Dyna S ignition issues?

[rustynissan]

I own a 1979 GS750LN and I have installed the Dynatek replacement ignition system, Dyna coils, Dyna wires and replaced the resistor plug caps.

I am having an issue where I lose spark to the same set of plugs. It will usually run fine for a little while when I first start it up, but somewhere between 5-15 minutes of riding and it drops 2 cylinders. I have verified this with a timing light, 2 of the plugs (on the same coil) are not getting spark. I am beginning to think there might be an issue with one of the pickups on the Dyna S ignition system. Any suggestions?

[BigD_83]

Are you aware of the testing procedure for the ignitor/coils?

Do you have a shop manual?

[rustynissan]

I do have the FSM for this bike, as well as a Clymer guide. I just replaced the coils and it is exhibiting the exact same behavior as when I had only replaced the points with the Dyna S ignition.

[BigD_83]

So, to back up a bit to understand the background:

when you were running points and the old coils, you would lose spark on cylinders 2/3 (or 1/4?) after 15 minutes of running?

Then, you replaced the points with a Dyna S ignition and Dyna Coils (5 ohm?), and you still get no spark on cylinders 2/3 (or 1/4)?

Did the Dyna S come with an ignitor box as well as the pickups?

[rustynissan]

I cannot remember what the bike was doing before I replaced the points with the Dynatek DS3-2 Electronic Ignition (essentially replaces the points with Hall-effect sensors).

After replacing the points, I was experiencing this behavior of losing two cylinders, so I replaced the ignition coils, plug wires and plug resistor caps. I used the Dynatek DC1-1 coils (3 ohms, as recommended by Dynatek tech support). None of this fixed my issue.

[rustynissan]

Did the Dyna S come with an ignitor box as well as the pickups?

No, just the pickups.

[posplayr]

you should make sure that you have at least 11.5V to the coils. If not them you should probably also do a coil relay mod. Power the entire ignition circuit (coils, dyna) from the relay.

http://www.thegsresources.com/_forum/showthread.php?t=141055&highlight=coil+relay+mod

[BigD_83]

I might have to bow out of this thread and watch for some responses from people with more experience in this area, but the ignitor box could be an issue.

[rustynissan]

you should make sure that you have at least 11.5V to the coils. If not them you should probably also do a coil relay mod. Power the entire ignition circuit (coils, dyna) from the relay.

I am getting close to a 2V drop at the coils. I am considering doing the relay mod anyways, but wouldn't that affect both coils? Why am I only losing one coil?

[chef1366]

Was the ignition bought new?

[posplayr]

I am getting close to a 2V drop at the coils. I am considering doing the relay mod anyways, but wouldn't that affect both coils? Why am I only losing one coil?

It is also dropping the voltage to the Dyna.

[rustynissan]

Was the ignition bought new?

Yes, I bought the DS3-2 brand new.

[rustynissan]

It is also dropping the voltage to the Dyna.

I am still confused why only one set of plugs (2&3, I think) is dropping out. I might try temporarily running a wire directly from the coils to the battery as a way to test this out.

[BigD_83]

I am still confused why only one set of plugs (2&3, I think) is dropping out. I might try temporarily running a wire directly from the coils to the battery as a way to test this out.

If that yields no answers, swap the coils around to see if the problem follows

[sschering]

If it is still the same pickup after the swap call Dynatek 800-928-3962.. I have one that does the same thing.. One pickup fails when it gets hot..

If its under warranty they will replace it.. If not they will swap it out for $80
Someday I'll get around to sending it in for replacement.