GS550ES Carb problems.

[Danjal]

1985 GS550ES
OK, first off I think theres a dyno jet kit in stalled in this bike. So that might be the problem. I just picked up this bike thursday, and the carbs leak while running, right out the intake. More specifics below. If I give it throttle..dies instantly. Im going to safely assume that its getting way too much fuel when I do this and floods the engine. It also idles at 3-4k... depending if the choke is on or not.

The pilot air jets are right on the edge of the carb housing like the ones in this link. (Only on the secondary carb..the primary are a bit further in as bubba got a bit overzealous with the hammer and drove the primary ones in further. The main jets are size 81. Both main jets in both carbs. And the jet needles almost come to a point on all 4.

http://forums.somethingawful.com/showthread.php?threadid=3017242&pagenumber=1#post352764314

I have checked the petcock.. runs as supposed to. I can pull the lines and its not running out the tank untill its on pri. Run and reserve supply fuel to the carbs, but not when its off.

Furthermore... I can set up the carbs out of the bike and they dont leak a drop till they're in there and its turned over for a bit.

Other than the carbs it needs a side stand and a new horn. But even with a little bit of running at an idle of 3-4k its running nice.


Soooo.. Your thoughts on fixing this mess?

[almarconi]

I would remove the carbs, disassemble and clean them. Make a note of all the jets and compare them to stock to see whats actually in there. Dirt stuck in the fuel needle seat will cause your carbs to overflow. Incorrectly set floats or worn fuel needles could also cause this problem. Set your float height according to the manual. Reassemble them, bench sync and then vacuum sync them once they are installed on the bike. High idle could be caused by air leaks, mis adjusted throttle cable, choke mechanism or throttle mechanism out of adjustment. If the PO actually damaged the carbs, depending on what was done to them they may have to be replaced. Not sure why you would drive any carb component into place.

[BassCliff]

Greetings and Salutations!!

Hi Mr. Danjal,

To answer your spec question from another thread, I used the Search Feature in the "carb oem spec as per factory manuels" (sic) thread (a sticky at the top of the Tech Section) and found this. It should be the same as your twin-carb '85.

83 GS550E
Mikuni
BSW30SS
30 mm

It should have 43410 stamped on the side

Fuel level: 6.5 +/- 0.5mm (.26 +/-.02in)
float height: 20.5 +/- 1.0mm (0.81 +/- .04in)
Main jet:
cylinders 1 and 4: 95
cylinders 2 and 3: 102.5
main air jet: 1.0
Jet Needle: 5C64
Clip position: 1 groove from top
needle jet: P-2
Throttle Valve: 120
Pilot Jet: 35
Bypass: 0.8,0.7,0.8,0.8
Pilot outlet: 0.7
Float valve seat: 2.5
starter jet: 55
Pilot screw: Preset

Collected on my website:
On the GS Resources Forum there is a thread containing a collection of carb specs. That thread is located here: CLICK HERE.

Mr. johnnay has collected this information in a handy Excel spreadsheet. Download that spreadsheet here: CLICK HERE.

(Note: If you do not own Microsoft Office, I recommend downloading the free Office-compatible suite from OpenOffice. CLICK HERE.)

I'm glad you found us. There is literally hundreds of years of experience represented in the GS community here. And now, the big prize.....It's my own "welcome thang"...

Here is your very own magical, mystical, mythical, mind-expanding "mega-welcome". Please take notice of the "Top 10 Common Issues", the Carb Rebuild Series, and the Stator Papers. Now let me roll out the welcome mat for you...

Please click here for your mega-welcome, chock full of tips, suggestions, links to vendors, and other information. Then feel free to visit my little BikeCliff website where I've been collecting the wisdom of this generous community. Don't forget, we like pictures! Not you, your bike!

Thanks for joining us. Keep us informed.

