Dyna S Ignition problem: 2 of 4 cylinders firing

Hello, this is my first post here. I have searched these forums as well as others for help, but I have had no luck. My bike is an 81 kz750 with Dyna S ignition and green 3 ohm coils installed by previous owner.

Long story short- riding my bike up a hill last month, I lost power and it started to sound like i was riding a tractor. Pulled over, shut it off, checked plug wires, restarted, and it ran fine again for the rest of the day. Sat for 2 weeks(indoors) because of rain. Next time I started it, it was only running on cylinders 1&4. Checked connections and such. Seemed okay.

Checked voltage coming into coils. Approx 10.5v for 1&4, and 5.5v(and fluctuated) for 2&3. Traced it to one pickup in the Dyna S(voltage would fluctuate upon me touching it).

I got a used one on ebay(the whole plate with both pickups on it), installed it, and it reversed my problem. Now cylinders 2&3 ARE firing, but 1&4 are not. Voltage coming into the coils is now 9.7v at each coil when the other still has pos and neg wires connected. When pos and neg wires are disconnected from both coils, they both measure 11.2v individually.

Am I not getting enough voltage at the coils to provide spark to all cylinders?
The battery was at nearly full charge when testing (12.4v or so).
Thanks in advance.

Not sure if it had anything to do with you problem but on my Z1B I had problems with the green Dyna coils( i say had because i got rid of them due this problem) with the connections ( the little short screws) to the coils.
Once in a while i would loose 2 cylinders due to resistance/bad contact at the screws.
I tried everything, but the problem would always come back,not always the same screws and sometimes it would be fine a a year or so.
I got tired of it and replaced them with "factory type' coils from Jeff.
They work great with my Dyna S and I haven't feel any power loss or difffence in the way the engine is running

If you have low voltage going into your coils it defineatly will not run right. I would check all of your wiring connections. Sounds like a bad connection somewhere. When you turn on the ignition switch you should not see much voltage drop.

Google "Dyna S Troubleshooting" and you'll find a plethora of info on testing the pickups. Or just go to Dyna and download them.

Take some time to go through the electrical and check all the connections. Pull them apart, clean them shiney new and spray them with some contact restorer, then re-assemble. If you take a few hours to do the whole bike, you will see a big difference.

Determine the quality of power to the coils, by the quality of the spark. Pull the plig wire and stick a screwdriver in the cap (use one hand, and dont touch anything else - if you get a shock it wont hutrt you, just make ya jump ), hold it up close to the engine head/case and the spark should jump from the driver blade to the head. Expand the gap while cranking the motor, and the spark should jump at least a cm gap in the air.

Good luck!

So I went through a bunch of connections and cleaned them, and performed wiredgeorge's mod to get more power to the coils. Both coils now have plenty of voltage, but my original problem persists.

With my replacement Dyna S ignition, coils 2&3 fire. But with the Dyna S that was originally on it, coils 1&4 are the only ones that fire.

I'm lost.

Maybe the used pickups are bad on one side, just opposite of your originals?

steell wrote: Maybe the used pickups are bad on one side, just opposite of your originals?

Totally possible, I've seen this.

Just swap over the pickip so that you have a pair that fire. If the problem still exists, then its something else that is the issue.

steell wrote: Maybe the used pickups are bad on one side, just opposite of your originals?

Yes, this was the case! I had thought of this before, but I guess I had too much faith in the ebay purchase. Swapped em earlier and it fired right up! Remind me to thank the guy from ebay that said they were fully functional...

Thanks for the input, everyone.

Here's how I have my dyna right now (hopefully the pic diagram loaded right). Shouldn't the splice (red wire from dyna) be before where the red/yellow couples into the 2 blacks? Thanks.