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so at that black/white wire what should i be looking for in terms of a reading? its not disconnected
If it's connected that's good, the only possible thing to do there is to clean the contacts and reconnect them.

There's a frame ground wire from your CDI right? Is that connection clean and tight?
 

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83 Honda CM250C
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Discussion Starter · #62 ·
ya. but now i was thinking. my lights are all hooked up but i didnt have any headlights or brake lights. turn signals work though. i think it might be related. maybe by fixing that itll lead me to the issue
 

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Discussion Starter · #64 ·
Thanks I appreciate that. Curious, where do headlights get their power? I have the diagram but I can't make out where it's power source is. Obvious the battery but on a rebel, what powers the headlights to turn on?
 

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85 CMX 250C, 82 GW Remember that you are invisible, treat all others accordingly. Avoids Road RAGE!
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That is a complicated question with a complicated answer. If you're asking where it gets power nearby, it gets its power from the high low beam switch, blue & white wires which in turn get their power from a blue/white wire. If you are going further back, the blue/white gets its power from the brown/red through the ignition stop switch which comes from fuse number 2. This is on a 1st gen Rebel.
Fuse 2 gets its power from a black wire coming from the ignition switch. The ignition switch is powered by a red wire through the main fuse from the battery.
Guess this is "Adam to Armageddon" but the question was broad.
 

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But you've got a CM250, do you have a CM250 Factory Service Manual to work from?
There's one to download on that other forum I mentioned.
 

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83 Honda CM250C
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Discussion Starter · #68 ·
That looks stock to me, is it the original from your bike?

Some coils have more or less primary resistance than others, your CDI needs the correct coil to work properly.

Ok so I decided to test the coil again. With the caps on I'm getting a reading of 34k ohms and caps off I'm getting 7.69k ohms. Then on the primary I'm getting 0.9 ohms fluctuates to 3.5 ohms. So my guess is that's the culprate
 

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One thing that hasn't been mentioned is that this is a wasted spark system. Both plugs spark at the same time every time.

When you test for spark, is one plug screwed into the head with its wire & cap connected while you've got the other plug unscrewed from the head and stuck in its cap & wire, holding it against the head while you crank the engine and look for spark?

You might actually be getting a spark that you can't see too well with the room lights on.

Perhaps reduce your plug gap to test?


But yes those caps at least need to be replaced. If you've got any local motorcycle shops, they might have some 5K caps with the angle you want in stock.
 

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Discussion Starter · #70 ·
That's how I was testing it. Worked on cars for a long time before moving to bikes. But I found this and tested it this way.
Font Rectangle Material property Parallel Number
Font Parallel Schematic Auto part Engineering
 

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Yup, those GM coils are much better, they're just big.
 

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83 Honda CM250C
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Discussion Starter · #73 ·
Ok so I got that coil all hooked up and voila!
.......
Same thing......
For a laugh I decided to test the regulator...
Either it fried within the time of me hooking up the coil, or it died after I tested it before install.
I'm at a loss of words right now.
I unplugged everything from the harness to make sure I don't have a short to ground or short between wiring.
I'm going to get another reg/rectifier and pray that's the last thing I need to do. I'm tired of messing with this thing.
So I'll update as soon as I get another and I hope it's a happy ending otherwise I think I am going to throw in the towel.

When I was working at the repair shop, I was strictly smog, smog diagnosis. And complete diagnosis.(mechanical, electrical etc.) Towards the end of my tech career, for about 3 years I had a streak of not misdiagnosis a single car and diagnosing quickly, to the point the other shops came to me for help. Then one horrible day a Chevy Silverado 1500 came in with a simple air injection code on the check engine light. 7 days I spent on it and failed miserably. Every vehicle after that was either hit or miss. It took me 4 months to finally snap out of that failure feeling. Then I got Hurt and now I'm working on bikes and that feeling of failure is looming it's ugly head over me and it's really bumming me out. But I digress.. .. .

I'm pretty sure this will fix it for good. Lol
 

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You've come this far & spent X amount of time & money to fix this. I think that you're being a bit hyperboleous about throwing in the towel. You'll get it, don't give up.
 
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Just go to www.vintagehondatwins.com and download a Factory Service Manual for your bike. Access to the library there is free with the free membership. They're a little strict with membership approvals, let them know what bike you have and you should be ok.
 

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Discussion Starter · #76 ·
You've come this far & spent X amount of time & money to fix this. I think that you're being a bit hyperboleous about throwing in the towel. You'll get it, don't give up.
I know I was being over dramatic for comedic purposes lol.
 

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Discussion Starter · #77 ·
Just go to www.vintagehondatwins.com and download a Factory Service Manual for your bike. Access to the library there is free with the free membership. They're a little strict with membership approvals, let them know what bike you have and you should be ok.
I signed up yesterday actually and was approved just a little bit ago. That was my next step. Thanks again everyone. I will be back on when I have it figured out or if I have any questions.
 

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Discussion Starter · #79 ·
Well as I was waiting for the other person to come in On that other forum I was testing more and more. First thing I was hoping would fix it. The grounds I had were clean but some of them got a clear coat on it and the bolts I was using as well. When I poked the bolt with the multi meter it went through that top coat. So now all grounds are properly grounded.

Still no spark.

Rechecked continuity of wiring system. The white and the blue wires coming from the stator have ground. That's fine. But voltage output is only 3 volts each.

Now correct me if I'm wrong but shouldn't one wire have 200+ volts and the other 12 volts?
 

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Now correct me if I'm wrong but shouldn't one wire have 200+ volts and the other 12 volts?
I would assume you should be getting more than 100v from both the white and blue.. There are no voltage specs for 80s Honda as testing up til the 90s relied on resistance readings of windings..

Only way to read correct exciter output voltage is if you have a DMM/DVM that is connected to a Peak Voltage Adapter..

Jaw Font Parallel Paper Art


Font Parallel Paper Paper product Document


Suggest you read up on Peak Voltage Testing..
Here is a place to start: https://www.go2marine.com/Product-Guides/MFR/CDI/2-dva-explained.pdf
 
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