It's NOT the carbs, it's an Electrical problem...

[mike_of_bbg]

Hi bobiii84,

In the OPs case I'm almost willing to bet money that it's an ignitor or similar ignition issue because it's an instantaneous switch from running great to not running at all, then back again. Your issue sounds a bit more like dirty carbs or air leak issues, which are very common on these older bikes. Having to push start sounds electrical, but it's not really clear from your description if the starter just isn't running, or if you've tried so much to start it that you've run the battery down.

In any case, I see this is your first post so would recommend that you post a "hello" in the GS Owners forum. Add your bike to your sig, your location in the user CP, and post a pic of your bike - that will impress Who knows? Maybe some 5-star member (like BassCliff) will leave you with a special present.

After you've done that, come back and start your own post about the issues you're having. Make sure you give a full history of your bike as you know it to date. Then you can get some individualized attention for dealing with your bike's issues.

Oh, and prime is meant to allow fuel flow without engine vacuum: but that fuel flow is less than on "on" or "res". As named, it's more for priming the carb float bowls when they might be empty, and is best used in 10-20 second bursts when the bike has been sitting for a few days/weeks. You don't want to go riding like that. Common petcock issues are the petcock allowing fuel without vacuum in the "on" position and fuel leaking through the diaphragm and vacuum hose, which can flood one of the cylinders (#2 in your case). You can easily check for both by disconnecting your hoses and having a look.

Some questions you'll be asked:

Have you adjusted the valves?
Have you cleaned the carbs (no, REALLY cleaned - disassembled, overnight soak in dip, and re-assembled with new o-rings)?
What shape are your intake boots in?
Have you changed your intake boot o-rings?
Is your airbox completely/properly sealed? (are you running the stock airbox or pods - if the latter are you sure the bike is properly jetted?)

I've been reading through your forum and I'm having similar problems. I have a 1980 GS550L that I recently picked up from a family member. The bike seemed to run fine when I first got it but when I moved it on my truck it started having issues. I had it out in a parking lot teaching my friend to ride when he stalled it and I couldn't get it restarted. I eventually got it started by push-starting it (tough on level ground btw) After I got it started I had to keep on the throttle because it didn't want to stay running once it started up. I got it home and let it cool, when I got home it started right up! Once it warmed up I cut the engine and tried to restart and it just cranked. My Grandfather seems to think it's the fuel petcock being fickle but I ran some tests and disagree. First I installed a fuel shut-off valve and cut it off before shutting off the bike. Still just cranked and wouldn't start. Then I took off and dismantled the fuel petcock. Seems fine to me although there is only a tiny pinhole that changes from "on" to "prime" and I was under the impression that prime just dumped fuel in even with no suction. Tommorow I'm going to take it out and see if it just dies on me while riding but I'm very interested to see how this works out. I hope you figure this out but if I find something I will let you know. Good luck!

[old_chopper]

Colorado,
Make sure you have the correct coils. It's possible you have the wrong resistance coils and they are overheating. I'm not sure they would be so consistent but it's one more thing to check.
No particular reason to check #3 and #4 instead of #1 and #2 plugs, either set will check both coils for fire.
One more idea for a quick check would be to run a wire directly to the positive side of the coils from the positive side of the battery and do a test run. If it doesn't die then your problem is in the wiring and or switches.
Good luck!

[rustybronco]

And why 3 & 4 plugs.....why not 1 & 2?

The reason I stated 3 & 4 was, that is the side the signal generator and ignitor(<??) are on. most likely when you are checking the ignition system your butt is sitting on that side also.

I'm old and I don't need to jump side to side, if I don't have to...

[Sandy]

Here's something to try. As mentioned it sure sounds like the ignitor. If it was a coil or pickup it would mostly likely only affect either your #2&3 or #1&4 cylinders but not all cylinders. The common thing here is the ignitor, a bad connection or switch. Because the symptom is so easily and reliably repeatable I would suspect the ignitor is having a problem. An easy way to tell would be to run it the 10 minutes until it fails and find a way to quickly cool the ignitor. You can use compressed air, canned air, electrical refrigerant or even mist some water on it (being careful about connectors etc). Then wait say 5 minutes instead of the usual 20 - 30 minutes and see if it starts. If it does then that's your problem. Good luck, these electrical gremlins can be a real PITA sometimes. Also if you have the glass tube fuses, replace it, I've seen where they become deattached at one end from vibration and cause weird intermittent problems. They look OK but sometimes work and sometimes not.

