Hanging idle after repairs

[swedge61]

I trailered the bike (1983 GS1100GK) on a trip. Pulled the bike off the trailer and it would not start. No fuel in the bowls. The petcock was working. I blew into the fuel line. It was stopped up but blockage broke lose. Fuel to 3 carbs but bike still would not start. After getting home, I pulled the carbs, partially disassembled them and sprayed everything out. Previous owner had the carbs rebuilt, they were pretty clean except junk in bowls. I broke one of the stands that holds the float pin. 3btc sent me a set of old carbs he had laying around. Before they arrived, I put the carbs back together. Bent the float pin in carb with broken stand so it would physically hold stand in place. This was a temporary fix. Just curious if bike would run. Bike starts but Idle is hanging. Adjust mixture screws, but nothing changes.
Pulled everything back off and here is what I have done:
Adjusted valves
Replaced intake boot o-rings.
Intake boots were sill soft and I could see no cracks
Replaced #2 carb body
Complete disassemble of carbs, dipped, sprayed with carb cleaner, blew out with compressor and cleaned up.
All new o-rings in carbs.
Adjusted floats.
Bench synced carbs
New clamps for intake boots
New plugs
Here is the problem
Bike starts but idle hangs. The hotter it gets, the longer it hangs. Bike runs down the road good except for the hanging idle until it gets hot, then it wants to die at idle. I have adjusted the mixture screws on the engine side of the carbs. It doesn’t make a difference if the screws are ¼ turn out or 3 turns out. The bike still runs the same. It doesn’t seem like the screws change anything except if I screw the number 1 screw all the way in and then the idle raises a little. I have sprayed wd-40 on both ends of the carbs trying to see if there was a vacuum leak. No change in idle. I have checked the air box and everything appears normal. The new spark plugs are black and sooty indicating a rich condition. They were black and sooty before repairs.
The problem didn’t start until I pulled the carbs the first time. The bike ran rich but ran good. The only thing I haven’t done is change the intake boots, but they looked good and I didn’t have a problem before.
Give me some ideas guys. I am about ready to sell the thing.
Thanks
Swedge61

[elevatorman71]

I trailered the bike (1983 GS1100GK) on a trip. Pulled the bike off the trailer and it would not start. No fuel in the bowls. The petcock was working. I blew into the fuel line. It was stopped up but blockage broke lose. Fuel to 3 carbs but bike still would not start. After getting home, I pulled the carbs, partially disassembled them and sprayed everything out. Previous owner had the carbs rebuilt, they were pretty clean except junk in bowls. I broke one of the stands that holds the float pin. 3btc sent me a set of old carbs he had laying around. Before they arrived, I put the carbs back together. Bent the float pin in carb with broken stand so it would physically hold stand in place. This was a temporary fix. Just curious if bike would run. Bike starts but Idle is hanging. Adjust mixture screws, but nothing changes.
Pulled everything back off and here is what I have done:
Adjusted valves
Replaced intake boot o-rings.
Intake boots were sill soft and I could see no cracks
Replaced #2 carb body
Complete disassemble of carbs, dipped, sprayed with carb cleaner, blew out with compressor and cleaned up.
All new o-rings in carbs.
Adjusted floats.
Bench synced carbs
New clamps for intake boots
New plugs
Here is the problem
Bike starts but idle hangs. The hotter it gets, the longer it hangs. Bike runs down the road good except for the hanging idle until it gets hot, then it wants to die at idle. I have adjusted the mixture screws on the engine side of the carbs. It doesn’t make a difference if the screws are ¼ turn out or 3 turns out. The bike still runs the same. It doesn’t seem like the screws change anything except if I screw the number 1 screw all the way in and then the idle raises a little. I have sprayed wd-40 on both ends of the carbs trying to see if there was a vacuum leak. No change in idle. I have checked the air box and everything appears normal. The new spark plugs are black and sooty indicating a rich condition. They were black and sooty before repairs.
The problem didn’t start until I pulled the carbs the first time. The bike ran rich but ran good. The only thing I haven’t done is change the intake boots, but they looked good and I didn’t have a problem before.
Give me some ideas guys. I am about ready to sell the thing.
Thanks
Swedge61

did you replace the intake o-rings that go between the intakes and the heads a real good way to see if there is an air leak is spray anything flamable like hairspray towards the intake boots and if the revs up you def have an air leak

[almarconi]

Check your timing. I would also measure the voltage at the coils. How does the spark look. Sometime ignition problems can appear to be fuel problems and vice versa.

