Fly Wheel Magneto test

Jason Sankey /

1980 Vespa Grande:

No spark at the plug--> cleaned points, bypassed any switches and or kill switches. Still no spark. So i just now used a volt meter (DC 20 setting). I attached the ground to the metal on the motor, and the pos to the wire that comes from the flywheel magneto and before the HT coil. Still nuthin. 0.00. If anyone has any other things to test. Please let me know.

I thank you much,

::Jason

Re: Fly Wheel Magneto test

FWIW, that's an AC magneto. You might see some blips on a DC meter, but it won't read the AC.

And even if it is an AC meter, most of them are calibrated for 60Hz power. Not the high-frequency power produced by a magneto.

Re: Fly Wheel Magneto test

Jason Sankey /

My testor does have AV settings, I guess i did'nt figure power ever went back into the magneto. The AV has two settings, 750 and 200. Will either of those work?

Re: Fly Wheel Magneto test

Jason Luther /

the spark coil inside the magneto puts out maybe 1.5-2 volts, so no, you wont see that on your meter. look inside your magneto for any melted, worn away wires that are touching anything besides your coils or points. long ends, pieces that are shorting out, anything. check the backsides of the wires that are touching the stator plate itself, they could be melted on that side. are you sure your ht coil is grounded?

Re: Fly Wheel Magneto test

Jason Sankey /

Well, heres the update. I did have power going to a wire that run to the rear brakelight. It did in fact show up on the meter. So i ran that power to the HTcoil. and yes, there was a spark at the plug when pedaled. So this tells me the flywheel magneto is working. So now i'm going to investigate the wire like said in the reply from jason. I gotta figure out how i'm going to get in there to check the wire end inside the case. (about 4 wires i think go into the case through a hole in the top of the metal case.) Any clues or stratigies?

Re: Fly Wheel Magneto test

Jason Luther /

i have never seen a vespa, but all of the peds i have seen have a cover that covers the magneto. remove that and then you can see in there. you will probably have to remove the magnet its self to gain access to the wires. and this is where i leave you.

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