I have a Wipac Series "A" magneto on my Dennis lawnmower. I didn't
realise until I got this magneto that the Series "A" had been sold under
the Wipac name.
Anyway, it isn't working properly. The spark is incredibly feeble. It
won't cross the plug gap. I can only just see the spark if I hold the
end of the HT lead about a tenth of a millimetre away from the magneto
body. So the spark is there, but it's pathetic.
The magneto's got an impulse coupling, so it should produce a decent
spark at a low speed. It doesn't produce a spark through the plug at all
when the engine is turned at a sensible cranking speed.
Overall the magneto looks in good condition. It's been stored in a damp
environment for a few years but inside it looks great. Like new in fact.
I cleaned the breaker contacts. They look good. A miniscule amount of
pitting is visible. The contacts measure 0 ohms when closed (measured
with a digital multimeter), and they open properly. The HT coil measures
4860 ohms from the HT terminal to the magneto body.
I thought perhaps the HT coil insulation had failed, so I tested it with
a megger (one of the great old mechanical ones). I had to disconnect the
"earth" end of the HT coil from the magneto body to do this. The
resistance between the HT coil and earth (its iron core) is between 30
and 40 megohms. To me that sounds good.
I also meggered the condensor to see if it had failed in the short
circuit condition. It measures 40 megohms.
Can anyone think what might be wrong with this magneto? I really can't
figure it out right now.
13 years ago