84 gs550es boggs down after idle

[Anonymous]

Ive taken the carbs apart, cleaned them out pretty well, used carb cleaner, used fine wire to clean the jets out, and any other little screw with a hole through it. Made sure I could blow and see through them, and also checked the diaphram to see if tehre were any tears, rips, or cracks. Nothing. They looked to be in great shape. But when I start the bike, it starts right up on idle... but the second you touch the throttle, it dies. If you let it warm up for a while, then u can give it some gas, but it bogs down after 1500 RPM's. I replaced the coils, thinking it might be the problem because two of the 4 plugs were fouled out pretty bad. I also replaced the sparkplugs. I checked spark on all 4, and they all seem healthy and the same as all the others. I'm not sure what else to check now, what do you think I should start looking for? Im almost positive its running rich because of the fouled out plugs and the gas smell comming out of the exhaust. Mainly from the right side. Also the two plugs that like to foul out are on different coils :\. The only other things I can really think of now is if there is some sort of timing on teh bike that I could check. Maybe if the timing chain or whatever it uses, is lose because of a bad tentioner? Maybe mixture screws? I dont remember any screws that were only partly screwed in when i took them apart..

Any help or suggestions would be great. Im stumped.

 

[Dink]

Were the carbs balanced after the rebuild?
were the fuel and/or mixture screws adjusted?
Were the float levels adjusted correctly?and are they equal across all carbs?
Have you checked timing?
Have you checked for leaks in the intake boots?
Dink

 

[Anonymous]

Were the carbs balanced after the rebuild?

Balanced? Not that I'm aware of.. :\

were the fuel and/or mixture screws adjusted?

When I put them together, I put them back in the same amount of turns that I took them out. The bike did run before it sat about 2 years ago. or so im told.

Were the float levels adjusted correctly?and are they equal across all carbs?

Float levels? I'm pretty sure I I didnt adjust anything down by the float area, just put it back together the way it was

Have you checked timing?

No, I was actually wondering how to do that on this bike? Is it anything like a car?

Have you checked for leaks in the intake boots?

Intake boots, are you talking about the rubber boots from teh carb to the engine, and carb to airbox? I think they are alittle worn, Ill have to check again to see if they are leaking. If you were talking about the two rubberish thin things on teh top of the carb, I did check those, they have no leaks.

Sorry, I am a bit new at this, I've got a basic udnerstanding on this stuff, but I never really worked on carbs that much :\

JaKe

 

[Dink]

OK that explains your problems then, whilst you have done well and been very thorough within what you have done. It is the things that you havent done that are causing your problems.
Do you have a manual for the bike?
If so refer to it as it will actually show you all the steps mentioned in my first reply, except maybe the mixture screws (this is because pollution legislation says we are evil if we want our bikes to run correctly) so fortinately it is just a matter of some research and reading , getting a few tools and finishing all the good work you have done so off.
Dink

 

[Anonymous]

I can pick up a manual today or tomorrow, and ill check through everything. Is there a usual setting for the mixture screws? Like 2 and a half turns out or something? Just something to start with?

 

[KEITH KRAUSE]

Your mixture screws would'nt cause that problem. They are "generally" 2 turns out though. They should be adjusted out until you achieve the highest possible rpm's, then re-set the idle to about 1,100 rpm with the idle adjuster knob. Do this on a warmed up motor.
If the carbs are clean inside and the air filter is clean and the airbox sealed correctly, then I think it's either the diaphragm(s) were not installed correctly or the carbs need a manual synch followed by a vacuum tool synch, followed by the mixture screw adjustments.
It only takes one carb diaphragm or throttle valve to cause your problem.

 

[Anonymous]

Alright, well, I didnt get the manual just yet, but I did try something else on the bike. Keep in mind I am sort of new at this, so im not really sure what this means. But, I got the bike to start, idle like normal, this time I had the airbox not off, but took the boots connecting the airbox to the carb intake. This time, it idled, and as soon as i gave it gas it instantally bogs down. But, when I put my hand over the intake side, enough to let a small restrictive amount of air through, i could get it to go up to 2-2500 RPM's. I only had my hand over one side of the carb, its kinda hard to turn the throttle, and cover both carburators. Anyway, Im not really sure what that means.. but it may clue you guys into something. WHile i had the airbox disconnected, I also noticed that the (i dont know technical name for it) "Throttle valve cyclinders", or something, the things that should move up when the engine is running, and you give it some gas. They vibrated a little, but they didnt move up very much at all. All 4 of them were the same way. Which is what I also wanted to ask. What exactly creates the vacuum to lift those up? I know it pulls on teh diaphram on top of the carbs, which in turn pulls up on those cyclinders. Is it just the air from the intake valves? Does it have to do with the airbox?

Thanks for being patient with me.

Jake

 

[KEITH KRAUSE]

Many of the CV equipped GS models won't run well unless the airbox is on and completely sealed. When the motor is running, the throttle valve plates open and almost simultaneously the piston in the diaphragm raises.
I would try installing the airbox and see what the bike does.
As part of normal maintenance, I would still do a manual synch and follow that with a vacuum tool synch. Then adjust the mixture screws.

 

[Anonymous]

Alright, I put the airbox back on, and it still ran the same way. I realize the pistons are supposed to come up right when you give it throttle (which is cable operated to the butterflies) and inturn somehow.. which im still trying to figure out, creates either some sort of vacuum, or a blow, and rases the throttle pistons.

