Stuttering up to 3k rpms, won't idle without choke.

[Spiff]

I think it's because it's running lean.
It's a 83 GSX1100ES. It won't idle without a little bit of choke, if I turn of the choke it will idle for a couple of seconds then slowly die. Doesn't matter how far in I turn the idle screw, I set it to idle at 2500rpms but still it just died...
So I think something is wrong in the idle department.
It also stutters and jerks violently when trying to apply slight throttle from idle and up to about 3000rpms, beyond that it's silky smooth power delivery.
Again a reason why I'm suspecting something in the idle department...

Should I try adjusting the air screw?
EDIT: MIXTURE screw was probably what I meant.....

EDIT2: Strip/dip is planned....

 

[koolaid_kid]

Sounds like your pilot circuit is clogged. Time to strip & dip. Have fun, and be sure and follow Nessism's guide to the letter. Taking shortcuts means a re-do.

 

[Badooka]

+ 1 Koolaid Kid

 

[megatwin]

You also should check the spark on all the plug leads,you may have some bad caps,or coils.
If it's not sparking on all cylinders,you can work on the carbs for years without fixing them.
Check compression,also.

 

[Guest]

It needs to have the carbs cleaned , a proper strip and dip with new O-rings and it should run like new again

 

[Badooka]

You also should check the spark on all the plug leads,you may have some bad caps,or coils.
If it's not sparking on all cylinders,you can work on the carbs for years without fixing them.
Check compression,also.

If he is fine at other rpm's and needs to use choke to idle- there is nothing else to look at- it's the carbs. Compression shouldn't even be an issue-
learn to troubleshoot, not chase.

 

[Spiff]

I'm bumping this thread since I now have an update and I'm somewhat confused.

I have not started or run the bike since it fell over sometime late january and cracked the stator cover.
Now thursday I got it running again, I have not done ANYTHING to the engine/carbs except checked/adjusted valves and replaced stator gasket and valve cover gasket. But it's running fine now. It started and ran fine indoors, didn't die on idle and idled and ran fine without choke...
I took it for a test run and yeah there was some minor irregularites felt in the idle/slow circuit but nothing too bad, certainly nothing like the bonerattling stuttering i felt when I ran it in january and nothing that made the bike unridable or something that could wipe the smile of my face....

So I'm wondering what could have happened? I recently read something about carbuttor icing, could that be what happened? It was pretty cold that day, between 0 and 5 degrees C.
Could it have been bad fuel? Particles in the fuel?

The carb rack is off now for a strip and cleaning, I have only removed the fuel bowls and everything inside there is clean as a whistle, the slides also move freely and the spark plugs are a light brownish color like they should be on a good running engine....

So I'm curious about all this....

 

[tkent02]

Not running in cold weather and rinning better in warm, could be its too lean, the cold air is more dense and so it's actually leaner in winter than it is now. Just barely too lean to run nice in the cold, in warmer weather it works better. Carburetor icing is not likely with the stock air box, and it usually occurs on very humid days, was it humid that day?

Bad gas didn't get better by itself, did you get drain the old and get new gas?

I'd go with the lean mixture thing, which means you need to to a proper carburetor cleaning. Visibly clean as a whistle means nothing, you can't see inside the tiny passages that clog up.

 

[Spiff]

No, was pretty dry, just cold...

The gas, yes, well I tipped the bike over after I came back from the ride(i filled it up too while on the testride,full tank of fresh gas) so alot of gas went on the floor, some in the engine (yes I have changed oil) and a good deal ON the engine ;-)

Upon starting it now Thursday gasoline poured all over again because the fuel filter the previous owner had fitted is of the type that can be dismantled and it had worked it self loose. Maybe it was clogged before or something, I don't know. Gonna rebuild them anyways now, just puzzled by how it worked so fine now while it was s*** before but your theory sounds plausible though

 

[tkent02]

Lose the inline filter, it isn't needed unless the tank is rusty. A lot of times they cause problems. If the tank is rusty fix it.

 

[Spiff]

Lose the inline filter, it isn't needed unless the tank is rusty. A lot of times they cause problems. If the tank is rusty fix it.

I'm planning on it as the tank is fine inside.

 

[JTGS850GL]

Maybe you had a stuck float and the tumble loosened it up. Just guessing. Agree with above about it's probably running lean. I still think a good strip and dip couldn't hurt. Not really that hard to do once you get the carbs off.

 

[Spiff]

But man them carbs is hard to get off! Or rather the air box

I'm actually in the process of cleaning them as we speak.

http://www.thegsresources.com/_forum/showthread.php?p=2034888#post2034888

 

[Steve]

But man them carbs is hard to get off! Or rather the air box

This is about the time where some guys will say "screw the air box, I'm going to switch to pods".

Pods will make carburetor removal easier, which is good, because you will be removing them PLENTY of times, getting the jetting correct.

On the other hand, clean the carbs properly, you won't have to remove them for another 10-15 years.

Of course, that assumes that you winterize properly, if necessary, and keep up with all your other maintenance. :-\\\

.

 

[Spiff]

The fact that this bike is equipped with a 4-1 exhaust, could that have anything to say on it running slightly rough in the idle/slow section?

 

[JTGS850GL]

I don't think so. The 4-1 may need a larger main or a slightly raised needle position but that shouldn't have any effect during idle. In fact it should have more effect at the higher RPMs.

 

[Spiff]

Okay! Today I tried to adjust the carbs but to no luck, it still stumbles and rattles and idled erratic, no matter how I turned the fuel screws it didn't seem to have any effect unless I turned them all the way in which would make it die...

Finally I turned my attention to the spark plugs and NONE had the correct gap plus I don't know how old they are.
I adjusted the gap and boom! Instant results. Smoother idle, smoother engine, less rattling. I can rev it over 6000 now whitout the engine sputtering and stop!
Also the rpm gauge now follows all the way up to 7000 whereas before it would stop at 5000 and go haywire! (connected?) I didn't dare any higher 'cause it's raining and the tires are old....
A definate improvement but still not 100% perfect. I'm gonna buy some new plugs and take it from there. Any suggestions as to where to go from there, carb sync obviously but idle mixture appears good now.