1980 Kz550 LTD ignition coil question.

My 1980 Kz550 LTD original coils are TEC ZC006-TR12V. The primary coil measures 2.4 ohms and the secondary measures 12K ohms. One coil failed. I found some coils that I was told were from an early 80s kz650. I don't think they were. They are TEC EW82-TRI. The primary coil measures 2.3 ohms and the secondary measures 22K ohms. The primary resistance measures the same as the original coils but the secondary on the new coils is about double.  I installed them and the bike runs great. I only drove it around the block because I am worried the spark may be too hot with these coils and the bike may overheat. Is this true or would I be fine with these coils? Thanks.

wrote:

My 1980 Kz550 LTD original coils are TEC ZC006-TR12V. The primary coil measures 2.4 ohms and the secondary measures 12K ohms. One coil failed. I found some coils that I was told were from an early 80s kz650. I don't think they were. They are TEC EW82-TRI. The primary coil measures 2.3 ohms and the secondary measures 22K ohms. The primary resistance measures the same as the original coils but the secondary on the new coils is about double.  I installed them and the bike runs great. I only drove it around the block because I am worried the spark may be too hot with these coils and the bike may overheat. Is this true or would I be fine with these coils? Thanks.



The quote is above.  My response is below.  I can't separate my response from the quote section.  -Lou


Nothing to worry about.  As long as the primary is the same, and assuming the used coils are in working order, it will be fine. Just make sure you only have one resistive device (suppression device) in the secondary.  That is either resistor plugs, or resistor caps, or resistor wire (suppression wire).  Using more than one can make for poor running.


 

EDIT: Ok, there is a red line that shows up if I hover over the bottom of the text area.  I have to click on it and type below it to type outside the quote.
 

Thanks for your help. Also all your links on your page help me out a lot. I did find a set of coils that had the same primary and secondary resistance. About 2.6 ohms Primary and 12K ohms secondary. The thing that I don't understand is that the primary shows a polarity, but I thought it was just a coil. When I checked the Primary resistance with the black meter lead on the negative terminal and the red lead on the positive terminal the resistance was 2.6 ohms and when I reversed the leads the resistance was 2.1 ohms. I had the same results for both coils and i'm not sure why. The coils I am talking about are TEC AW82-TRI. 

That is odd, but when measuring such low resistances, it's easy to have measuring errors in the meter.  It could be something as strange as a nearby radio signal coming through the coil and affecting the meter reading.  

To measure coil primaries, I usually inject a small current and have it in series with a precision resistor, whose resistance is is much higher and can be read with better precision, then measure the voltage on that resistor to calculate the actual current, then divide the voltage on the coil by that current.  Yes much more complicated, but it gets maybe another magnitude of precision.

You don't really need to worry about all that...though it would be nice to know that the measurement isn't indicating some fault with the coil.  It is possible that a weak spot in the primary winding has developed a microscopic break that now has carbon or other contaminant making the break act like a diode slightly.  Just keep an eye on it in case the bike bike has stumbles or starts running on two cylinders.  It will likely show up when the coil heats up from use,