[swedge61]

The o-rings on the intake boots were replaced.The bike starts good, idles ok and runs good when cold just the hanging idle problem. I don't think the timing would have changed. The spark looks ok but not as bright as I would like it. I am going to replace the coils next spring when I have more cash. The bike was fine before I started messing with it due to the fuel lines being stopped up. I will check the voltage at the coils if I need to pull the tank again.
Any other suggestions
Swedge61

[Nessism]

Where are the idle mixture screws set? Did you adjust them to obtain the highest idle?

[swedge61]

right now they are at 1 turn out. It doesn't seem to matter how many turns the screws are at, the idle never changes. I have had them at 1/4 turn out and as high as 3 turns out and the idle doesn't change. The only time the idle changes is when I screw the #1 screw all the way in then the idle raises slightly. Before I tore the carbs down the screws were all 1/3 to 3/4 turn out.

Swedge61

[almarconi]

Before I tore the carbs down the screws were all 1/3 to 3/4 turn out.

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.

[swedge61]

I checked the parts in the carbs to see if they were stock because I had some question about the last rebuild. Everything was correct except the mixture screws looked different than the ones that came in the extra set of carbs I received, so I put in the ones from the extra set because they look correct. I can move to 1.5 to 2.5 turns out but it doesn't seem to change anything. The only other thing different were the slides. In the slides in the original carbs, the needle hanging down out of the slide could be pulled down. The ones in the extra set the needle thing could be pushed up. Steve said the spring went in first and would allow the needle thing to be pulled down so I left them in the carb.
Swedge61

[81gs1100]

I would check the fuel screws... If you are not getting any reaction from turning the screws in or out, they are more then likely just an air leak now, replace o-rings.

Running lean will cause the idle to hang.

Try starting the bike and spraying wd-40 or something on top of the fuel screws and see if it stays puddled in the hole with the screw or if it gets sucked into the motor. Or you might notice the idle rev up if they are leaking. doing this test may narrow your search down.

Just an idea

[Nessism]

Try 2.5 turns out and see if the idle still hangs. I they do, try 3 turns. If they still hang, I'd pull the carbs and go though them to make sure everything it right.

[smagnusen]

Is your choke closing completely? New choke plunger o-rings?

[swedge61]

Carbs were cleaned thoroughly, dipped, sprayed out with carb cleaner, then cleared out with air compressor. All o-rings in carbs have been changed. I got a o-ring kit from Robert Barr. Choke o-ring was changed also. I will try putting wd-40 on top of mixture screws to see if they leak.
Swedge61

[swedge61]

Chokes are also closing good

[swedge61]

Today I set mixture screws to 2 turns out. Started bike and it went straight to 2500 rpms. It stayed there for short time then settled down to idle. Reved up motor and idle hangs. Warmed up the bike and then shut it off for a few minutes. It seems like if I shut the bike off and let it sit, the heat builds up faster without using all the gas. I start the bike back up and raise engine to 3000 rpms and release the throttle. The bike stays between 2000 and 3000 rpms. I shove down on the number 3 carb throttle lever to make sure butter flys are closed and they are. The rpms are not steady but stay high. The only way to get the engine to return to idle is to hit the choke lever, then it goes back down to idle. I misted the intake boots with starter fluid and the rpms did not change. I did the same to the boots on the air filter side, still no change in idle. I shut the bike down and set the mixture screws to 3.5 turns out. Restarted the bike and nothing changed.
I was thinking that the intake boots were bad but the idle did not change when starter fluid was sprayed on the boots. The only thing I can come up with is a problem in the carbs but everything went back together without a problem.
Still looking for the smoking gun before I use one on the bike
Swedge61

[BassCliff]

Hi,

Could there be a small pinhole or tear in the slide diaphrams?


Thank you for your indulgence,

BassCliff