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CX500 not sparking - Smoking top of Regulator

7094 Views 45 Replies 12 Participants Last post by  marshallf3
just picked up a 79 CX500 with 30k miles on it . I'd like to give a big shout out to all ye CX500 owners ! I've already met alot of you online

has the CDI ignition , things i've checked are . kill switch ok , starter button ok sending voltage to the yellow/red wire to solenoid when i push the start button(new Starter Solenoid coming in mail this ones not working) . when i jump the solenoid she cranks over fine but i get no spark .. shouldnt it be sparking? pulled plug and have it grounded to bike at a good ground. also i have cleaned the ignition coil connections on both coils to make a good ground. so my question is shouldnt it be sparking by jumping the solenoid? These are new NGK plugs .. old one not sparking either. I did also check for voltage at the coil wire connection before coil to see if getting any voltage to it .. nada. oh and i also did check the flywheel through the timing hole on the engine to make sure its turning .. yup its turning.

also i have read about the neutral switch . i do get a neutral light when electric is on . that wouldnt make it not spark would it? also checked the pickup coil continuity o/w wire to lt blue/white wire on the engine side. i also checked for some AC voltage at these wires when cranking by jumping the starter relay and its getting voltage there. Its cranking over fine , i even tried to jump it with my car battery still no spark so not battery related.

something with the CDI or Stator related me thinks ? oh also i did think of something else . i did have the front head light/instrument cluster on but it wasnt all hooked up with the ground. i have left it off unconnected until i paint it .. do i need that on and grounded right for it to spark ? just a thought , seems to me if i'm getting voltage at the starter relay solenoid when i push the start button it should be ok and crank over and spark eh? i have been wrong before tho .. once i think

looking forward to continuing this CX500 resurrection
.. haha any help apprieciated.

what my bad boy looks like now

Pic 1

Pic 2

when i get done with her it will look like this one

Pic 3
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There are wires that come from the stator to the cdi,they plug into the CDI under the seat, 1 of the plugs has a blue wire and a white wire, if you unplug that plug and test the voltage coming from the stator when cranking the engine over you should have 80 or 90 volts on the white wire and 100 or so on the blue wire.

If you get substantially lower reading on the white wire(less than 60 volts) there may be a problem in the stator.

There is another plug under the seat that has 3 yellow wires, they come from the charging windings on the stator and plug into the regulator/rectifier, you can unplug that plug and try starting the bike. If the bike starts with that unplugged then there is probably a short to ground in one of the charging windings.

If there is nothing wrong with the stator, you can do a quick test on the cdi, there should be approx. 150 volts on the pink and yellow wires coming from the CDI to the coils when cranking the engine over.

There are more thorough tests for the stator but try the above first and let us know what the results are.
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It does sound like the CDI is causing your problem,,it would be good if you could find one to try on your bike to be 100% certain before buying another though. Or you could try your CDI on a known runner to test it that way too.

Did you try unplugging the kill switch? It is the black wire with a white stripe that plugs into the CDI.
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kinda strange because i tested the kill switch and it was going on and off with power when i was testing it at the switch so not sure whats up with thtat switch maybe just need to clean up that bullet connector on this new CDI box . the CDI box bullet connection maybe, but it was indeed the CDI box .. thanks to all that helped me figure this one out

I would try the other CDI again before you toss it.

There is no power from the kill switch, it grounds the CDI to stop the engine.

There may be a short in the kill switch wire. If there was a bad connection at the kill switch bullet connector it would be the same as having the wire unplugged, the bike would run but would not shut off when you turned the kill switch off.
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