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Flywheel advice needed

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Flywheel advice needed

Post  Mollbhan on Sun Jun 11, 2017 10:10 pm

Hi, I have a 59 Plover 30c engine has become almost impossible to start, fuel seems ok, spark at the plug seems feeble. I have carried out all the usual checks plug, points, timing etc, no improvement, the flywheel has six magnets in it, five of these seem to have a reasonable amount of pull, one does not, it has hardly any stick at all, is this normal? could this be the cause of the weak spark?    Frustration is beginning to set in.
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Mollbhan

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Re: Flywheel advice needed

Post  Druid on Tue Jun 13, 2017 3:41 pm

If your flywheel has one magnet that is almost completely demagnetised it suggests the other five will also have weakened considerably. However, if the magnet in question is the one that magnetically couples with the ignition coil approaching TDC because the magnetic flux will be low, the induced current will be low and subsequently when the points open the voltage induced in the HT coil will also be reduced. Hence the spark at the plug is likely to be weak/intermittent or non existent under the pressure in the combustion chamber.

As a test you could try reducing the plug gap to say 10 thou to see if this makes any difference, but it sounds like your flywheel requires re-magnetising.

Regards Dave.


Druid

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Re: Flywheel advice needed

Post  Mollbhan on Tue Jun 13, 2017 9:24 pm

Thanks Dave, checking in a better light showed the weak magnet to be made of a different metal from the others, I suspect the gap in the magnetic ring may be intentional. When I took the whole backing plate off I found it had been fitted with shredded remains of an old gasket behind it,leaking crankcase hence the oily mess in the mag/points area.I will try a new gasket before anything else. Fingers crossed.
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Re: Flywheel advice needed

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