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hi I'm new to the site but have read all the old posts on bayou 220 i have a few questions for you experts. first while spinning the motor over with plug out how much voltage should be coming out of the red wire on the magneto going into the cdi box mine has 17 volts but nothing commimg out going to the coil. HELP
 

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Do not test your CDI by energizing it with the generator side of the motor and then probing the output of the CDI, you will immediately fry the CDI.

Follow the procedures for testing as outlined in the service and repair manual, and use a digital high impedance multimeter to avoid backfeeding current and frying the CDI. Or, if you are like most, just take the CDI, the exciter coil, and the ignition coil to a dealer and have them tested.
 

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The way these work is there is a pulse coil that excites the CDI to create a trigger effect for timing of the spark, and the voltage on that will vary but it is also not a power source but a version of a hall effect switch that generates an AC current to establish lead, peak and lag for timing the CDI. The regulated battery power is the switched power source for the ignition coil, and the CDI is the means to convert the timing pulse to a switched power supply for the ignition coil. The generator, or more factually alternator, is not used to power the CDI directly as it will damage the CDI.

If you run the CDI without a battery you will fry it in short order as the battery functions as a wet capacitor to take the spikes out of the voltage so the regulator will control output within a set range as outlined in the specifications. While the voltage on these is regulated and converted to DC for the switched coil side of the CDI, it is not true DC. It is a pulsed DC that has half the AC pulse whacked off and bled away as heat. That makes it critical to have a good battery in the system to absorb the peaks of the DC current and allow the regulator to do its job.

The only place you want to test DC voltage is on the circuitry after the battery. Anywhere else is a waste of time as it is unregulated and can vary dramatically with engine speed and battery condition.
 
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