New Member, Great site, Please help

[JoeDvlDog]

Thanks for looking. Riding weather is right around the corner so I'm out in the garage getting my bike ready and now I am having a problem with my #2 sparkplug only firing when I let off the starter button. The other 3 plugs fire just fine. Ran fine when I put it up. It's a 1980 GS850L. I've looked through the searches and did'nt find anything simular. Any help would be appreciated, Thank You

[mark]

Does your battery have a good charge on it? What condition is it in? That's the first thing. Your 850 needs a good battery.

A little more info. would help as well. Does the bike start? After it starts does it continue to only run on 3 cylinders?

[DickV]

Ignition problems

I have a 1982 GS450TXZ, two cylinders, two coils - one for each plug. I had the same situation, ie. I got a spark only when I released the start button. It would happen intermittantly on both plugs and the engine would not run. I finally took the coils to a local dealer who used a coil tester to determine both coils were bad. New OEM coils solved the problem and it runs great now.
I believe you have two coils. If a coil were bad I don't know why you would get this situation for only one cylinder, I would think it should occur on the two cylinders that use the suspect coil. After my experience I would still recommend the coil be tested because it seems both the signal generator and the ignitor must be working on your bike.
In any case, I firmly believe in having coils checked with a coil checker so they are tested under load. The spark can be tested at increasing gaps to make sure the secondary insulation is not leaking when the high voltage occurs. Resistance checks on the secondary windings do not tell a complete story.
Good luck,
DickV

[Redman]

Joe,

Having coils tested sounds like a good idea.

Other thing to concider is condition of battery, as Mark suggest. Maybe while running the starter the battery voltage is being dropped down (because battery is marginal), and then when you let off the starter then the batery voltage returns back to normal and then ignition works better.

Sometimes the first clue to a battery (or charging system) problem is that the engine doesnt start as soon as you expect and you let off the starter and then the engine starts imeadialty upon letting off the starter.

You didnt say anything about what you did with the battery over the winter. Something you can do now to somewhat recondition the battery is too leave on the headlight for 15-20 minutes to run it down some (but not flat dead) then charge back up with a trickle charger or battery tender (like 3/4 amp, not automotive 6amp charger) for several hours. Some people think that isnt a good idea, but it has worked for me.

Welcome to GSR.
Okay, now a few GSR members have helped you.
The required fee is for you to post a picture of a GS.
har har just jokeing

Where you located?
Get that bike running and Look at the meeting place section to find a rally near you this season.

[MelodicMetalGod]

Maybe I'm oversimplifying, but all else being equal, the first thing that I would consider and test is the condition of the plug itself and the wire it's on. Since you have three plugs that are working, it's a very simple matter to take the known good components and swap them for the suspect items (one at a time, of course). At the very least, you'll verify the worthiness of those components and eliminate them as the cause. At best, you may find the problem or part of it.

PS: I don't really suspect the plug, but I always like to start out with the easiest and fastest testing/troubleshooting...just in case.

PSS: I also would recommend ensuring the battery is up to snuff, but that's something that should be maintained regardless of a specific issue. Again, it may not be the issue, but ensuring it's to spec will at least eliminate it as part of the problem.

[bradleymaynar]

My vote is on the battery. K.I.S.S. Keep It Simple Stupid (not a slant at you ). What may be happening is that as soon as you let off the starter, the voltage increases enough to the coils. And while Dick says that a dealer helped out him, you've got to remember that a dealership is likely to opt you to the most expensive fix (no offense Dick).

I'd say get a new battery and charge it according to the directions. If it doesn't solve your problem follow the next logical step. This checking the plugs. You may even have a problem with your plug wires. My thought here is to make a progressive repair, ie, cheapest to most expensive. The most expensive being the coils.

Good Luck!

Brad bt

[chef1366]

So much for anonymity Brad;-)

[madjack57754]

Coil fires 2 plugs. if only one of the 2 is firing I'd also check the plug, cap and wire to the coil