dyna coil ?

Hey everyone. Let my first say that I am not terribly experienced with the technical knowledge of electronics. I can run wires and check connections but don't really understand it very well, and can barely turn on my multimeter, let alone read it and interpret the information.

I am having a problem with my coils (i think) The bike starts up without issue when cold and my ride to work ( about 3.5 miles is always uneventful in the chilly morning air. But on the way home (temp is around 50 +) I get about 2 blocks from home and the bike just wants to die. Like out of gas or really bad misfires, but occasionally blips back to regular performance for a second or two.

I'm guessing that I have a coil that is going out, as it seems to only happen once the bike is warmed up ( I've read this is a symptom of a failing coil) I had it running today and all was good until it warmed up... so I just kept it alive for about five minutes by keeping the rpms up. Then took a reading of the temps on my headers and found that cylinders 1 and 4 were both significantly cooler than cylinders 2 and 3 (also a nod to a coil problem) and it definitely felt like it was running on only two cylinders.

So i checked ohms on both coils input - both right at 3.5 ohms (they are dyantek green coils)
but the strange part is that the coil for 2 and 3 (which was running great) gave me no reading at all at the spark plug connectors, and the coil for 1 and 4 (which according to the temps at the headers were not running well if really at all) came back with a reading of 126.9 ohms on the spark plug connectors.

I'm obviously doing something wrong here... Any help would be greatly appreciated..

Oh and the ignition is a dyna S I believe... I put that on about 4 years ago and never had a problem since (although not very many miles... maybe 1000 total). And just installed the wiredgeorge coil mod a few months ago... which didn't give me any problems at all...Don't know if that would affect this problem or not.

Thanks again.

Primary(small wires) side of the coils will read between 1.8 to 3.0 ohms.

Secondary(sparkplug wire ports)side of the coil will read between 10.4K to 15.6K ohms. These ports are wired together, so it makes no difference which is used, as long as the correct coil to sparkplug configuration is followed. You'll probably need to change your meter's settings for higher ranges when testing the sparkplug ports.

The sparkplug caps should read 5K OHMS(5000), any higher, or a reading of infinity means new caps should be ordered. The heat and vibration can cause the resistor to fail, requiring cap replacement. When re-installing the old or new sparkplug caps, cut about ¼” off the sparkplug wires for a new un-corroded connection.

Never run supression sparkplug wires with sparkplug caps containing the 5000 ohm resistor, as now there will be two (2) resistances in the ignition coil’s secondary circuit, causing weak and intermittent spark.


To stress the ignition coils, take a hair dryer, heat the coils and see if the ohm readings change from cold to hot . If they do, it’s time to buy new coils.