Multiple (Carburetor?) Problems

[chrisptip]

Hi, I have a 1983 GS550L that has given me nothing but trouble. When I got it, I cleaned the carb, put in new spark plugs, new gas, and new float bowl gaskets. However, it still does a few things that I genuinely have no idea how to fix.

• The first problem is that there's a 50/50 chance that it'll leak gas out of the intake side of the carb body. I set the floats to literally as low as they would go and it seemed to fix it for a bit, but then it started to intermittently leak gas again.
• The second problem is that it almost never holds a constant idle. Sometimes it idles too low, sometimes it's buzzing at 4000 rpm, and sometimes it will seem to idle fine until you give it some throttle, and it will just die or just sound like it's struggling and won't go past 2000 rpm.
• The third and kind of least important problem is that it takes forever to start. Something along the lines of multiple five-second cranks. For the most part, this goes away once it warms up, but it might be tied to the rest of the issues.

This is only the third bike I've worked on so I don't have a ton of knowledge. The first two just needed new spark plugs, new gas, and a carb clean, and I thought this one needed the same judging by the description on Facebook Marketplace, but that was not the case. Thank you guys for your help, really any piece of knowledge or advice would be greatly appreciated!
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[chuck hahn]

So i see one problem for sure. You set floats "AS LOW AS THEYLL GO". Well the lower the hts the higher the gas level in the bowls. Conversely the higher the hts the lower fuel levels. You need to set them according to manual specs. And you need to do a good bench sync when rebuilding them. I rebuild carbs and heres a place with tutorials and other resources. You can follow a turtorial or if youd like me to do them just send me a PM. Your choice. Look up NESSISM here for the CV carb oring kit.
Fuel level has much to do with whether the cylinders get too much fuel and theres only so much that will ignite .After that you get symptoms like you describe.

BikeCliff's Website​

 

[chrisptip]

Whoops, my bad, I meant to say that I set them as high as they could go. I also tried to set them to the manual specs and gas was still pouring out of the carbs. I'll look into syncing too, since I was given and old mercury-type syncing tool.

 

[chuck hahn]

How did you clean them? full tear down and dip in carb cleaner? Did you replace orings on the float seats? Clean the float seats very good with carb spray and a Qtip? Float needles also very clean? Observed the needles rise and fall as you move floats up and down? Ensure floats arent tilted and possibly catching on the bowl gaskets? You gotta be thorough and carbs need to be really clean inside. A spray out with carb spray doesnt cut it.

EDIT, floats can stick even if everything else seems fine. Tap with a heavy wrench on the angle iron mounting rail to jiggle them free. Do not tap on the carb body or the bowls.

 

[chuck hahn]

Set the mixture screws at 2 turns out from gently seated. Slowly turn them in and when they want to stop dont force them furter. then count 2 full turns out.

 

[chrisptip]

I tried setting the mixture screws as you described, and I don't have an ultrasonic cleaner so I went through a whole can of carb cleaner spraying through everywhere as best as I could. I took out the jets and cleaned them, I did the old toothpaste qtip trick for the float seats, and plunged the float needle up and down. After looking at the carb diagram, I can see that I'm missing the small filter and O-ring (part numbers 13376-19F00​ and 13374-35C00​ ) that cover the float needle seat, would that make the difference though?

 

[chuck hahn]

The screen stops chunks coming down the fuel line.50/50 on necessity in my opinion. Yes it stops chunks but it wont affect fuel delivery. Missing orings are critical. No orings on the seats fuel just flows past the floats and never gets controlled. PM NESSISM and get a proper cv oring kit. Id replace ever oring on the rack if it was me.
I dont have any screens but someone may chime in with some. How many are missing? Are the metal plugs under the gaskets there? Round metal discs used to block off the access hole used to drill the passages. at the engine side of the carb body.

 

[chrisptip]

I think it's just two screens that are missing, one for each float needle seat. Is the screen independent of the o-ring? At least on the diagram it shows that the screen goes on top of the o-ring, so I don't know if the screen holds it down or if they just happen to be next to eachother.

 

[chuck hahn]

What your seeing on the schematic is the screen and oring. Oring goes in the groove on the seat and screen snaps onto the end of the seat.

 

[Nessism]

You might want to reset. Be sure that your profile allows you to see other people's signatures, then find mine, and read through the Newbie Mistakes thread, and the carb rebuild tutorial. Your carbs may be different, but the basic concept is the same.

Short cuts are long cuts. Do the job right the first time, and profit!

 

[chrisptip]

Thanks, I'll take a look at some of those resources and let you guys know what happens!

 

[oldGSfan]

With Ed and Chuck chiming in, you're in the good hands. One thing I've done with overflowing float needles is to cut a cotton swab (Q-tip) in half, put it in a drill, dab the fuzzy end in Mother's or other polish (Autosol, Smichrome), and give the contact area a good buffing and cleaning, then hit with carb cleaner. If the needle is all stainless and not rubber-tipped, polish and clean that tip. Make sure the fuel coming in is clean, one way or another as well. I have used this method to good effect on overflowing carbs.

 

[chrisptip]

That sounds like a good idea too, I might try that later since the needle has no rubber on it.

 

[Nessism]

Make sure the float needle tang spring is moving. Varnish collects inside the needle, and then the needle gets stuck. Soak in carb cleaner, and make sure the tang is springing up and down easily, before assembly.

 

[chrisptip]

The float needle spring plunges up and down, but I might just soak it anyway since it can't hurt

 

[londonboards]

Take a look at this vid to show you the neddle valve O ring problem.

https://youtu.be/w30qxIEhFmk?si=N0UcKYMkM3iHtt25

 

[Steve]

I have not seen anyone mention it specifically, but if this IS an '83 550L, it should have the BSW two-barrel carbs.

Procedures and o-rings are just a bit different on these.

chrisptip, concerning your "third and kind of least important problem", assuming the carburetion and ignition are in-spec, the most-common cause of hard cold starting is VALVE ADJUSTMENT. Specifically, they are probably a bit tight. Your engine is a 16-valve, so not shims are necessary, but you have more valves to adjust. Since you have the option of setting exact clearances (shims have to go in rather broad steps), shoot for mid-range to maximum clearances.

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