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WDRE 125 Flying flea sparking problem.

Alan S

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Hi all,

I'm looking for some technical help.

Really struggling to get a spark and so far I've done the following.


HT lead and cap

Spark plug 



Recoiled magneto (done by an ex Lucas employee)

Checked and double checked points and plug gap 0.015

Set timing to tdc and points about to open.


All the above tested on a bench

Multimeter continuity testing all ok

Multimeter tested end of HT lead, got between 2 & 9v depending on how hard I turned it over.

Everything appears to test fine until I plug in a spark plug, earth it on the head bolt and nothing!

Any help or suggestions greatfully received.


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Posted (edited)

The obvious first thing is, have you tried different plugs? Also when earthing the plug, the end of the HT lead must be clear of the earth point. You should get a spark from just the end of the HT lead when held 1/8" or so from an earth point. Ron

PS I'm not sure how you test the HT with a multimeter? The spark generated by the magneto is in the Millivolt rage...Hence the shock if you touch it. Maybe someone with more electronics experience can advice?

Edited by Ron
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Posted (edited)


This problem could be one of many possible faults.


As Ron mentioned: the HT volts will be in the kV range ... somewhere upwards of five thousand Volts reaching to twenty thousand .Multimeters usually don't measure that high a  voltage . Keep your hands well clear of the HT ... it can give you a nasty surprise.  


This might help 



More science 


Edited by goanna
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  • 2 weeks later...

This is someone else who asked a question and then just disappeared. It used to be known in the services as "Dumb Insolence"   Ron

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