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Post by lostforawhile on Oct 11, 2017 23:39:28 GMT -5
Ok I have done everything to get this bike running again, cleaned the carb, changed the CDI out, change the coil out, checked the valves, changed the gas, I have compression, fuel, and spark with a plug outside of the cylinder, but the engine won't fire even once, I have exhausted every explanation i could think of, the only thing left is a weak charge coil on the stator, that is letting the CDI fire the coil, but at a lower voltage. The CDI can only step up the voltage depending on what it's given. I've been having issues where the bike would run great, then suddenly run worth a crap, it would miss, backfire, etc. My plug had been looking good, but when I pulled it this time, it was fouled, probably by a misfire. I replaced the CDI with a factory high quality one, which is the only CDI that will work on this bike, I just replaced the coil with a Suzuki coil and wire, which is very close to the factory one, but much better quality, it fires fine. I've cleaned the carb, and installed a new jet, which I was going to tune, but it never started again, it should be set well enough to at least run, or start. it's like the ignition system took a crap, the only thing left is the stator , I'm getting about 30 volts to the CDI while cranking,which seems low, but will fire a plug
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Post by lostforawhile on Oct 12, 2017 20:26:11 GMT -5
I double checked the valve clearance again,it's fine, getting fuel, ignition working with a grounded plug, timing is right, 110 PSI compression, the only thing left is the charge coil on the stator. 20 volts AC is the minimum, and I'm at 30, so it's really marginal, it's probably not firing under compression. I do remember smelling burning plastic a couple of weeks ago, before all these issues started, so I may have had one of my charge coils failing. it had also stopped starting on the starter sometimes, and had to be kick started ,
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Post by bluegoatwoods on Oct 15, 2017 6:06:46 GMT -5
I can't really be of much help here because we're already in just a bit over my head. While I can understand the issues you've mentioned, I've never diagnosed and repaired most of them.
I've heard of spark plugs that would fire in the open atmosphere, yet refuse under compression. But I'd had the notion that this was caused by some sort of fault in the spark plug. I'm having a hard time seeing just how the system which feeds electricity to the plug could be affected by whether or not the plug is under compression.
But if we discount this, then your no-start situation seems even more mysterious since you've covered the basic air/fuel/spark checks. And it does sound as if you were thorough on that. And I can't think of anything you've missed.
Considering how GY6 components are mostly of pretty mediocre quality, I can picture a stator losing it's magnetism over time. Maybe those particular magnets are made from a cheaper, yet not very good, alloy? This is really nothing more than a guess. But it seems possible.
So maybe you ought to swap our your stator and see if there's any improvement.
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Post by lostforawhile on Oct 15, 2017 9:49:08 GMT -5
It takes a much higher voltage for a spark to jump the gap,through the mixture, under compression, then it does in open air, if I had a scope the problem would have been simple to diagnose, what happens to the stator, is the windings on the high voltage coil,or coils,fail, normally due to heat, and poor insulation, and low quality wire.
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Post by bluegoatwoods on Oct 15, 2017 12:18:45 GMT -5
Okay, I think I see it.
It takes a higher voltage for the spark to jump the gap under compression. The coil, obviously, will multiply the incoming voltage. But if the incoming voltage is low, then the outgoing voltage will be low as well.
If I understand the CDI correctly, then it will have no effect on the intensity of the flow of electrons. It only affects the timing, right?
That would seem to leave only the stator as your culprit. It could certainly deliver a low voltage. And I'm having a hard time imagining anything else in the chain from stator to spark plug that could do it.
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Post by lostforawhile on Oct 15, 2017 14:46:45 GMT -5
Okay, I think I see it.
It takes a higher voltage for the spark to jump the gap under compression. The coil, obviously, will multiply the incoming voltage. But if the incoming voltage is low, then the outgoing voltage will be low as well.
If I understand the CDI correctly, then it will have no effect on the intensity of the flow of electrons. It only affects the timing, right?
That would seem to leave only the stator as your culprit. It could certainly deliver a low voltage. And I'm having a hard time imagining anything else in the chain from stator to spark plug that could do it. the cdi takes the incoming voltage and multiplies it, and charges the capacitor, which discharges with a signal from the pickup. if the incoming stator voltage is low, it affects the output voltage. the minimum at cranking is about 20 volts, and I had 30 so it's marginal, the issue is, at starting there isn't enough voltage being produced to jump the gap under compression. This is most likely why it was refusing to start with the starter, but could be kick started, kick starting spins the engine faster and produces a higher voltage |
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Post by lostforawhile on Oct 15, 2017 15:01:06 GMT -5
en.wikipedia.org/wiki/Paschen%27s_lawthis is a Champion model 800 plug tester, it could clean a plug, plus test it under pressure, the plug screws in the top, into a chamber with a glass window, which is pressurized with compressed air. then a high voltage transformer is attached to see if it sparks. either a bad plug, or a weak voltage at the plug would cause a no spark condition. 
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Post by greginisn on Oct 16, 2017 0:54:40 GMT -5
Another possibility to consider is the ignition timing. There is a woodruff key that holds the "flywheel" in proper position. It could be sheared or partially sheared causing your timing to occur at totally the wrong time. If you have a timing light you could verify your ignition timing without having to take the flywheel off to check the key.
Good luck, Greg
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Post by 90GTVert on Oct 17, 2017 8:12:12 GMT -5
I'd check the key out as Greg described above. You can check the spark a little better with a large gap tester like an HEI tester or an adjustable gap tester... or you can cut off or bend back the ground strap on a plug that you aren't going to use anymore to make the spark jump a larger gap. Usually if they'll jump a big gap all the way to the edge of the plug, you have sufficient spark energy. You can get a stator for $10-$15, so if you're suspicious and can't find anything else it's not too bad to just replace it. Just make sure you compare pics of a new stator to what you have, because there are different configurations of plugs and wires and coils.
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Post by greginisn on Oct 18, 2017 3:20:38 GMT -5
or you can cut off or bend back the ground strap on a plug that you aren't going to use anymore to make the spark jump a larger gap. Usually if they'll jump a big gap all the way to the edge of the plug, you have sufficient spark energy.
Thats a terrific idea. I had never thought about how short the ceramic is on this plug, was used to plugs with an “extended reach” and it would have been quite a challenge for a spark to jump those gaps but this sounds like a great troubleshooting tip.
Thanks again, Greg
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Post by lostforawhile on Oct 19, 2017 11:29:48 GMT -5
Stator got here yesterday. So I'll work on it tomorrow. The first one amazon sent is still touring the US by itself
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Post by lostforawhile on Oct 19, 2017 20:13:03 GMT -5
OK now I have 60 volts from the charge coil, vs 30 before, the old coil also smelled burned, but I have no voltage from the pickup right out of the stator, I already checked the gap and it's right. Apparently the new stator is good but the pickup with it is bad, it's too late to do anymore tonight, so I'll swap out the old pickup into the harness tomorrow,
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