Timing light shows erratic spark.

[Anonymous]

I'm working on my buddy's 1980 GS1000. He had the tank off for painting and fixed an oil leak. But the problem now is that it runs rough. It will have its moments when the beast within comes out but it won't idle or run smoothly. I put the timing light on it to check the timing and I noticed sometimes it will consistently flash and then it will stop flashing and then go on again. Cylinder number four is worse than number one but they both do it. I checked the coil secondary resistance and found it to be 280K, almost 10X too high. When I pulled off the spark plug end caps they were 50K just by themselves. So I replaced these with NGK 5K end caps. Now the total resistance of both secondary coils is 20K. The book says it should be 30-33K ohms. Is this a problem? The changing of the end caps gave it better spark when it does fire but it still has times when it should fire and doesn't. It would seem that the primary of the coil or the ignition system itself is at fault. But with the intermittent nature of the problem, what do I look at? It would seem that the recommended check of the ignition (at least in the Haymes manual) would not find an intermittent problem like this. Any Ideas?

Oh, one more thing, when it does run, it will run poorly then backfire then run better.
Thanks in advance,
Steve in Oklahoma. This is my first post. sorry if it's not kosher.

[Anonymous]

Do cylinders 2&3 exhibit the same symptoms? Try swapping coils to see if the the fault follows. If so, replace the coil. If not, you could have a bad pointset or condensor.

[focus frenzy]

80 model has electronic ignition, if the problem does not follow when the coils are swapped, the pick up coils should be checked and if they check out ok then that leaves the igniter box.

[saaz]

Did the problem commence after the tank was taken off and put back on? If so carefully check ignition connections, barred wires etc. Something may have been disturbed. Also possible that an ignition wire was busted, so may give intermittent performance. Could be just coincidence too....just a matter of deduction and testing one possibility at a time to eliminate probelsm.

Good luck!

[Anonymous]

Erratic spark

The problem exists on both coils, on all four cylinders. I noticed that number four was much worse than number one or number three. Then I remembered that I had swapped in an older plug. Replacing that with a newer plug improved it but it did not go away. So maybe that is a clue. Old plug is much more erratic, longer gaps where it does not fire.

I did the pickup coil resistance check and it was fine, around 300 ohms.
When I went on to the ignition amplifier check, placing the ohm meter leads on the connector pins, I did get fire on both plugs (though not before removing the old plug). Though with the erratic nature of the problem, I don't think you would see it with this test since touching the leads is not a solid on/off switch where you would see if you missed a spark since you tend to get several at a time.

Also I would not rule out that both coils are flaky, though they did ohm out.

Any ideas which wires to double check? Power to the pickup? the coils? the transistor unit? I've had the tank on and off so many times, I'm about ready to put a spring on it.
Thanks for all the help.
Steve in OK.

[Anonymous]

The stock coils on my '79 GS1000 checked out fine on the meter, but my misfires were only completely cured when i replaced them with Dynas, with Taylor leads. I know it's been said a thousand times before, but these things are well worth your money.

[Anonymous]

Swapping out coils.

Since coils are a bit steep to be swapping in new ones just to see if that fixes the problem, could I take the coils off of my bike ( a 81 GS650L that runs fine) and try them on the 80 GS1000L instead of spending bucks to find that the coils weren't the problem after all? Does anybody know if those are the same coils?

Thanks in advance,
Steve in OK

[Anonymous]

Re: Swapping out coils.

Does anybody know if those are the same coils?

Shouldn't be a problem. Both bikes have the electronic ignition.

[Anonymous]

I am having the same problem, but only on one coil, tried a different ignitor, but it is still erratic.
Switched coils, same thing, so coils and ignitor, by tests and swaps show good....
How do i check the pick ups? My book has tests for everything BUT that....

[Anonymous]

nevermind, I found the test, pickups show good, fug it, gonna wait 3 weeks and buy the dyna3 kit...... as my used ignitor did not show good after all.

[SqDancerLynn1]

Check and make sure you have 12v going to the ign system.

[earlfor]

I had the same symptoms on my 1150. The bike would at times, for a split second seem that the ignition had been turned off. I never could find anything wrong in my checking of components. Finally, on a ride one day, it quit dead. The problem turned out to be the ignitor box was cutting in and out and ultimately failed completely. I believe your problem is an early sign of a dying ignitor box.

Earl