What I cant figure out is why mine still arnt lifting. I looked at all the lines going from the carb, and figured out what most of them are. The smallest one goes right to the petcock, i suppose for the vacuum operation when the petcock is in the on position. The largest one is for the gas, and goes right to the gas tank. Now, on my bike, when I got it, there was only one other line, it was a vacuum line type (not reinforced or anything) comming out of one of the carbs, and on the other carb, there was a spot for it, exactally in the same place, but no hose. The "vacuum" Hose wasnt hooked up to anything when i removed the carbs. I looked on the engine and didnt find any place for it to be connected, and the airbox only has two places to connect lines, one goes from teh airbox to the top of the engine, which i suppose acts like a PCV valve. The other one is on the bottem of the box, and im guessing acts like a drainage or something. I thought those two lines would be drainage as well, but im really not sure. Im thinking maybe they have something to do with the vacuum of those throttle pistons. What are those lines for?

I did put all the mixture screws all the way in, then 2 turns out each. I have a vacuum gage, but when you say do a manual sync, and a vacuum sync, im not really sure what your talking about. Someone told me to vacuum sync a carb, your supposed to hook the gage up to the engine (where i dont know) and turn each of hte mixture screws until you get the maximum amount of vacuum, then back it off 1/4 of a turn. Do it to all 4. I dont know if thats what your supposed to do, and if i was, where would I attach the vacuum gage?

Any help would be greatly appricated. This bike is really getting frusterating, ive never had these kinds of problems with bike carbs before.

Jake

 

[KEITH KRAUSE]

The two lines you are wondering about are the floatbowl venting lines. They should be routed under the seat and not kinked.
As for synching your carbs, you need a good manual. There are differences in carbs and I'm not sure of the balancing procedure for yours.
When I say "manual" synch, that means you adjust the balancing screws that adjust the throttle valves so they are in the correct positions and all uniform to the eye. This also has to be done in a certain order. This is then followed by a vacuum synch with a vacuum tool. This vacuum synch is far more precision than the manual synch. The manual synch allows the bike to start up and run, but the vacuum synch should always be done for best performance.
After the vacuum synch, you then adjust the mixture screws to achieve the highest rpm. If yours are out 2 turns, then try turning each one out a little more (or in?) and stop when the rpm's top out. Do this to each screw. When all four are set, adjust the idle to about 1,100 rpm's with the idle adjuster knob.
The closest model manual I have to yours, is for an '80 GS1000ET. If yours is similar, there are 4mm hex screws that screw into the head intakes, just in front of the manifolds. These screws come out and you install the carb synch tool's adapter tubes.
As far as I can see, there are only a few things that can cause your problem. The throttle valve(s) are either sticking or are way out of synch, or there is a vacuum leak in your diaphragm(s) or you've installed the diaphragm/spring assembly wrong. It only takes one carb to mal-function to cause your problem. Regarding the diaphragms, did you install them so the small "tab" aligns correctly? Are you also positive they are all supple and in perfect condition? Regarding the throttle valves, check them for smooth operation and then do the manual synch per your manual. If the bike then rev's as it should, then follow this with a vacuum tool synch and then the mixture screw adjustments.
I wish I could describe your models manual synching procedure, but that's why you need a good manual.
I hope someone here with similar carbs can help you. I hope I've helped you a little more with this post. Don't give up. You'll get it if you have patience. Carbs are very sensitive and the work has to be done right.

 

[Anonymous]

If yours is similar, there are 4mm hex screws that screw into the head intakes, just in front of the manifolds. These screws come out and you install the carb synch tool's adapter tubes.

I don't see those on my bike, but since laybor day is over, I can get myself a manual, and I think ill be able to find where they should be.

The throttle valve(s) are either sticking or are way out of synch,

I can move all 4 of them up, and they slide right back down, with almost no resistance.

Regarding the diaphragms, did you install them so the small "tab" aligns correctly?

Yes, I made sure of that. They wont seal otherwise. I know that your bike is slightly different in that you have 4 seperate carburators. I have 2 carburators, that are like 2 barrel each. On top by the diaphram, there are no springs like my old honda had, and one diaphram lifts up two of those throttle pistons at the same time. So if i move one on one of the carbs, the otherone in that carb moves up as well.

Are you also positive they are all supple and in perfect condition?

Yes. I have taken both of them off, and I know they are OK. I cannot see light through them at any place, there are no tears, or holes that I can see.

When you say Throttle vales, do you mean the butterflies? or those barrels that are supposed to lift, but arnt?

You have been a great help, now I have a starting point, and what to look for. I really do need that manual, but everything was closed the last two days. If anything else I'll have to order it from the net.

Thanks again for your help, and I will do the syncs and see how it goes. I may be back

Jake

 

[KEITH KRAUSE]

When I say throttle valves, I mean the butterflies as you called them. I'm just going by terminology used by the factory Suzuki manual for their BS CV carbs. The piston is what's in the diaphragm. On older VM carbs the throttle valves ARE the pistons or slides as some call them.
Maybe this will help you understand the operation of the diaphragm and piston. This is from the factory manual: The carburetor is a variable-venturi type, whose venturi cross section area is increased or decreased automatically by the piston according to the vacuum present on the downstream side of the venturi. Vacuum is admitted into the diaphragm chamber through an orifice provided in the piston.
Rising vacuum overcomes the spring force, causing the piston to rise to increase said area and thus prevent the air velocity from increasing. Thus, air velocity in the venturi passage is kepy relatively constant for improved fuel atomization and for securing an optimum ratio of fuel to air in the mixture.
Like I said, I'm not familiar with your carbs but I'm sure others here are.
If you make a new topic requesting info from other 550 owners, that may get you more answers. A good manual will fix you up too.
After the way you've described things, I'm sure your problem is carb synch (throttle valves) or diaphragm related. How about the vacuum orifice to the diaphragm chamber? Any way they are gummed up or blocked somehow? I've assumed the carbs are clean inside.