GY6 250cc no spark please help???
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07-31-2011, 08:21 AM
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GY6 250cc no spark please help???
Have a kart with the gy6 engine and it will not spark. I have burnt up 2 cdis so far and have no idea why! Thinkin it may be the harness but not sure. I have also read that the ac cdi and dc cdi look the same but will not work the same... Any tests to try? I have no idea what the cdi boxes were (ac or dc) 
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07-31-2011, 12:19 PM
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I don't think there are 250cc GY6 engines. Perhaps it is a 150cc engine?
How did you determine that your CDI is burn't up? If smoke and flames came out of it that is one thing, but if you replaced it and it ran for a while then died maybe somethng else is going on.
You are right about AC and DC CDI's looking the same but being compatible. Here is a generic procedure on how to test whether you have a DC CDI or an AC CDI:
Where did you get your replacement CDI's? Were they AC or DC? On a lot of AC CDI designs, if you plug them into a DC wiring harness the CDI burns up instantly when you try to start the quad - often with a bang and shrapnel.
How did you determine that your CDI is burn't up? If smoke and flames came out of it that is one thing, but if you replaced it and it ran for a while then died maybe somethng else is going on.
You are right about AC and DC CDI's looking the same but being compatible. Here is a generic procedure on how to test whether you have a DC CDI or an AC CDI:
The 2 plug 6 wire CDIs come in two different designs. One is powered off 12 volts DC, and the other is powered off a moderately high voltage AC which comes from the stator. Unfortunately there is no reliable way to tell the difference between the two by just looking at them. To be sure you need to use a meter to find out which you have:
1) Unplug the CDI, and turn on the ignition. Do not crank the starter motor. Use a meter to measure the *DC* voltage on the pin labeled "AC ignition power" in the wiring harness to both ground pins in the 4 pin CDI connector. If you measure 12 volts DC then you have a DC powered CDI.
2) If you don't measure 12 volts DC on the ignition power pin, then switch the meter over to measure AC volts on the 200 volt scale. While cranking the starter motor, measure the AC voltage on the "AC Ignition Power" pin to the the Ground pin. You should see 40 to 80 volts AC. If you measure AC voltage when the starter is turning then you have an AC powered CDI.
Using a meter is the only 100% reliable way to figure out if your CDI is AC or DC powered. But there are some clues you can use that are usually (but not always) correct:
A) DC CDIs tend to be a little larger than their AC powered counterpart. This is because the DC powered CDI needs a bunch more circuitry to convert the 12 volts DC to the moderately high voltage supply that all CDIs must have.
B) Most (but not all) DC powered quad ignition systems do not use the kill switch input pin. The CDI connector pin usually has no wire tied to it. AC powered quad ignition systems usually do use the kill switch input pin.
1) Unplug the CDI, and turn on the ignition. Do not crank the starter motor. Use a meter to measure the *DC* voltage on the pin labeled "AC ignition power" in the wiring harness to both ground pins in the 4 pin CDI connector. If you measure 12 volts DC then you have a DC powered CDI.
2) If you don't measure 12 volts DC on the ignition power pin, then switch the meter over to measure AC volts on the 200 volt scale. While cranking the starter motor, measure the AC voltage on the "AC Ignition Power" pin to the the Ground pin. You should see 40 to 80 volts AC. If you measure AC voltage when the starter is turning then you have an AC powered CDI.
Using a meter is the only 100% reliable way to figure out if your CDI is AC or DC powered. But there are some clues you can use that are usually (but not always) correct:
A) DC CDIs tend to be a little larger than their AC powered counterpart. This is because the DC powered CDI needs a bunch more circuitry to convert the 12 volts DC to the moderately high voltage supply that all CDIs must have.
B) Most (but not all) DC powered quad ignition systems do not use the kill switch input pin. The CDI connector pin usually has no wire tied to it. AC powered quad ignition systems usually do use the kill switch input pin.
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07-31-2011, 10:45 PM
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07-31-2011, 10:48 PM
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#5
07-31-2011, 11:50 PM
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So what happened to your original CDI? If you plug it back in I expect you don't get smoke, right? Perhaps it is worth looking at this further with a meter (in case the CDI wasn't your original problem after all)?
I've ordered lots of stuff off ebay and have had good luck, but I know what questions to ask the seller. If I don't get an intelligent knowledgable answer I go to the next seller.
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07-31-2011, 11:54 PM
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