Alright you GS mechanical geniuses

[onchiman]

Just a thought, I once had a fuse go bad. It didn't blow but vibration caused the element to become disconnected from the ends inside the glass. The bike would start and run fine for a while then suddenly die. Then after a few minutes it would start again. I would check those fuses or jump past the ignition fuse and see if that might be the culprit. Worth a try and it's easy.

[t3rmin]

Have you done the test where you hook a multimeter (or 1.5v battery) up and trigger the spark with the leads? How about the resistance test on the signal generator?

[jimcor]

Just a thought, I once had a fuse go bad. It didn't blow but vibration caused the element to become disconnected from the ends inside the glass. The bike would start and run fine for a while then suddenly die. Then after a few minutes it would start again. I would check those fuses or jump past the ignition fuse and see if that might be the culprit. Worth a try and it's easy.

Usually this is caused by heat rather than vibration. Those little glass buggers get hot enough to melt the solder at the contact ends. Heat caused by resistance from bad connections. Check and clean the contacts in the fuse box to start. And you might replace those old fuses just for good luck.

[Nessism]

What I don't understand is, that if it's a heat issue, I can plug in either of my two ignitor's when the bike is misbehaving, and neither work, but when it's cold, both work. This and the fact that both have the same thing happened when the bike starts and warms up. I will test, but don't think both ignitors are bad.

You have already proved that the ignitor is okay, next check the magnetic pick-up coils on the crank.

[rustybronco]

Well you can take the cover off and get some component cooler from an electronic supply (radio shack) and spray the pick up coils to cool them off when it quits then see if it will fire up, or just substitute parts then try to start it.

[West]

Where'dya get the new coils? Are you absolutely sure thay are not CDI coils? I replaced my coils with CDI coils in ignorance, and the bike started fine, would run for 5-10 minutes & die. It would not start up again until it had cooled of for 20 minutes. Eventually I figgered it out & bought some OLD coils - non CDI. Problem solved.

Whoops - now I see you have ignitors - that means CDI. OK, you sure you don't have point style coils?

Either way, you are going to get a weak spark when things warm up.

How hot do the coils get?

[DrDoot]

The ignition coils were warm at most, not hot. I will take a look at the pick-up coils sometime today. I didn't see anything about them in the Haynes, but I didn't look real hard.

[Jethro]

So you are saying that once the bike cools, it starts up just fine again? Sounds to me you have more of a problem then just the coils, and I'll tell you why. It is very, very rare for both coils to go bad at the same time, and the bike can and will start on two cyls if one coil is dead. I had a problem like this a while ago, and it turned out to be a melted connection in the harness.

Here is what I would do. Get yourslef a multi-meter and go to town. Check voltage at the coils (orange/white wire) with the bike not running and the ignition on. You should have not much less than 12 volts. Take off the headlight and the tail cowl and test the voltage to the headlight and the tail light. Check voltage at the igniton switch itself, and the bar switch.

Basically what my bike was doing was the connector for the starter button was half fried and was shorting out. After a few minutes the heat would get to it and short it out completely. Might not be your problem, but a good sit down with the electrical harness is good to do anyway.

[DrDoot]

Is there a specific spot that I should start looking? I mean it's not a complete electrical failure when the bike gets hot, it just stops running(starter motor will still turn, just no spark from the plugs). I don't see why a short in the taillight wires(which are working) would cause the engine not to run.

Also, if checking the magnetic pickup coils on the crank, what am I looking for/testing?

[DrDoot]

..Anybody?

[DrDoot]

Alright, after taking a couple of weeks off, doing some head shaking, and giving some mean looks on the way in and out everyday, I went after the bike again today.

I can't get it to start period, which didn't surprise me as the battery doesn't normally last long. So I jumped it (with a non-running car battery) and couldn't get it to go either.

Switching the igniters again however, did get me one(yes one) spark. I could get one grumble out of the motor every five or ten minutes or so if I let the bike rest in between. The other ignitor wasn't even giving me that much.

I'm thinking both ignitors are bad, one slightly more than the other?

Where can a guy get a cheap igniter for an '85 GS550?

[bonanzadave]

I asked a question in another thread about Accel coils and the difference between CDI and inductive (non-CDI) coils. West asked the question about your coils type in this thread. Jethro states if theres voltage at the coil + terminal with the key on then you need non-CDI (3ohm) coils. If there is no voltage at the + terminal then you need CDI coils (.7ohms). Go to the Accel web site and check out how to determine the difference between CDI & Inductive (non CDI) systems. Ya got to have the right coils before its gonna work. Good Luck, Dave.

[t3rmin]

Don't waste your time and money with ignitors and the stock ignition -- get a Dyna S! Only $120 at www.z1enterprises.com if you keep your stock coils. Then you can eliminate the guesswork of dealing with 25yr old ignition parts and technology. It was the best $120 I spent on my bike, hands-down. Easy install, too.

[DrDoot]

Definitely considering aftermarket ignition now. I haven't spent much on the bike and I don't think it'll be worth much when it comes time to sell so I've been reluctant, but if it gets it running again I might have to.

As far as the coils question, I have no doubt that they are right because I've ridden the bike for the past year and a half on the same ones and never had a problem until this one developed(not starting when hot).

Thanks for the help.

My only other question is about the magnetic coils. Somebody suggested that that would be my next thing to check. Does the spark for the plugs come straight from the battery (battery--igniter--coils--plug) or does it go (battery--starter motor--magnetic coils--igniter--coils--plug)? Or am I all mixed up?

I just want to make sure that the aftermarket ignition will for sure get spark to the plugs and get the bike going again.

[DrDoot]

I also couldn't find Dyna S ignitions for an '85 GS550 on the z1enterprises site, is there another source?