Post by JR on Mar 7, 2014 12:59:13 GMT -6
Sir it doesn't matter about what you are measuring from the output of the CDI to the coil, with a standard mulit-meter it is inaccurate period. The speed at which the voltage discharges is so fast a standard volt meter will not read it fast enough thus the steady drop in your readings. The CDI fires at and incredibly fast pace, it fires twice per revolution of the flywheel, just imagine how many times that is at just a 2000 rpm idle of the engine.
Even ohming a CDI is very inaccurate, best solution? if you think it's the CDI it's a $20 replacement and worst that can happen is you have an extra on hand. If you're getting a steady 80 volts (AC) from the red/black then it's not the stator coil. You haven't mentioned checking the trigger (pulse coil) usually the blue/white or blue/yellow wire? It should read from 0.05 Vac to 1.5 Vac, if it isn't sending a signal no spark.
I also belong to that forum you linked to and if you read the post you'll see he said what you've been told here:
Check the trigger coil and see what it is reading and you also didn't answer my question actually two of them, are you measuring 80 AC or DC and have you left the volt meter on the red/black wire and turned the engine over for a good spell and seeing if the voltage is steady and not dropping there?
JR
Even ohming a CDI is very inaccurate, best solution? if you think it's the CDI it's a $20 replacement and worst that can happen is you have an extra on hand. If you're getting a steady 80 volts (AC) from the red/black then it's not the stator coil. You haven't mentioned checking the trigger (pulse coil) usually the blue/white or blue/yellow wire? It should read from 0.05 Vac to 1.5 Vac, if it isn't sending a signal no spark.
I also belong to that forum you linked to and if you read the post you'll see he said what you've been told here:
There is no 12 volt *ANYTHING* in your ignition system. The spark come from the CDI. The CDI is powered off a high voltage AC winding on your stator. The CDI is triggered by another lower voltage AC winding on the stator. Then somebody tells you you should have 12 volts at the coil, and then you measure 12 volts. This has me a little worried.
Below is what the voltage should be on your igntion coil. There are actually two different waveforms because I have two different brand CDI's. Both work fine. CDI's should be considered black boxes that take in the stator high voltage AC, the trigger pulse. the kill switch connection, and then produce an energy pulse that will couple through the ignition coil to fire the plug. There are many, many ways to do this. I think these two examples show how bizzare the differences in designs can be. So what what would your meter show for these waveforms? I have no idea. It depends on how the meter is designed inside. Different meters will read differently.
The following was measured with an oscilloscope at engine idle. At cranking speeds the waveforms would be the same except the amplitude would be smaller, and the time between pulses would be longer. An oscilloscope is just a fancy voltmeter that is able to measure very fast moving voltages and plot them graphically over time. The horizontal axis is time, the vertical axis is voltage: Use the horizontal scroll bar to see the detail on the right of the graph.
Read more: forums.atvrideronline.com/70/7757269/atv-repair-maintenance/my-atv-chinese-made-4-wheeler-will-not-start/page3.html#ixzz2vIx5xpFH
Below is what the voltage should be on your igntion coil. There are actually two different waveforms because I have two different brand CDI's. Both work fine. CDI's should be considered black boxes that take in the stator high voltage AC, the trigger pulse. the kill switch connection, and then produce an energy pulse that will couple through the ignition coil to fire the plug. There are many, many ways to do this. I think these two examples show how bizzare the differences in designs can be. So what what would your meter show for these waveforms? I have no idea. It depends on how the meter is designed inside. Different meters will read differently.
The following was measured with an oscilloscope at engine idle. At cranking speeds the waveforms would be the same except the amplitude would be smaller, and the time between pulses would be longer. An oscilloscope is just a fancy voltmeter that is able to measure very fast moving voltages and plot them graphically over time. The horizontal axis is time, the vertical axis is voltage: Use the horizontal scroll bar to see the detail on the right of the graph.
Read more: forums.atvrideronline.com/70/7757269/atv-repair-maintenance/my-atv-chinese-made-4-wheeler-will-not-start/page3.html#ixzz2vIx5xpFH
Check the trigger coil and see what it is reading and you also didn't answer my question actually two of them, are you measuring 80 AC or DC and have you left the volt meter on the red/black wire and turned the engine over for a good spell and seeing if the voltage is steady and not dropping there?
JR
..BAD TO THE BONE..