Thank you for your indulgence,

BassCliff

[Danjal]

I dont have the stock parts, but according to this thread the parts arent stock anymore. http://forums.somethingawful.com/sho...#post352764314

carbs have been removed and cleaned...twice. Everything seems to work on the bench with the tank hooked up. The fuel needle seat looks fine as does the needle. Floats were set at .81" according to manual. As for vac synch.. its not even in the ball park to be synched. Much less dry enough once it starts running. I'll check the cables on it, but they seem fine.. but its worth a shot. I have no clue why anyone would want to drive in carb parts myself.. Im guessing it was part of the dynojet kit though.

Main jets are both 81. The actual carb numbers are on there somewhere.. covered in black paint. I'll have to get to that tomorrow.

[almarconi]

carbs have been removed and cleaned...twice. Everything seems to work on the bench with the tank hooked up. The fuel needle seat looks fine as does the needle. Floats were set at .81" according to manual.

Sounds like you've got all the bases covered. Glad you got it figured out.

[Danjal]

Its still not working right. I did all that before I posted on here. I seriously think someone botched the dynojet install, or theres something im missing here. Its running way way too rich.

[MelodicMetalGod]

Danjal, sounds like you've got an interesting issue there. I don't know anyting about jet kits as I've always stayed with stock components but my "intuitive" approach to troubleshooting carb issues leads me down the following road.

To clarify, it sounds like you've got three symptoms:

a) High Idle (3-4k RMP) that never settles, regardless of choke
b) Fuel leaking from carb intakes
c) Instant stall upon any throttle input

1st thought is to get the idle settled and with a high idle issue that means ensuring that there are no vacuum leaks. In particular, check the intake boots and o-rings between the enging and carbs and the boots between the air box and carbs. In my thinking, if fuel is leaking from the intakes, if nothing else, that may also indicate that air is finding it's way in.

2nd thought is that if the fuel is leaking out of the intakes and the floats are set to spec then the needle valves are not sealing, indicating something worn to failure in that assembly or possibly a float that doesn't.

3rd thought is that although your carbs are leaking, I'm not sure that necessarily means that your engine is flooding. In fact, the high idle along with the stall under throttle indicates, again, vacuum leak and/or blocked fuel delivery resulting in a lean condition at idle that stalls under throttle as even more air is introduced to an already lean condition.

Aside from the leaking fuel, you seem to have symptoms very similar to what my bike had when it first came to me. The fix? New boots and o-rings on the engine side and a THOROUGH hand cleaning of the carbs.

See my project via the link in my sig.

Also, here's a search that has several excellent threads that may be of help: http://www.thegsresources.com/_forum...archid=1093693

Best of luck!

PS: Also see the link in my sig for the 83-86 GS550 Owners Group

[BassCliff]

Hi,

Here's a little tutorial that I've collected on my website from one of our resident GS850G gurus. But most of this is applicable to most GS bikes. Thanks to Mr. bwringer.

*********Quoted***************

Overflowing Carbs by Mr. bwringer

Let me point out the obvious: If a carb (or carbs) are overflowing when the bike is not running, you have TWO problems. First, your petcock should prevent ANY flow; second, the needle valve should allow flow only up to a fixed height in the bowl (ie, not overflow). Excess fuel has to make its way past both of these parts.

(A third possibility on old carbs is for fuel to flow past the inlet seat O-ring. [n/a for VM]. That doesn't apply to newly rebuilt carbs, since the owner has just installed brand new. Right??)

I'm not 100% sure why some needle valves leak and others don't, but I'm starting to lean with Keith Kraus' suggestion, which is to use only OEM valves and seats. Simply because it works. The question why is a separate matter. (I have a theory, but no guinea pig to test it on at present).

For the petcock, you'll hear a number of suggestions. I think that the vacuum operated petcock should be kept operational, for a few safety reasons.

Several of the folks here are convinced that petcock rebuild kits are useless, and your only real option is to buy a new OEM petcock.

For now, for people who are 100% sick of carb overflow & the ensuing problems, the consensus then is to go with OEM petcock, seats & needles. it's expensive, but it seems to be the only certain way to correct this BS once and for all.

