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Discussion Starter · #1 ·
I have a 1980 CX500. I just cleaned the carbs and replaced the parts that looked bad including new jets. Got it started and it's running badly. so...I checked the plugs and the right side is getting spark, but it is yellow spark (indicating less coming from the coils). The left side is not showing any spark visably but if I pull the plug wire when running it runs worse. I changed the pink and yellow wires to the coils and the left side shows spark (again...yellow) and the right doesn't. This would indicate to me that the coils aren't the problem. Does this sound like a CDI problem? Thanks...Bob
 

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A cdi can produce a flaky spark problem but more diagnosis is needed. Also put your location in your profile so people know where you are. They might have a cdi that you can borrow.
 

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Well if it were summer I would jump on the bike and head down to your place so you could try mine. But it's cold.



And it's a pain to get to your area from 94. Mike "I'm going to GL" lives in Island Lake so I've been down there a few times. Seemed like it took forever after I got off the toll road.
 

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You need to test the stator to rule it out.



There is a plug under the seat with a blue wire and a white wire that comes from the stator and plugs into the cdi, unplug it. Place the neagitive lead from your volt meter on a ground or the negative post on the battery and the positive lead on the spade connector of the white wire. When rolling the engine over on the starter, with the spark plugs out and a fully charged battery, you should read approx. 70-90 AC volts on the white wire from the stator. Your readings should be slightly higher on the blue wire.



You can also test the resistance on the other wires that come from the stator,,[url="http://cx500forum.com/index.php?/topic/2972-electric-problem-maybe/?quot;]see this thread[/url] for how to do those tests.



If the stator tests ok your problem is likely in the CDI.



As blindstitch has said if you can find someone nearby who has one it is

easy to swap the cdi to know for certain.
 

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Discussion Starter · #9 ·
I ran a stator resistance check on the stator (yellow wires) and, they are all at 1 ohm or a bit less.

When running a voltage test from the blue and white wires coming from the stator I got 76 and 93 volts.



Stator voltage is supposed to be checked at 2000rpm, but I can only keep the engine steady, right now at 3000 rpm. They read an average of 90V but maybe that would be less at lower R's.



I have not sync'd my carb's (recently cleaned and replaced seals and parts) Only having made a check on each side independently while running, they are out of sync. (Only had one vacuum guage, but will get another, soon)

...and this may be part of then problem keeping it running at low R's.



As stated above, when I switched the yellow and pink wires to the coils, the visable spark from each side switched.



When checking resistance at the cdi :



RH lowspeed coil Supposed to be (95-116) tested at 119

RH high speed coil (81-99) tested at ...............101.5

LH adv pulser (185-225) tested at ..................221

LH low speed coil ((95-116).........................1 (infinity?) at all meter settings

LH high speed coil (81-99)..........................100.

RH Adv pulser (185-225).............................225



Source coil high speed (77-950......................88

Source coil low speed (387-473).....................359



Hoping you can tell me what this means...

I'm guessing that since the left low speed coil is bad and since I'm having trouble with low rpm spark on the

left side that the problem is in the cdi. ?????
 

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When checking resistance at the cdi :



RH lowspeed coil Supposed to be (95-116) tested at 119

RH high speed coil (81-99) tested at ...............101.5

LH adv pulser (185-225) tested at ..................221

LH low speed coil ((95-116).........................1 (infinity?) at all meter settings

LH high speed coil (81-99)..........................100.

RH Adv pulser (185-225).............................225



Source coil high speed (77-950......................88

Source coil low speed (387-473).....................359



Hoping you can tell me what this means...

I'm guessing that since the left low speed coil is bad and since I'm having trouble with low rpm spark on the

left side that the problem is in the cdi. ?????


When you were doing the resistance checks were you testing the side of the connector that comes from the stator(male) or the side that goes to the cdi?



The values listed in the diagram are for the side of the connector that comes from the engine or stator.







If you were testing the stator side, it seems your stator is bad.
 

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Island Lake is really close! Think Mike might be able to help? I've tested the stater and seems to test out O.K. Bob


I missed this but he doesn't have a cx.



If/When it gets better I will be willing to take a run down there.
 

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Discussion Starter · #12 ·
I was testing the male ends that come from the stator and I was using the #5 male end as the ground. Should I have used the battery ground instead? If it is the stator, that's too bad, because I just bought a used cdi....but I'll be glad to have an extra or since he gave me a decent price, sell it.

If this is a stator problem, I guess I'll find out when the cdi gets here. Would an ignitech ignition be a problem solver?

I've pulled and worked on a BMW K1100LT engine and after THAT am capable of a quick pull out of the cx to change the stator.



You wouldn't believe how complex the BMW was . Everything is put together so compactly, that it drives you crazy putting it back in. Great machine though....I've been to Atlanta and Phoenix without a blip on it!



Electrical problems are very new to me and I'm really enjoying getting to know the the meter and finding problems with you guy's (es) help...



Thanks for that and the offer to come here, but of course I would gladly go to you to play with it...It seems to run decent at higher r's, just too cold to find out. Bob
 

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If this is a stator problem, I guess I'll find out when the cdi gets here. Would an ignitech ignition be a problem solver?


yes, ignitech would solve your problem as long as your stator is charging the battery OK.
 

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I hope it is ok to bring this thread back to life.



Hi, I just bought a '81 cx500
I always wanted one of these crazy lookin things.



Sorry for my first post on this forum to be a tech q, but I need help already!





My bike start easy but will not rev above 3-4000rpm with lots of popoing/ banging. The prev owner thought it was the source coil and had it rewound at big expense.



I've done some testing, with the (so helpful) info above and the "lh high speed coil" comes up dead - and the rest of the plug tests seem to be within range.



So what is my best course of action from now?



Pull the lh speed coil and see if it has failed or the wiring to it? If it has failed, where is a good source of another?



thanks for just thoughts

scott
 

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i will do = thanku for the feedback.



I have tracked the LH high speed coil back - and it is one of the wires that goes into the case




i'll keep reading..



with high and low speed source coils, high and low advance pulser and hight and low speed coils could Honda have made this ignition more complicated !!?

(seriously I had a honda h100 of the same era (1980) and it had a very basic 4 wire CDI - which ran great)



BTW if my lt high speed coil is dead (i guess it is the lt high speed trigger - once activated by the high speed coil sensor) will a Ignitech box fix this not does it still need this sensor/trigger?
 
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