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Dyna S ignition issues?

  • Thread starter Thread starter rustynissan
  • Start date Start date
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rustynissan

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

Do you have a shop manual?
 
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.
 
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?
 
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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.
 
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.
 
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?
 
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.
 
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
 
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.
 
I recall a thread where someone had a similar dropped coil problem that turned out to be an issue of the points or pick-ups reacting to heat or condensation beneath the ignition cover that somehow caused the ignition to fail after a some time riding.

Sorry to be so hazy, but I think they isolated the problem by taking a ride without the points cover, to confirm that was the source of the problem. Not clear on how they ultimately sorted out the actual problem though.

Edit - turns out I am not crazy. http://www.thegsresources.com/_forum/showthread.php?t=166470&highlight=heat+ignition+cover

Bwringer is wise. See if that sounds familiar.
 
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I recall a thread where someone had a similar dropped coil problem that turned out to be an issue of the points or pick-ups reacting to heat or condensation beneath the ignition cover that somehow caused the ignition to fail after a some time riding.

Sorry to be so hazy, but I think they isolated the problem by taking a ride without the points cover, to confirm that was the source of the problem. Not clear on how they ultimately sorted out the actual problem though.

Edit - turns out I am not crazy. http://www.thegsresources.com/_forum/showthread.php?t=166470&highlight=heat+ignition+cover

Bwringer is wise. See if that sounds familiar.

I am having the same problems as bike#2 from that post. I got the "poof" when I turned the bike off on occasion. I also remember riding around with the ignition cover removed once and I had a very enjoyable ride for about 20-30 minutes. Putting the cover back on and riding later that evening (in cooler weather) I was able to go about 10 minutes before losing two cylinders. I will definitely be contacting Dynatek, and will probably do the relay mod anyway.
 
I had the same issue and it was a bad coil at the crank.
Ask for Raymond at Dynatek and tell him Big Bill from Bako sent you. He does all my head work and is a guru.
 
I actually just got off the phone with Larry at Dynatek tech support (they have GREAT customer support, btw!!!) and he gave me a couple things to check out:

1) Check all connections to the coils.
2) Check that both coils are getting proper voltage when it is failing.
3) Check that the ground wire from the back of the engine to the battery post is present.

If all this checks out, I will call them back and arrange for an RMA.
I have already done #1, #2 seems to check out on account of the "poof" upon shutoff (indicating a collapsing field in the coil for one last spark, as bwringer has pointed out), and #3 is really all I have to check.
 
He did not ask you to test the resistance of the two Dyna S coils? With the magnet on the crank trigger facing away from the one being tested put one lead of your multimeter on the power and one to the ground wire. These are the wires that come off the Dyna S and go directly to the coils.
Use the ohm setting on the meter.
Ask Larry or Raymond for the range.
This is how I found out mine was bad. It would run when cold and then cut out one coil when hot.
 
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