(I would add: no doubt there are people whose overflow problems began when they installed carb rebuild kit(s). The machining on the parts is often abhorrent and inexcusably amateurish, and the f&^%#ing O-rings don't fit correctly. The consensus for a while now has been to buy gaskets IF you need them, valve seats & needles IF you need them, and an O-ring kit.)


The petcock does not, in any way, REGULATE the rate of flow. It should be either on or off. If you have overflow on a running bike (and it's not inhaling fuel through the petcock diaphragm via the petcock vacuum line) then there's a problem with the inlet valve.

Either:

1) the float is no longer buoyant enough or is badly adjusted, or

2)the valve is bad, or is being held open by some foreign matter.

And finally is the standard BWRINGER's lecture:

One of the secrets of the GS850 engine and carburetion is its outstanding low-speed manners. This, in turn, allows you to much more easily exploit the corners of its handling envelope, which leads to more giddy fun than you've ever had with your clothes on. As most racers eventually find out, smooth is fast.

If you had a freer-flowing aftermarket exhaust, a good set of K&N pods, a dynamometer, exhaust gas analyzers, a degree in chemical engineering, no neighbors to bother, a few weeks off work, a large box of Keihin jets, and several fifths of good tequila so you can sleep at night, you might be able to extract a few more horsepower from the 850 engine at certain RPM. And if you're really good, you might be able to get the low end half as smooth as it was stock. Maybe.

With the stock exhaust, forget it -- all you're going to do is screw up everything else quite badly to get maybe 5 more horsepower at 7,500 rpm or something like that. These things have a certain balance, and more intake flow must be balanced by more exhaust flow.

************End Quote************

Thank you for your indulgence,

BassCliff

[Danjal]

Throwing another wrench in the mix here... I have K&N air filters.... one on each carb. And the only other thing I can tell you about it is it has a 4 into 1 header.

Petcock functions fine. Tank off, theres no leakage in on or res. And it flows freely with pri. I took the liberty of waiting it out to see if all the fuel ran out of the line and through the carbs.. it stopped after a few mins. So I think its safe to say the petcock is non issue now. Needles and seats are incoming as are o-rings. Carbs have been triple cleaned now. And I mean every piece of the suckers is cleaned. The only way they're getting cleaner is if I stuff myself into them and check around the corners.


The idle of 3-4k rpm..is with and without choke. They engage correctly, so I think I can rule that out also. I beleive the needle diameter is to blame for the high idle. It is much thinner than a stock needle. Luckily I can also adjust those if it is a dynojet.

The only other thing I can think of doing it to set the float height higher and see if this takes out some of the leakage or all of it. The floats were checked also. Floated fine in water.

I'll wait till these parts are in, check them, then move on to air leakage fixes.

[Danjal]

Rained out at work today...so on to the bike.

Carb numbers are 43560 493

One odd thing on these carbs..the fuel adjustment screw on the backside has no hole for fuel overflow. Its just a straight through screw.

The boots for the carbs are fine. Still soft, no cracks or leaks.. they were on tight and the gasket was super clean where it mated up... definetly no leaks there.

Im tempted to get a drill bit a few thousandths over the needle size and open the valves up a tad to see if its a burr or wear on them. Should work if thats one of the problems.

[kudagra]

my ES was doing the same thing when I bought it. Turned out 3 of 4 of the pilot jets were plugged.

My suggestion?? Get another set of carbs, clean them up well and re-jet for your K&Ns and 4to1. Id say it sounds like the last guy who modified those carbs shouldnt ever touch tools.

[Danjal]

my ES was doing the same thing when I bought it. Turned out 3 of 4 of the pilot jets were plugged.

My suggestion?? Get another set of carbs, clean them up well and re-jet for your K&Ns and 4to1. Id say it sounds like the last guy who modified those carbs shouldnt ever touch tools.

If you see them you'll want to hunt him down. And if you do.. give him a few hits for me.

