Hanging idle after repairs

[swedge61]

The throttle cable was the first thing I checked. I had a problem once before when I turned hard to right it would cause a bind in the cable and increase the rpms. The cable now has a little slack in it. When the idle hangs I have shoved down on the linkage and it would not move.
One odd thing is if the idle hangs and doesn't come back down to idle, I can hit the choke and it will drop down to idle almost immediately.
Would the float height cause a hanging idle that gets worse as the bike gets hotter? I adjusted the floats up from around 20 or 21mm to 22.4mm
I am going to look at the airbox next. Bench syncing is the best I can do right now. I have no money for any extra tools.
Thanks for all the replies
Swedge61

 

[Nessism]

The throttle cable was the first thing I checked. I had a problem once before when I turned hard to right it would cause a bind in the cable and increase the rpms. The cable now has a little slack in it. When the idle hangs I have shoved down on the linkage and it would not move.
One odd thing is if the idle hangs and doesn't come back down to idle, I can hit the choke and it will drop down to idle almost immediately.
Would the float height cause a hanging idle that gets worse as the bike gets hotter? I adjusted the floats up from around 20 or 21mm to 22.4mm
I am going to look at the airbox next. Bench syncing is the best I can do right now. I have no money for any extra tools.
Thanks for all the replies
Swedge61

Did you at least try 3 turns out on the mixture screws? Pretty easy trial and nothing to loose. Regarding the sync tool, you might want to complete your profile so people can see where you live, there might be a GSR member near that can help you out.

 

[swedge61]

I am now at 3.5 turns out and still having the problem. I went to 3 first then 3.5.I will complete my information.
I live Louisville, Ky by the way.
Swedge61

 

[TheCafeKid]

That seems awfully lean to me unless the pilot jets have been changed. I would expect 1.5-2.5 turn out with stock pilots.

If he's running a stock set up, I wouldnt expect the .75 turns out to be all the remarkable... Remember these were set pretty lean from the factory. Just for kicks, the last few sets of stock UNTOUCHED carbs ive done ive pulled the adjustment screw plugs on and counted what the factory had them set at. On the SAME SET of carbs, ive seen one carb be 2 turns out, another be .75 turns out, yet another at 1 turn out, and the last be 1.75 turns out. They set them for what made the bike run the best at the time of production, and still kept it within the regulatory specs thru the rev range. And, as Ed has said, 2 turns could be JUST not enough, and 2.25 be perfect. When I was finishing up Chris Riddle's bike (Mike Riddles son...550ES) the bike simply wouldnt idle with the screws 2.5 turns out, I was getting very angry, because id gone thru everything else repeatedly. Then on a whim i turned them all 3 turns out, and it fired right up and ran like a champ. They can be very finicky, confusing and totally illogical peices of equipment sometimes...LOL

IF you are already three turns out, you might be best to pull the carbs again as Ed has said. It sounds as if you have some clogging still in the pilot circuit. When you take them down again, record what jet sizes you have in each carb, its possible someone has messed with them in the past? Make doubly sure that your cleaning out your pilot jets with carb spray, air, and fine strands of copper wire thru all of the jet holes, as well as spraying out the passages with carb spray. If the carbs werent properly rinsed after dipping, and carb spray and or air not used in the passages, that dip turns into some gooey crap when its allowed to dry.. ALSO, double check your FLOAT LEVELS. These are very important for proper idle as well. If they are not allowing enough fuel into the bowls, you will have these symptoms as well...

 

[swedge61]

I dipped the carbs, ran a wire through every hole I could find, Used about one can of carb spray per carb, making sure when I sprayed in one hole it came out somewhere else. Then I used my air compressor to make sure nothing was left in them.
I took a magnifying glass and checked the jets and compared the marking to what was in one of the post about what was stock in the carbs and everything matched.
I am beginning to suspect the float levels because they were changed from when the bike was running before this mess started but I can't figure out how they would affect the idle that much and get worse as the engine gets hotter.
Swedge61

 

[TheCafeKid]

Dumb question perhaps, but did you try turning the idle speed adjuster down once the bike was warm???

 

[swedge61]

When the bike is cold it will idle at 1000 rpms and hang for a split second at 2000 rpms on it way down to idle if reved up. After it gets hot it will idle but if you raise the rpms to around 3000 it will hang and stay between 2500 and 3000. Sometimes it will come back down to idle speed or if I hit the choke it will drop right down to idle speed.
I will try moving the idle adjuster out when it hangs to see what it does. I will try anything now. Well almost anything
swedge61

 

[gs_schmuck]

Sticky carb slides?







.

 

[swedge61]

The slides can be lifted easily and drop down smoothly. No sticking that I can see.
Swedge61

 

[almarconi]

I can't figure out how they would affect the idle that much and get worse as the engine gets hotter.

The float height effects all the circuits. You should also verify the fuel level in the bowls.

Since the idle drops when you add choke this would suggest to me that you are lean on your pilots. This sort of makes sense since the screws were only open about 3/4 of a turn. When you replaced the pilot screws was the rubber washer, metal washer and spring installed on the screw?
The order should be spring, metal washer and then rubber washer.

 

[81gs1100]

The float height effects all the circuits. You should also verify the fuel level in the bowls.

Since the idle drops when you add choke this would suggest to me that you are lean on your pilots. This sort of makes sense since the screws were only open about 3/4 of a turn. When you replaced the pilot screws was the rubber washer, metal washer and spring installed on the screw?
The order should be spring, metal washer and then rubber washer.

Backwards: If the bike runs better giving it more gas, (choke) then it is lean, if the bike dies or starts to stumble, too rich.

 

[TheCafeKid]

Uhm.. thats a neat little theory, but one that i've always considered pretty bogus anyway.... the "CHOKE" isnt truely a choke, but an enrichening circuit. However, as soon as you open the throttle, at all, you destroy the vacuum that circuit was using to pull fuel. Also, if you look at how the choke works when you accuate it, you can see the choke barrel slide out and leave an opening in the diaphram housing. In my reasoning, this is the "stumble" or hiccup that some people feel when they open the choke with the bike in heavy throttle. The diphrams lift is momentarilly disturbed. My 1100ES is pretty close, according to plug chops, to just about mixture perfect in all throttle ranges (except idle, oddly enough) and whether or not it was rich or lean when I was tuning it, and other bikes, I got nearly the same reaction from playing with the choke lever... This is why I think that little test is pretty much useless.

 

[supertech411]

I'm having a similar issue with my GS550T, except there are times when it will idle normally. Usually the idle hangs when it's hot also. I'm posting because someone said an ignition problem could cause similar symptoms. Do the coils gradually loose their ability to provide spark, or do they just die? I'm wondering if my coils (The bike is a 1981) are weak. If someone could elaborate, that would be great.
Also, why would the bad seal on an airbox cover cause problems? I understand a bad filter to airbox seal affecting things, but not why the cover seal would.
Good luck fixing your 850!