just bought an 85 GS550E, bad carb problem

[newgsman]

is there a spring in the "bar" that connects the two carbs?

[niko]

I have these same carbs on my bike and have been through them a lot of times, most of this you probably know but... The screws on top of the carbs are fuel screws, not air screws and such will give more fuel on idle with them completely open as opposed to closed, when I started to adjust them, I started with them 2 turns out from lightly seated and then continue to turn them out in 1/4 turn increments as listen for idle increases. if you can take them completely out there should be springs, washers and orings underneath them, and the screws themselves should be long and have a point at the end. the tube in the carbs should lead from the small holes on the air intake side of the carbs, to small inset jets in the float bowls, to the place where the fuel screws are, and out into the carb throat near the output of the carbs, i'd dip them for 24 hours and then blow these tubes out with compressed air, covering the various inlets and outputs to try and make sure the air makes it everywhere. the dip will destroy rubber parts so make sure to get all of that stuff out. hope this helps... If you had a lot of junk in the carbs the idle circuits are alomost definitely clogged, as they are tiny little passages that get clogged easily, you should definitely break them down and clean them completely, just be really patient and careful taking them apart.

[Danjal]

My carbs have little screen filters on the valves seats just under the floats. You need to take off the bottom of the carbs to get to them, but if you take them apart and cleant hem you'll get to them eventually. They're held in by a tiny screw. I doubt they'd effect your idle though. Have you checked the airbox and filter yet?

[newgsman]

yes i have, the air box had a few "nuts" in there, and yes they were actually nuts, and the filter had been replaced recently, but cleaned the box right out and took the air hose to the filter

[newgsman]

that does alot really. the screws on the top you refer to are fuel screws? i know exactly the ones you refer to with the springs washers and orings, so where are the air screws if any? or is it preset and the carbs are regulated by the fuel?

[newgsman]

can anyone tell me if these carbs have an air adjustment or if the fuel is the only way to regulate the carbs?

[Calvin Blackmore]

can anyone tell me if these carbs have an air adjustment or if the fuel is the only way to regulate the carbs?

go to basscliffs website and download the manual
the air jets are fixed in place and ther is only one size

this should not affect idle

[BassCliff]

can anyone tell me if these carbs have an air adjustment or if the fuel is the only way to regulate the carbs?

Hi,

There are no air screws on the CV style carbs. The screw on top is sometimes referred to as an "mixture screw" and regulates fuel in the idle circuit.


Thank you for your indulgence,

BassCliff

[Calvin Blackmore]

Hi,

There are no air screws on the CV style carbs. The screw on top is sometimes referred to as an "mixture screw" and regulates fuel in the idle circuit.


Thank you for your indulgence,

BassCliff

I have been thinking

did you break the carbs apart and perhaps alter the relationship of the spring mechanism that allows the throttle shafts to be synched?

I otherwise think it is the pick up tube in the float bowls that are gummed up

they are pretty small orifices.....

[MelodicMetalGod]

newgsman,

Welcome!

I've got the same bike and I also had carb issues when I the bike first came to me.

For me, the solution was as follows:

1) Clean the carbs THOROUGHLY. My methods included completely dissassembling the carbs and going through them with spray carb cleaner, soft wire for the tiniest orafices (jets, etc) and compressed air. Pay particular attention to idle circuit and choke circuit as well as all jets. If you don't need safety glasses for this process, you're doin' it wrong. Many folks also use the dip but it was not necessary with my carbs.

2) Replace the o-rings between the intake flanges/boots and the engine. This ensure a proper seal and is one of the most common issues with these bikes.

3) Re-assemble carbs, bench sync and re-install.

4) Replace air filter.

5) Ensure no air leaks from air box to engine.

6) Use idle screw to set basic idle.

7) Use pilot screws (often referred to as mix screws, fuel-air screws, fuel screws, air screws) to fine tune idle mix on each barrell. These are the screws on the top of each carb that are sealed from the factory and require that the sealing plug be drilled out to access the screws.

Be advised that the pilot screws do not meter only air or only fuel but a fuel rich mix of air and fuel. The do this when the butterflies are closed. Their output is meant to supplement, as needed, the same fuel rich mix that has been introduced to the main bore via the bypass ports, thereby providing the mix required for proper idle.

I all else is well and your idle is running low with the idle screw maxed out, then it is possible that the pilot screws are turned in too far. Easiest thing to do with a running bike is to simply adjust these screw 1/2 turn at a time (on all four bores) and observe any idle difference until you get closer to spec idle and then fine tune from there.

Best of luck!

[MacGyver]

I have been thinking

did you break the carbs apart and perhaps alter the relationship of the spring mechanism that allows the throttle shafts to be synched?

I otherwise think it is the pick up tube in the float bowls that are gummed up

they are pretty small orifices.....

+1 on that. Bench sync the carbs to ensure both sides are at a similar starting point. Syncing these carbs is critical to a proper idle set up. A starting point for the idle mixture screws is 2 turns out, perhaps even 2.5.

I would suspect a part or something is missing on the main idle adjustment. The shop manual (BassCliff's site) wants to balance the carbs at 1700 RPM so if you cannot get it above 1000, something may not only be wrong, but missing or in the wrong place. Or perhaps the idle adjustment screw is too short for some obscure or unimaginable reason.

Getting the idle smooth is a bit of an art form on these carbs. I have resorted to using a ColorTune kit to fine tune the idle mixture and I still want to have another go at it as I think I am still a bit rich. I have also found that setting the idle up around 1250 RPM is a bit more stable on this 25 year old bike with 30,000 km on it and who knows what previous owner abuse.

[MelodicMetalGod]

+1 on that. Bench sync the carbs to ensure both sides are at a similar starting point. Syncing these carbs is critical to a proper idle set up. A starting point for the idle mixture screws is 2 turns out, perhaps even 2.5.

I would suspect a part or something is missing on the main idle adjustment. The shop manual (BassCliff's site) wants to balance the carbs at 1700 RPM so if you cannot get it above 1000, something may not only be wrong, but missing or in the wrong place. Or perhaps the idle adjustment screw is too short for some obscure or unimaginable reason.

Getting the idle smooth is a bit of an art form on these carbs. I have resorted to using a ColorTune kit to fine tune the idle mixture and I still want to have another go at it as I think I am still a bit rich. I have also found that setting the idle up around 1250 RPM is a bit more stable on this 25 year old bike with 30,000 km on it and who knows what previous owner abuse.

1700? I believe that it's 1100, +/1 100 RPM.

[mike_of_bbg]

1700? I believe that it's 1100, +/1 100 RPM.

Yeah, my manual says to sync at 1700 for the GS550s. Idle is ~1100.

[Calvin Blackmore]

Yeah, my manual says to sync at 1700 for the GS550s. Idle is ~1100.

insufficient vacuum at the lower RPM to synch I think.

[MelodicMetalGod]

Yeah, my manual says to sync at 1700 for the GS550s. Idle is ~1100.

insufficient vacuum at the lower RPM to synch I think.

Gotcha. I overlooked the qualifier of "balance the carbs at".