[Calvin Blackmore]

One odd thing on these carbs..the fuel adjustment screw on the backside has no hole for fuel overflow. Its just a straight through screw..

cant imagine what you mean by this
do you mean the centrally located screw for idle adjustment?

The boots for the carbs are fine. Still soft, no cracks or leaks.. they were on tight and the gasket was super clean where it mated up... definetly no leaks there.

The O rings sealing the joint between the carbs and the cylinder head would be suspect as well

[almarconi]

The problem is not with the carburetors, its with the OP. Can't you tell from the responses that no matter what is suggested, the OP has already done it. It doesn't matter what you suggest. It's obvious that his knowledge of carburetors is so vast that he already has the answer before you post a possible solution. All of the people who have posted a response are genuine in wanting to help solve the problem, they have taken the time to respond but it does not matter because the OP has already done what is suggested.

This post reminds me of a guy that will stop you on the street and ask you for directions then TELL you how to get there. All I have left to say to the OP is ..YOU OBVIOUSLY DON'T KNOW WHAT YOU ARE DOING OTHERWISE YOUR CARBURETORS WOULD NOT BE OVERFLOWING, YOUR IDLE WOULD NOT BE AT 3K AND YOUR BIKE WOULD BE FIXED. BE APPRECIATIVE OF THE KNOWLEDGE THESE PEOPLE HAVE GIVEN YOU. IF YOU LISTEN TO THEM YOU WILL FIX YOUR BIKE !

I'm outa this thread...

[Danjal]

The problem is not with the carburetors, its with the OP. Can't you tell from the responses that no matter what is suggested, the OP has already done it. It doesn't matter what you suggest. It's obvious that his knowledge of carburetors is so vast that he already has the answer before you post a possible solution. All of the people who have posted a response are genuine in wanting to help solve the problem, they have taken the time to respond but it does not matter because the OP has already done what is suggested.

This post reminds me of a guy that will stop you on the street and ask you for directions then TELL you how to get there. All I have left to say to the OP is ..YOU OBVIOUSLY DON'T KNOW WHAT YOU ARE DOING OTHERWISE YOUR CARBURETORS WOULD NOT BE OVERFLOWING, YOUR IDLE WOULD NOT BE AT 3K AND YOUR BIKE WOULD BE FIXED. BE APPRECIATIVE OF THE KNOWLEDGE THESE PEOPLE HAVE GIVEN YOU. IF YOU LISTEN TO THEM YOU WILL FIX YOUR BIKE !

I'm outa this thread...

Almarconi... Ive tried all the things that these folks are suggesting. I didnt try the boots to the carbs till posted. I posted Id try them once the valves were in. I took off the boots while I had time off.. I reposted back that they were fine. I also took the liberty of checking the o rings then.. so that suggestion was taken up and done. Most of the minor things I already checked before posting on here. So forgive me if you think im wasting your time when I went out of my way to read up on this forum BEFORE making a post here for technical help. I figured Id try it myself (after reading to see whos done what and how it was resolved) before asking for more help when its already posted before... Why ask what already has been?? Forgive me for being an ass if I say this but leave the thread if thats what you want to do. Just take your ball and go home. I am appreciative of the help, but its mostly things Ive looked into already. Seriously, thank you guys for wanting to help.

I already cleaned the carbs, set the floats, checked the floats, checked the needles and seats, installed new gaskets, I even checked the carbs with a LED light to make sure corners werent blocked, or jets werent clogged.

As per the advice of this thread I have checked the choke and throttle cables, pulled off the intake boots and cleaned them, checked the intake boot o rings while doing so.

Now since the valves are in the bike idles at 2.2k rpm's and dosent leak after shutdown. It still runs real rich and Ive managed to get the idle down. Any lower and it just dies. It can take a bit of throttle now, but still does with all of it, and flat out refuses to go past 7.5k. Insta stall if I rev it past that. It does leak while running though. The exhaust is rather black at an idle. The funny thing is its only running on the idle circuit....