Gs550L project, starts with a lot of work, but will only just idle

[Guest]

Last summer I picked up a 1981 Suzuki GS550L. It had been parked for a long time and the lady didn't know if it was running before her dad stopped riding it. This was my winter project, but now I am really stuck and Spring is arriving! I have cleaned out the carbs and internal jets twice (following two different youtube videos). The gas tank is clean and has a new gas filter. I put in new plugs, just to be sure and I do have spark. I have a new battery in with a full charge. I put in new valve shims according to the specs in my manual. They were very tight, but now are about .10mm. I put in a new after market air filter (there was a mouse nest were the old one should have been). I tested the compression and it averages about 135 to 140 per cylinder. With some starter fluid, I can get it started. Once it warms up with the starter fluid (yeah, I know I shouldn't use that much starter fluid), it will just barely sit and idle on its own with the air filter in, but it immediately kills if I give it any throttle. If I keep the air filter off and cover it tighter with my hand, I can get it to rev a bit. I did just notice there is another jet on the outside of the carb apparently for the choke, that I haven't done anything with, but neither of my youtube videos said anything about that. Anybody got any ideas on what I should do next? Any help would be greatly appreciated.

[tom203]

"...did just notice there is another jet on the outside of the carb apparently for the choke, that I haven't done anything with"

the youtube videos might have lacked some fine points. But this "another jet" stuff suggests that you are refering to idle/air mixture screws as in this pic (marked 3 and 4) .Is this what you are refering to??

[tom203]

Moving on..... Cleaning this style carb is tricky... Have a look at members Nessism's work

http://zeus.mtsac.edu/~cliff/storage/gs/Mikuni_BS-CV_Carburetor_Rebuild_Tutorial.pdf

[Jim75]

Yes, those are the screws I just discovered and assumed they were jets. Is there something I need to do there?

[tkent02]

Yes, clean the carburetors properly.


Look at the link in post #3.

[Jim75]

I had a look at members Nessism's work and it definitely shows some things I missed. I will pull the carbs and get to work. Thanks so much for the help. I will let you know if this works.

[Jim75]

I followed the instructions in the link you sent and rebuilt the carburetors. Unfortunately the idle screw on #2 carb and one of the jets on the #3 carb were stripped and wouldn't come out. I cleaned them the best I could and reassembled everything. It started right up, but only ran on cylinders #1 and #4. Well, I guess I know where my problem is. I will look to replace the two bad carbs or get another complete set. It was great to hear it start though and know now what I need to do. Thanks for your help! It is greatly appreciated!

[Jim75]

I continue to look for #2 and #3 carb bodies for my 1981 GS550L. There are 1981 GS650 carb bodies for sale on eBay right now. Can anyone tell me if they will work on my 550? The OEM part numbers are different.

[Jim75]

Thanks for the tips guys. Here is the update. After cleaning the carbs using Nessim's guide, I still had some trouble starting and idling. I finally narrowed the problem to the aftermarket air filter I bought and the throttle cable sticking and holding the throttle open. Once I closed down the air intake a bit more and put on a new throttle cable, problem solved. It starts right up. I still need to do a carb since, but at least it is running.