GS1100E ignition problems

[metalfab]

I am working on my 1982 GS1100E. At an idle I have lost ignition on cylinders 2 & 4, the pipes are cold. When I rev it up I can hear it intermittently cutting in and out. And the pipes warm a bit. I was looking at the factory wiring diagram and it looks like the pickup coils are wired in series, where one cant fail or it would take out both signals? I am assuming that I have lost good continuity on a coils primary wires, or possibly a coil is bailing. Does anyone know where the wires are routed between the ignition unit and the coils, and are there a lot of plug in connections in between the coil. A couple of years ago when I was on a road trip and I got stuck in the rain it acted up and felt just like this. But it cleared up on its own, after the bike sat 2 days and dried out. This time it acted up just after it sat in the rain 2 days. The rain might be a coincidence.

My questions are is there a common failure that causes these symptoms, where are the primary ignition wires routed, and how many plug in connections are there between the coils and the ignition control unit.

[bonanzadave]

Have you ever changed the spark plug caps ? If not....do it. What is the running (2000rpm) voltage on the battery ? How about the running voltage at the coils ? I did a coil relay mod on mine to get solid battery voltage to the coils.

If you get a rainy day with nothing to do spend some time cleaning all the electrical connections.

[metalfab]

Have you ever changed the spark plug caps ? If not....do it. What is the running (2000rpm) voltage on the battery ? How about the running voltage at the coils ? I did a coil relay mod on mine to get solid battery voltage to the coils.

If you get a rainy day with nothing to do spend some time cleaning all the electrical connections.

I put new NGK plug caps on it about 18 months ago. I was hoping to find out the wire routing and the plug in connector locations. So I could check out the wiring without too much exploring. Since 2 & 4 are failing together I was thinking a coil or its wiring. I know how electrical systems can be. What I think might be far away from the problem, still from the diagram it looks possible.

[JTGS850GL]

I question if this is an electrical issue since plugs 2 and 4 are not related. Plugs 1&4 and 2&3 fire together. I would suspect that you are experiencing a fuel related issue. when what the last time that your carbs have been cleaned? When what the last time your valves have been adjusted?

[metalfab]

Carbs

That is a good catch I haven't dug into it yet. The carbs were cleaned out about 2 years ago, it hasnt had that many miles put on it, but I know all too well how easy it is to restrict the small passages. That could account for the cylinders pulling back in to a degree when it is revved. I am going to pop the tank off in the next few days and dig into it.

[Roger P.]

I am working on my 1982 GS1100E. At an idle I have lost ignition on cylinders 2 & 4, the pipes are cold. When I rev it up I can hear it intermittently cutting in and out. And the pipes warm a bit. I was looking at the factory wiring diagram and it looks like the pickup coils are wired in series, where one cant fail or it would take out both signals? I am assuming that I have lost good continuity on a coils primary wires, or possibly a coil is bailing. Does anyone know where the wires are routed between the ignition unit and the coils, and are there a lot of plug in connections in between the coil. A couple of years ago when I was on a road trip and I got stuck in the rain it acted up and felt just like this. But it cleared up on its own, after the bike sat 2 days and dried out. This time it acted up just after it sat in the rain 2 days. The rain might be a coincidence.

My questions are is there a common failure that causes these symptoms, where are the primary ignition wires routed, and how many plug in connections are there between the coils and the ignition control unit.

Pull the plug on the ignitor and make sure the bullet connector female ends haven't worked themselves slack. My 1100 would lose spark intermittenely. I removed the ignitor from the bike and manipulated it while starting and running and I found the loose connectors. I pinched them tight, cleaned and lubed them and the problems disappeared.

[Brendan W]

First thing I would do is swapover the 1 & 4 ht leads and the 2 & 3 leads and see if the problem moves from 2 and 4 to 1 and 3. If so most likely you have a ht lead and/or plug cap problem which could be water.
At that point run the bike in the dark with the tank off looking for where the sparks are leaking out. It could be that the leads are cracked or that water is running into the plug caps. Most bikes had outer sheaths and rubber boots at the caps to stop that happening but many have lost them over the years.
WD40 or Dampstart could solve it temporarily.

[JTGS850GL]

If the problem is truly on cylinders 2 and 4 counting 1,2,3,4 from left to right while sitting on the bike, then it is not electrical unless you've also messed with which plug each coil plugs onto. Electrically plugs 1&4 and 2&3 are connected. They run in waste spark mode meaning that the two coils fire two cylinders at a time. When you get spark on cylinder 1 you also get fire on cylinder 4. Even if it doesn't need it. Same goes for cylinders 2&3.

If you've verified that the correct plug goes to the correct cylinder and this problem is only at idle, then I'd check for fuel related problems like fuel in the vacuum line on carb number 2. Pull your plugs and see what color they are. No fire on a cylinder could be lean or rich depending on the source of the problem.