'81 650 CSR w/ Dyna III Acting Weird

So, I took my recently acquired '81 650 on its maiden (for me) voyage on Saturday. I have many to thank here for getting me to that point but I'll save that for its own topic.

After riding about 10 minutes to a friend's house and stopping there for a short while, I hit the road again and went another 5 minutes or so when I lost ignition on cylinders 2 and 3. I didn't really know that (I just knew something had gone wrong) until I finally got home and felt the pipes. Today, I confirmed that there was no spark on 2 and 3 while the bike was cold so I started poking around the coil leads and took a cursory glance at the pickup coils. After a while, I suddenly had a spark on all 4 cylinders. I *think* that happened after I opened the ignition timing cover and looked around in there.

So, my question is... Since this appears to be a very old Dyna system, should I be looking into replacing it, either with an updated version or with a used stock ignition setup?

I'm going to try to find a suspicious connection somewhere to account for the mysterious disappearing and reappearing spark, but any other information or advice you folks can provide would be much appreciated.

Thanks,

Barry

Do you have 3.0 ohm coils? The instructions specify 3 ohms or higher. The factory coils were less than 3 ohms.

You could try wiggling wires in that area and see if the problem happens again. The Dyna III should be as reliable as the Dyna S, so if it's working and was just a loose wire, I'd stick with it (assuming you have the correct coils for it).

loudhvx wrote: Do you have 3.0 ohm coils? The instructions specify 3 ohms or higher. The factory coils were less than 3 ohms.

You could try wiggling wires in that area and see if the problem happens again. The Dyna III should be as reliable as the Dyna S, so if it's working and was just a loose wire, I'd stick with it (assuming you have the correct coils for it).

Oh, that's a relief. Thank you. I read some older posts about Dyna III's potentially getting flaky over time but I'd much rather leave it alone. I'll continue searching for a loose connection.

The coils appear to be these Emgos and they look brand new:
www.z1enterprises.com/ignition-coil-4-oh...l-output-suzuki.html

They both measure 4.2 ohms, so that checks out. Is there any compelling reason to change those for something else?

Thanks again,

Barry

Those coils should work fine. However, sometimes when people check for spark they don't realize they must check for spark on both plugs connected to the same coil. If they leave one end open so that it can't spark, that can damage a coil or even the igniter. If the bike is relatively new to you, there's no way to know if the previous owner may have damaged something while testing.

I think one thing you can do is swap some wires around to determine if it's the Dyna III or the coils. I'm not real familiar with the wiring of the Dyna III, but I suspect you can swap the pickup wires and the wires to the coils. If the problem stays on 2-3, then the dyna is the problem.

If you can find a diagram I could probably tell you what to swap. (If you want to go that far into the troubleshooting.)

Well, after pulling the carbs to make final(?) float adjustments and putting them back on - which is such an enjoyable experience with the factory airbox and boots that aren't all that soft - I did a little more investigating and didn't find anything obviously suspicious in the wiring. So, I fired the bike up and it ran great, really really great. I rode it around for a half hour or so and it couldn't have gone better.

THEN... This morning I figured I'd ride it to work and less than 5 minutes into the ride, it started cutting out again. I immediately turned around and headed for home at which point it went back to running perfectly. So it looks like I have one of those annoying problems that refuses to stay around long enough to do any real troubleshooting, but also refuses to go away.

I guess I'll pull the ignition components out and test everything for continuity while I wiggle things around. You know, highly sophisticated diagnostics. The good news is that the wiring is pretty simple.

I would redo the spark plug wire connections at all points. or go ahead & get new. The plug wires may unscrew from the cols. you may need to nip off the ends of the wires as they become oxidized. After riding, I would feel the coils to see if they're getting hot to the touch. they should be warm, not hot. press hard with your fingers. Also, check & lubricate the timing advancer if applicable. not sure what the Dyna III has.

The Dyna III is basically the same as the Dyna S, but the pickup plate on the Dyna III only has the hall sensors. The Dyna S has the coil drivers built into the hall sensor assemblies, but the Dyna III has them inside the remote box.

I'll see if I have any more notes on the Dyna III, as that wiring diagram doesn't show the detail of what wire goes to which pickup.

On the pickup plate:
RED wire is positive voltage supply to the pickups.
WHITE wire is the signal from the front pickup (2-3).
BLACK wire is the signal from the rear pickup (1-4).

The pickup plate itself grounds to the motor case, so it is important to ground the Dyna III box to the engine case, which should also be a ground for the battery.

To test if the Dyna III box/pickups is bad:
Swap the white wire and black wire from the pickup plate at the connectors for the remote box..
Also, swap the black wire and green wire at the coils.

The bike should run fine this way.

If the problem moves to the 1-4 cylinders, then the Dyna III box/pickup is bad (or there is a wiring problem).
If the problem stays on 2-3, then it may be a bad coil (or there is a wiring problem).

A very common wiring problem is the use of the Dyna-supplied clamp-splice device. It's usually a blue plastic thing that connects to a wire by clamping on. Those are notoriously flakey.

Another possible wiring issue is the power to the coils may be flakey, so check the red/yel wire at the coils for voltage.

I recall some users reporting that the timing plate sometimes develops cracks, so check that out closely.

As luck would have it, all 4 cylinders are firing consistently so I can't really do much troubleshooting. I've messed with the wires while it's idling to see if I can cause a misfire but it hasn't happened. The wiring all looks pretty sound anyway.

I emailed Dynatek support to ask if this could just be failing due to age and the guy said: "The Dyna III for this application would have to be at least 20 years of age, so anything could be possible." I'm thinking a Dyna S is in my future.

Have you redone the spark plug wire connections? my bike had an intermittent misfire on & #1 & #2. the spark looked fine to me --- checked in a darkened garage at night. but I redid the connections, which solved the problem.

Hi Martin,

The wires are practically brand new. The previous owner replaced them along with the coils, I'm guessing because he was also dealing with this misfiring problem.

What I will do is swap the coils and wires so if and when it happens again, I can see whether or not the problem stayed on cylinders 2 and 3.

Barry

Okay. I would at least disconnect & check the ends as a just in case. doesn't cost anything.