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Lighting and Electrical Things that go ZOT! Ignition components, batteries, lighting and accessories for your motorized bicycle


testing a magneto?

Things that go ZOT! Ignition components, batteries, lighting and accessories for your motorized bicycle


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  #1  
Old 03-03-2011, 12:42 PM
matthurd matthurd is offline
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Default testing a magneto?

2 weeks ago i was having no spark, got around to ordering some parts, ordered a new cdi because a few people here said they go more often then magnetos, anyways it didn't fix the problem so i opened the magneto panel and apparently some water and road salt had gotten in there and i'm guessing it's fried now. not sure how it got in it wasn't a very wet day the one time i rode it, and i had never opened that panel before today so the gasket should have been safe and solid.

anyways before i go and order another part that i actually don't need (although i'm pretty sure i do) i'd like to test it. new cdi new spark plug and no spark.

any ideas how to test it? my dads a former electrician so he has a few good meters if those are needed.

and how can i prevent anything from getting into that compartment in the future.

searching magneto testing didn't work very well for me so figured i'd ask, thanks.

guessing this is dead right?



Last edited by matthurd; 03-03-2011 at 01:09 PM.
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Old 03-03-2011, 01:34 PM
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earl.k earl.k is offline
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Default Re: testing a magneto?

i read some place. that the small wire shown below in the pic. can sometimes go bad or come broke..



this could be your problem.. also do you have your kill switch hooked up.. because if it is grounded wrong. this will also cause it not to spark.. i have grounded mine wrong and know its a easy fix.. never hade a bad magneto, but if it is that wire im betting you could just mend it easily. or buy a new magneto.. good luck and here is another pic of a working magneto.





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Old 03-03-2011, 02:45 PM
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Default Re: testing a magneto?

junky ass china seal job
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Old 03-03-2011, 02:46 PM
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Default Re: testing a magneto?

If you have an ohm meter, your dad will know how to use it, try this:

Use Low Ohm-Meter Scale About 200 Ohms

Magneto Coil

1) Check Ohms between BLACK wire and WHITE wire. Reading should be around 2 Ohms
2) Check ohms between BLUE wire and WHITE wire. Should be around 300-400 ohms.

CDI

Use Ohm Meter High Scale About 200-K
1) Positive lead on BLUE wire and Negative lead on BLACK wire should read infinite (no activity)
2) Positive lead on BLACK wire and Negative lead on BLUE wire. Should be about 130-150 K-ohms
3) Positive lead on Spark Plug wire and negative lead on BLUE wire. Should read between 135-155 K-ohms

Switch to Low Scale 20K
4) Measure between Spark Plug wire and Black lead. Should be about 2.5 - 2.7 K- ohms

As for keeping water/dirt out. Make sure the gasket is good or seal it with a small bead of silicone and fill the hole where the wires exit the case with the same silicone sealer.

Tom
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Old 03-03-2011, 02:48 PM
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Default Re: testing a magneto?

the best way to test is with your nose does it smell burnt if not they do have ground problems try starting it with the kill switch pushed
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Old 03-03-2011, 03:04 PM
matthurd matthurd is offline
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Default Re: testing a magneto?

@earl the little wire and all other solder connections appear to be solid

@taco yeah the gasket basically crumbled in my hand

@2door ordered a new gasket from pirate as well as a new magneto but i guess testing to learn is never a bad thing, if it works i just have an extra and i need the gasket anyways, and do i need to be rolling the bike while he tests this or is this supposed to be done while stationary?

@adam it doesn't smell burnt, kill switch start is a no go although honestly i never had it working right in the first place this didn't stop me from starting it originally though, i did have it working originally.
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Old 03-03-2011, 03:07 PM
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Default Re: testing a magneto?

stupid question but do you have your white wire taped up????
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Old 03-03-2011, 03:08 PM
matthurd matthurd is offline
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Default Re: testing a magneto?

nope no tape on anything atm.
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Old 03-03-2011, 03:10 PM
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Default Re: testing a magneto?

Quote:
Originally Posted by matthurd View Post
nope no tape on anything atm.
tape the white wire so it don't ground out and go try to ride your bike lol
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Old 03-03-2011, 03:18 PM
matthurd matthurd is offline
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Default Re: testing a magneto?

tested no good with tape,
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