with or without a condenser in the circuit.

Yeah, I rechecked the reading and I now get about 3 ohms. Possibly my old meter is not accurate at this low reading, or maybe it needs new batteries.

neil (LE) wrote:I must admit that I was surprised at blue cats reading for the contact breaker to earth. I wonder if the decimal point is in the correct position, I would have expected a reading more like 1.2 - 1.5 ohms. If you look at my earlier post the reading showing on my meter is 1 ohm. In fact that represents an actual measurement of about 0.7 ohm as the meter cannot be zeroed and with the leads shorted together there is a standing reading of 0.3 ohm. Obviously that will cause a strong buzzer sound due to the low resistance being presented.

There is a big difference when the cut-out is operated as this shunts the primary directly to ground. Whereas the primary coils have a very low internal resistance but still produce a voltage difference across the coil when energised by the moving magnet.

Hope this helps to explain the difference.

Neil.

Yeah, I rechecked the reading and I now get about 3 ohms. Possibly my old meter is not accurate at this low reading, or maybe it needs new batteries.

djpeng wrote:Blue Cat,

Thank you for your message and the wiring diagram.

Surely you should not get a continuity buzz between the moving breaker/primary coil  contact point and the magneto case when you have cardboard between the points?

Would this not in effect be the same as pressing the magneto stop switch?

No, the primary is a mini circuit by itself. The stop switch short circuits the coil preventing current generation in the primary circuit.

Gents,

Good news at last - after my steep 'magneto' learning curve and the 'EasyCap' condenser modification my engine is now starting each time on the first pull and seems to be running fairly smoothly (as far as I can tell!!).

I had some fuel feed issues to resolve which turned out to be a very mucky mesh filter in the top of the Wipac sediment trap.

I also managed to get the magneto initially installed 180 degrees out and was rewarded with a backfire but at least this was a sign of engine life!!

I apologise for this very lengthy magneto saga and thank everyone for their patience, advice and assistance - you are never too old to learn.

See, I said "... keep at it I'm (fairly) sure you will get there", in one of my previous posts! Greatest feeling when you succeed after a lot of trials and tribulation, that's what makes it all worth while.

Did you actually find out what was wrong, apart from getting it 180 degrees out this time, or will that remain a mystery?

Neil.

Neil,

I think at the end it was a condenser issue but on the way I got very hung up on the primary coil lead going to ground (magneto case) and that my understanding that this was the same as operating the magneto stop switch and the killing spark generation.

The diagram that Blue Cat provided was very helpful and made me ignore some of my concerns.

So the 'EasyCap Modification' that I am using is the CU220 which seems to work fine now.

Again, thank you for your patience and advice.