81 GS550: Bike starts and runs on choke only

[Hobbes]

Hello all,

I know that the admins discourage posting of already covered topics but I haven't found one that is a 100% match up to my situation.

Now onto the problem. I dumped my bike over two years ago and I Just got it running earlier this spring but it would die when I let the clutch out. Then shortly after that I discovered that the bike would only run with the choke on. Well over the summer I dipped the carbs, all but one were in for several hours while the other one was only in for a couple hours. I reassembled them as per the carb cleanup series on this website. Well I can still only get the bike to run on choke. If I add any throttle the bike will bog down and eventually die. If I take it off of choke it will eventually die. Sometimes under choke it will die evenutally too. I'm at a loss for what to do. I cleaned the carbs. I replaced the float needle seat o-rings, the float bowl gaskets, and the air screw needle o-rings on all four. I put the airbox back on as well was the cleaner but no foam is on as the old one was soaked in oil and there was oil in the aircleaner box from a clogged snorkel line leading out of the airbox. I sprayed wd-40 on the intake boots and it had no perceivable effect, the tach cable is broken. I took the petcock off the tank and there weren't any obstructions on the screen. Any help would be greatly appreciated.

[Mikeyc]

Fairly new myself, but.....

Firstly, I am sure you are going to get lots of excellent responses from the Senior Members. I would go to BikeBandit and buy a new petcock. They go bad and IMHO it's not worth playing around with. Next, I would go back through the carb cleaning papers and make sure you did everything right. Most likely you will need to pull the carbs back off and pull the intake boots. I would just plan on replacing the boots and o-rings. I took a short cut with mine because I could not get some of my boots off to save my life. You are going to need an impact driver unless yours have been off and the phillips heads replaced with hex heads. Then you will need to address the airbox issues.

I did 95% of the above (plus colortuning and synching) and my bike is running near perfect. I am sure you will have a similar result.

Good Luck!

[twr1776]

Unfortunately it sounds to me like your pilot circuit is plugged up since it only runs on choke. The choke circuit is seperate from the pilot circuit. When you cleaned the carbs did you make sure all the little holes in the pilot jets, main jets, and emulsion tubes were clear? Float levels within spec? Vacuum line hooked up and not leaking? As Mikeyc mentions if you are unsure of the petcock it is best to just replace it IMHO. The WD40 on the boots usually does not work to deteck leaks unless they are very bad, if they are original they most likely also need replacing with the O - rings.

[tom203]

It sounds like you did a good carb cleaning- but remember, some folks have had to do it twice-, but if you didn't replace those thirty year old intake o-rings, you probably are a good candidate for intake air leak. Air sneaks by in this area rather than pulling mixture thru idle system jets- you can compensate with choke somewhat, but you're not letting the carbs work right.Go to cycleorings website to see a good pic of an old dried out o-ring.

[chef1366]

If you blow carb cleaner into the two jets on the filter side of the carbs it should spray out the main/pilot jets
If not they are clogged

[Hobbes]

Thanks Chef I will have to give that a try and see how it goes. I have only gotten one intake boot off and it was very pliable and the oring was as pliable as the boot. I haven't been able to get the other boots off as the screws holding them on are stripped. Figures right ? Also does anyone know of a cheap place to get a petcock? What about the Pingel kind? I have looked at Z1 but I am curious if there are others out there.

[ejether]

You are getting too much air and not enough fuel, I think everyone can agree on that.
Pilot Circuit/Jet is the first thing people will say but if you are sure the carbs are clean, then look for too much air coming it. That can be a vacuum leak or a non OEM air intake setup, like missing the foam on the air cleaner.

Since you dumped the bike, the carb boot seals are a good place to check, but it might be worth replacing the air cleaner. Cheap and probably much easier then checking the carb boot seals.

I've been having the same problem with my 82 GS650, since I don't have the stock intake.