Mobylette magneto

Kevin Ibbetson /

40 v mobylette, '71. Anyone know how much voltage should I be able to measure if I connect a voltmeter across the two magneto outlets? I'm getting just a blip on the meter, maybe that's why there is no spark????

Re: Mobylette magneto

I am a fellow motobecane owner. I too would love info on how to correctly test coils. coils have always been a little bit of a mystery to me and most moped riders. Both fred guide, and my mobylette shop manual have no information on coils besides "if it does not work, replace it" They are always the one thing I can never confirm when troubleshooting.

Re: Mobylette magneto

Steve Murphy /

The basics of how it works are simple and you probably know it already: The flywheel has a magnet on it's inside. As the flywheel spins, the magnet passes close to the stator coil, inducing a voltage across the coil. The level of the voltage varies with the number of windings, the strength of the magnets, and the speed of the engine.

Measuring the voltage out of the coils is not that easy on a non-running bike, since the coil only has output while the magnet is passing through it's field. Chances are that the coil is probably OK if your meter shows a couple of volts on these blips while hand-cranking the engine.

You can disconnect the coil and check its resistance. It should be fairly low, but not a dead short. I don't want to guess at a value for your Moby; I've never measured a Moby coil and don't want to give you bad information.

There's only three things that could go wrong with the coil: it could be physically damaged (broken, water damaged, etc), it could go open (infinite resistance), or it could short (zero ohms).

It's important to keep the coils flywheel and all the wiring and connections clean and free from dirt, grease, rust, etc. As long as you do this, they're pretty much bulletproof.

Re: Mobylette magneto

Kevin Ibbetson /

Thanks a lot for the info on the magneto Steve, I'll keep at it. Kevin

« Go to Topics — end of thread

Want to post in this forum? We'd love to have you join the discussion, but first:

Login or Create Account