Calling on electrical gurus

[CC898]

My bike has some kind of electrical gremlin in it. It has absolutely no spark what so ever. I got a new plug, a got a new plug cap, I changed out the coils with one I know was working, I got a used but good CDI box (old one was showing no resistance or voltage) and still nothing. I checked the stator, that sucker is cranking out power just fine. So the CDI box is getting juice, but wont spit it back out. I checked the new CDI's resistance and it showed the right amount of OHMs but still no voltage. I have it wired correctly for the bike (93 RM250, please don't move this to a make/model specific, its a general question and all bikes can have this issue) green to green, red to red, and double plug female end to male end. I've also got a new kill switch on it, but I took it off to eliminate that as a reason. So what can I do now? I have no idea what to try next. Any help/advise would be greatly appreciated

 

On a side note, this is after a top and bottom end rebuild, so I haven't drowned the bike or caused any reason for things to be screwy, this is just how I got the bike. 

[Dune bum]

Everything you talked about is where I would have started. That said a lot of  my electrical issues in my day have been a simple bad ground, broken wire, hot going to ground somewhere, broken solder joints. It does not take much to mess with an electrical system. I am no expert just some of the problems I have ran into my day just keep hunting you will find the gremlin giving problems.

[mastera210]

Sometimes dam gremlin is hell to find had a KX250 one time at the shop we tested everything and it all tested good! The owner had the same bike so we started swaping parts and it was stator! I know you cant do that and elec parts you cant return so I wish you luck!

[Qqqqqqqqqqqq]

Have you checked the ground's

[poconovfr]

+1 on the grounds.

[CC898]

How would I go about testing the grounds? I'm only able to wrench on this thing on the weekends so excuse any late replies from me. I have checked the soldering points, they seems good. But the grounds issue sounds promising as there is literally no spark, I held the plug in my hand and cranked it over just to be sure. 

[Cincyboy]

I feel your pain. I would clean the areas where any grounds are very thoroughly with sandpaper as a start. You can us some dialectic grease or even Vaseline on those connections. I am thinking ground issues versus anything else since you have checked everything

[CC898]

I didn't have a chance to test the ground this weekend, but I did take a quick look at the coil before I left for college, the small ground piece that is mounted on the coil isn't facing, therefor isn't touching, the frame. Could that be my problem? I didn't have time to re mount it 

[Cincyboy]

That could be your source... Let us know what you find

[CC898]

I'll keep you guys posted. I really hope so, I've spent so much time (and money) on this bike. Its just super frustrating that I can't tinker with it when ever I want, I have to get back home on the weekends. 

[Theeebalz]

+1 on ground, after that i would check your killswitch, and double check your pickup coil, then check your flywheel, could be corroded over on the magnets

[CC898]

I dis connected the kill switch to rule that out, and I sanded the fly wheel magnets just to be sure they were good. I will double check those things when I get back if the ground isn't the issue. 

[CC898]

GOT IT!!! I think. My garage is really bright, so I decided to take a volt meter to it instead of relying on an eye test. Says I've got 20 volts coming out of the coil and cap. Sound about right? I'll be going for a start up tomorrow morning hopefully 

[CC898]

False alarm. I was getting strong current out of it all today and then I put the tank on to test run and still nothing. No spark yet again. But then I tested it with a volt meter. I get current sometimes, but maybe 25% of the time. I have no idea anymore. Maybe I got sold a faulty CDI? I just don't know anymore. Last night I saw bright blue spark. Now nothing. Then something, but then nothing. I checked all the wires, no frays, breaks, exposed wires. No broken solders, everything checked out with the OHM meter according to the manual. I just really think this bike is cursed and maybe I should be consulting a Bible instead of a manual now? 

[roger young]

The Stator on your bike has two coils. one two charge the capacitor in the CDI and one to release the charge to the coil. Typically called the charge and pickup coils in 93. You should be getting a voltage pulse from each coil. The pulse duration is usually milliseconds in length.

You will probably need a peak voltage adapter and the max function of a digital multimeter to read the pulses. Sometimes the resistance of your charge and pickup coils can be within limits but still not work. If you have no bad grounds or opens I would look at the stator.

[LiamRM212]

This happened to me on my old xr80. Gave me so much trouble I sold it for 200. Went out and bought an RM 125. It was a great fix.