550E, WON'T RUN RIGHT. Carburation or ignition.

[Guest]

Hello all. I am a new to the forum. I bought an 83 GS550E for my lady to take up riding on, but I can not get this thing to run, consistantly, for any length of time. I have been into the carbs several times. To make a long story shorter, I have:
Bought a carb stick.
Replaced spark plugs (twice now).
Installed a K&N factory style air cleaner.
Replaced the o-rings on the manifild boots.
Replaced the pilot and main jets.
Cleaned the carbs,
checked the CV diaphrams for pin holes,
Set the floats level,
Replaced the throttle cable and added an inline fuel filter.

And it still will not run for beans, it runs differently every time I fire it up. I have not been able to put 10 miles on this bike since I got it home. So here is where I am at-
The last time I put the carbs back in, it fired right up , but had a little miss. I changed ot the spark plugs (they were black). I balanced the carbs. I took it for a ride. I thought I had finally got it right. It ran as good as any 550 I ever had ridden. When stoping at intersections the Idle would drop to 1000 rpm, steady and smooth. From 20 to 35 mph for about two miles in residential. I took some open road to see how it ran on the top end. It was still weak, falling flat around 5500 rpm and barely climbing over 60 mph. This lasted for about a half mile Then the whole thing started to deteriorate. When letting off the throttle and pulling to a stop the rpms would remain high and slowly came down. I pulled over to the side of the road and stopped. With out even touching the throttle the rpms continued to surge up and down 1000 to 3000. I road another mile back to the house and by that time it wouldn't even stay running without a lot of effort to keep it there. then it died and wouldn't start. What The French toast??

My next step is to put some fresh plugs in it again (i'm guessing they are fouled)and see if it starts up like a new bike again. then see if it deteriorates again. Like I said I've had the carbs out several times I dont think I can do anything else there. Maybe it is a coil or other ignition problem.
Any thoughts?

[tom203]

The 550's tend to have iffy ignitors, but your problem seems to be carb related. Those replaced o-rings at carb boot/ cylinder head interface... You used viton ones not ordinary buna plumbing ones??

[hikermikem]

I'm assuming you've cleaned the carbs correctly by taking them completely apart & dipping them? Not saying you didn't, but when chasing down issues you have to systemically fix things along the way & be confident of your work. You said you replaced the pilots & mains? Were they damaged? Did you use the correct replacement jets sizes? Did you raise the needles? Set the idle screws correctly? Sync the carbs? Petcock operating correctly? Fuel tank clean inside?

Anyway, since you stated you’ve been into the carbs many times I wonder if they haven’t been sorted out correctly from the get-go. If not, they will haunt you…

OK, with that out of the way, you need to lose the in-line fuel filter, as they can be too restrictive. Also, you absolutely have to use the OEM air filter on those models… Aftermarket filters just do not work with those Siamese carbs… I’ve had a couple 550’s with those carbs and they were the most challenging to get & keep running correctly.

Make sure the airbox is sealed like it’s supposed to be & doesn’t have any extra holes put into it. Do you have the rubber “snorkel” that comes out of the top of the box? The fuel/air mixture with those models is very critical & is not tolerant to any changes as a stock set-up.

[chuck hahn]

You may have changed the wires twice, but i had a similar problem on my KZ project sooting up the 1 and 4 plugs..2 and 3 were fine. The timing light told me the 1/4 coil wasnt consistantly firing and would stop for a few seconds and then resume...till of course the pugs fouled. I replaced BOTH coils and the problem has gone away. Not saying this is 100% whats wrong in your situation, but checking the spark pulses with a light while its running is something to try.

[mainiac]

Are your valve clearances all within specs? I was just reading an old thread where a member was having the same issues and that turned out to be the problem. Just a thought.

[OldVet66]

By replacing the jets you have told me that you haven't truly rebuilt your carburetors. They would have cleaned up nicely along with the jets if you had soaked them and the carburetor bodies in carburetor dip for the required 24hrs. You have valves to check or adjust, probably a fuel tank to clean, carburetors to properly rebuild and an electrical system and harness to check and clean before you can even start to have a baseline to work from. The basic maintenance will cure a passel of problems and make it much easier for you to start your project.

[SNKDLUGOS]

How did you know I used those cheap o-rings Tom. I haven't detected any leaks vacuum leaks, but I will get the viton. I figured they might not last long. Thanks. It sounds like the 550 had a few iffy quirks.

[tom203]

I imagine the buna would last many hours- you probably got other issues as others have stated. Apparently these carbs are tricky to get right

[tkent02]

Buna O rings don't last as long as the good ones, but they last a while. That isn't your problem. What other maintenance has been done? Valves as mentioned above? Cam timing correct? Spark advance working? What are you using for intake and exhaust?

What is the history of this machine? Quarter million miles on it or more? Sat for decades? Worked on by a buffoon? Jetted by someone who doesn't know what jets are?