[salty_monk]

I've had that fuse problem Sandy talks about. Bike just quit. Was the main fuse.

I also have had ignitir problems so I would also bet on that too.

Dyna 2000 would prob work for you but it's pricey!

[Colorado85gs550]

so here's a NOOB question from a guy that has completely dismantled this frame and cut/welded it into something else:

Where is the ignitor located and where is the connector for it so I can hook up my multi tester and see what I get?

[Colorado85gs550]

Dynatek doesn't list my bike for the Dyna 2000..............

[mike_of_bbg]

I believe the ignitor on 83+ GS550s is under the left side cover.

As issue is that on 83+ GSes the advance curve is built into the ignitor. Any solution needs to take that into account. If Dyna 2000 is not available for your bike and your ignitor is bad, then your options are about down to:

1) Get a used ignitor: maybe your cheapest option, but also poses risk of another "marginal" ignitor - they're all getting old you know.

2) Get a new ignitor - they are available. Very low risk, but very high cost (~$400, but that's about the same as the Dyna 2k)

3) Contact Boyer Bransden and see if they have a product for your bike - and what else you may need (coils, etc.) to make it work.

4) Retrofit a mechanical advance unit and use some sort of non-advance ignitor equivalent. As noted you may need to mod the advance unit to fit onto your system. You could then use Dyna S - you may also need to modify that to fit as well due to 2-point mounting instead of 3-point mounting. Keep in mind that the advance curve won't necessarily match stock, as the mechanical advance tops out at 2.5kRPM.

A few links for your perusal:

http://cgi.ebay.com/ebaymotors/1980-SUZUKI-GS550-L-MECHANICAL-ADVANCE-ALL-GOOD-_W0QQcmdZViewItemQQhashZitem35a7063b5dQQitemZ230435470173QQptZMotorcyclesQ5fPartsQ5fAccessories

http://www.thegsresources.com/_forum/showthread.php?t=105079&highlight=dyna+TSCC

http://www.thegsresources.com/_forum/showthread.php?t=122723&highlight=dyna+TSCC

[Colorado85gs550]

I already have the Dynatek Green 3 ohms coils and 7mm wires. I now have new NGK D9EA Plugs. I'm heading to the local junk yard Tuesday now to get a used ignitor to put in the bike and see if it fixes the problem. I'll be able to get the ignitor for free basicly so if it fixes the problem I'll look into retrofitting a mechanical advance into my motor so that I can save my pennies and maybe sell one of my kids to purchase the Dyna 2000 system to compliment my coils

I'll know by Tuesday night if I've fixed the problem. Can you guys recommend what kind of SillyCone to use when I replace this engine cover? I'm thinking I'm going to have it on/off a few times...........

[Colorado85gs550]

Here's something to try. As mentioned it sure sounds like the ignitor. If it was a coil or pickup it would mostly likely only affect either your #2&3 or #1&4 cylinders but not all cylinders. The common thing here is the ignitor, a bad connection or switch. Because the symptom is so easily and reliably repeatable I would suspect the ignitor is having a problem. An easy way to tell would be to run it the 10 minutes until it fails and find a way to quickly cool the ignitor. You can use compressed air, canned air, electrical refrigerant or even mist some water on it (being careful about connectors etc). Then wait say 5 minutes instead of the usual 20 - 30 minutes and see if it starts. If it does then that's your problem. Good luck, these electrical gremlins can be a real PITA sometimes. Also if you have the glass tube fuses, replace it, I've seen where they become deattached at one end from vibration and cause weird intermittent problems. They look OK but sometimes work and sometimes not.

So should I cool the Igniter box or the signal generator behind the engine cover?

[Sandy]

So should I cool the Igniter box or the signal generator behind the engine cover?

I'd try the igniter first, if it was just a single signal generator failing you would just lose 1 coil and thus 2 cylinders, not a complete shutdown of all 4.