Pick up coil issue?

[shopteach]

I took my 1979 XS1100 to a shop because I couldn't figure out what was going on. The shop changed the plugs, went through the carb and it ran awesome when I picked it up. I started the bike again when I got back home. seemed like it ran good. I started it up a couple days later and barley ran. Like it did when I took it to the shop. Cylinders 2&3 weren't firing. I have new green Dyna coils and new coil wires. Coils all have the continuity they are supposed to.

Seems as though I am having a sporadic ignition problem. I tested the pick up coil with an ohm meter at the plug and am getting an OL on the multimeter. I checked continuity as far up the wires as I could go at the pick up coil and back at the plug and I got continuity with all 4 wires. I pulled on the wires and they didn't seem broken. All that leads me to believe the pick up coils are bad. Am I on the right track? Can they work/not work sporadically? I found a set on eBay for $300. Does that seem like a good price? Is there a better place to find them? Is there an aftermarket option? Help please I am sooo frustrated with this.

[Socer4m]

HI, I had same issue and it also drove me nuts until resolved,,,,,,first check each pickup coil for correct ohms before spending big bucks, also the wires from the pickups, then the connections at the CDI box,,,pull off connector and make sure all connections are clean. It most likely is a pickup wire or one of the pickups,,, I saw you jiggled the pickup wires just do it while its running and if any missing, that is the culprit. Sometimes the miss can be after the engine and pickups and wires are at hot temps because of the expansion of the wires or pickup material. ONe of my bikes it was the pickup wire, the other bike was a intermittant bad pickup. Hope some one else can chime in on the correct readings for the pickups, I forgot, but there is info on the search or google it.....keep us informed and good luck,,,,Mike in S.Diego and Pa.

[Radioguylogs]

As said by Soccer4m, I would get the bike running if your can, and pull on the wires to each pick-up coil. Cylinders 2&3 are triggered by the same pick-up coil. If it misses when you pull on the pick-up wires, you can fix it without replacing the pick-up coils if you have some basic skills. We'll help you if you find that is the cause.

[DEEBS11]

I had pick-up problems with my bike. Ran ok sometimes when it was cold. When the engine got hot it would sometimes misfire. Turned out to be a common broken wire issue. Usually under one of the clamps. When the advance starts to rotate as the rpms build is when it can separate the broken pieces. Mine was an "just off idle" stumble. Here are some photos of diagnostics and repair.

[DEEBS11]

It should also be mentioned the possibility of counterfeit Dyna coil Chinese junk parts as there are a flood of them in the repair market. They are sold by many "reputable" vendors. Here is an example of genuine parts:

[DEEBS11]

And here is how to spot Chinese F*ckery.

[DEEBS11]

Another example of fake stock style Chinese junk. This kind of crap is being installed every day across the entire world from cars to motorcycles to refrigerators to washer/dryers to lawn equipment and everything in between literally ruining normally infinite sustainable machinery. It's a way to destroy the old and force you to buy the new crap (in this particular case motorcycles) that they are forcing down our throats.

[DEEBS11]

Fake Chinese NGK (as well as others) spark plugs are being sold all over the internet. They not only sometimes just stop working but have been known to separate and the metal drops down into your engine and grenades it. There are horror stories all over the internet on many forums about this situation. We who wrench are f*cked.

[DEEBS11]

https://ngk.sr/technical-information/fake-spark-plug/

[DEEBS11]

Don't even get me started on Chinese junk carb parts.

[LoftCol]

Thanks DEEBS11 for the images of the genuine and fake spark plugs, I have never brought spark plugs over the internet always from a motor parts supplier. Now I will check the the ones I have as if it may be the cause of of some misfiring issues, especially as I have checked everything else. Thanks again

[DEEBS11]

Your least likely problem is the plugs. Most likely are the pick-up coil wires.

[shopteach]

I checked the wires, pulled the sheathing all off and pulled on the wires pretty good. There was no "springy" sections in the wires indicating a broken wire. I researched that problem on here and on Youtube because it seemed like a common problem. Here are my wires:

Yesterday I had my bike in the shop with the heat on and I checked for resistance (ohms) with multimeter across all the wires and got nothing. I checked for for continuity in the wires from the plug all the way up to the start of the pick up coils and got continuity in all the wires telling me the wires are not broken. just for giggles I checked for resistance at the plug today in my cold shop and I got 723ohms on one and 732 out of the other. Seems like they are changing due to heat. Does that sound right?


Let me know what you guys think. I sure appreciate the help. I sooo want to have this issue behind me. Thank you for the help.

[shopteach]

Here are my parts, they all seem to be the good ones right?

[DEEBS11]

Your equipment looks legitimate but I'm not sure with the spark plugs. However, testing wires on a cold, non-vibrating bike might give you erroneous results. I suggest putting it all back together and warming up the bike with the cover off. At idle, start pulling at the wires one at a time and see if you get a reaction.

Another question: When did you start to have this issue? What was done just prior to this problem occurring?