1985 GS550ESF Engine will not idle without choke

[victorgallas]

Hey

So I just got my 1985 gs550 running after two years of a slow restoration project. Once I got it running the engine would not stay running on its own without the choke being applied halfway. It would also be sluggish on revving and the idle would bounce between 1000 and 3000...
The carb was taken apart completely in the past and dipped in the carb cleaner fluid for a day or so to clean all passages. When I took the carb apart today I used a small hose to try on blowing air trough the passages and I noticed that the little bronze tube that reaches to the bottom of the bowl is clogged, so I am hoping that leaving it on the cleaner fluid will take care of it.

My question here is regarding the jets.
According to the Haynes manual, my carb should have the following:
Type: BSW30SS
Main Jets: 90, 97.5
Jet Needle: 5C-15
Clip Position: Not adjustable
Needle jet: P-3
Throttle Plate: 110
Pilot Jet: 37.5
Pilot air jet: 150

I had the carb with these settings when i was having these issues with the engine running. However when I went back on my old parts pile I saw that originally the carburetor had a Pilot air jet of 135.
What would be the ideal settings to cure this issue?

Mind you that when I pulled the sparks plugs out, Cyl 1 had a black tip on it while the rest of the spark plugs looked really clean as almost new. So i am a little lost as to what would cause one cylinder to have more fuel than the others..

Also I read about shimming the jet needle, My understanding is that by shimming you can make it run lean or rich. Is this a recommended method for tunning these engines?

Please any advice on getting it running better will be much appreciated.

Thanks a bunch

[Nessism]

Is the airbox installed and sealed tight? Did you replace the intake boot O-rings?

[Steve]

Running only with the "choke" on indicates a rather lean mixture.

Your 135 pilot air jets will richen the idle mixture a bit, so that doesn't make sense.

Your blocked "choke" tubes would not let it run on "choke", so that doesn't make sense, either.

Make sure your carbs are clean. No, I mean CLEAN. Did you replace the o-rings when you had the carbs dipped? Pointless to continue without good parts.

Answering a question: yes, changing the needle height will richen or lean the mixture, but only while operating on the needle circuit.
By some strange coincidence, the needle circuit is in use probably 80-90% of the time the bike is in motion.

Where are your mixture screws set? Not sure about the BSW carbs, but earlier 550s like to have them at 3 to 3.5 turns out.

.

[victorgallas]

Hey,

Yeah the airbox is sealed properly and properly tighten down.
When i did the rebuilt of the carbs i made sure to get all new jets and new o rings and gaskets, so everything shouldnt been leaking.
The only thing I can think is causing problems is maybe some blocked passages?

What do you guys suggest for setting the mixture screws on the mid 1985 gs550.? According to the haynes manual it should be 2 and half.

How much does messing with the mixture screws help on richening mixture to fix the issue of only running with the choke on?

Since the engine is running really lean, I was wondering what do you guys suggest to change on the carbs? I am just a little lost since I have chose all the jets and settings according to what haynes had on the manual....

[BassCliff]

Hi Mr. victorgallas,

When i did the rebuilt of the carbs i made sure to get all new jets and new o rings and gaskets, so everything shouldnt been leaking. The only thing I can think is causing problems is maybe some blocked passages?

If the carbs have been cleaned properly then there won't be any blocked passages. I have to ask, did you use THIS PROCEDURE to clean your carbs, soak the bodies and all the metal parts in carb dip (for up to 24 hours each) then reassemble with an O-ring kit from http://cycleorings.com? The aftermarket "carb kits" don't have all the O-rings necessary and are generally of lesser quality than the OEM parts. Just re-use all the stock jets after cleaning them, and replace all the rubber parts.

I know the "Carb Cleanup Series" procedure linked above is not exactly the same for your siamese carbs, but you'll get the idea. Did you remove the idle mixture screws and replace the O-rings underneath? The carbs have to be clean, clean, clean. For other necessary and critical tasks, click on your "mega-welcome" link and go through the maintenance lists.

Anyway, let me dump a TON if information on you and share some GS lovin'.

I just stopped by to welcome you to the forum in my own, special way.

If there's anything you'd like to know about the Suzuki GS model bikes, and most others actually, you've come to the right place. There's a lot of knowledge and experience here in the community. Come on in and let me say "HOoooowwwDY!"....

Here is your very own magical, mystical, mythical, mind-expanding "mega-welcome". Please take notice of the "Top 10 Common Issues", "Top 15 Tips For GS Happiness", the Carb Cleanup Series, and the Stator Papers. All of these tasks must be addressed in order to have a safe, reliable machine. Now let me roll out the welcome mat for you...



Please click here for your mega-welcome, chock full of tips, suggestions, links to vendors, and other information. Then feel free to visit my little BikeCliff website where I've been collecting the wisdom of this generous community. Don't forget, we like pictures! Not you, your bike!

Thanks for joining us. Keep us informed.

Thank you for your indulgence,

BassCliff

[victorgallas]

Hey cliff,

Thanks for the welcome and the links. I had actually gone trough youre links before and they are very good.

I had cleaned the carbs in the past by taking it all apart and letting it dip on the carb cleaning fluid in the can for a whole day per side. I also did get all the jets and orings new from suzuki, to make sure its all fitting properly and sealing properly.

The only thing I hadn't done when I first cleaned the carbs was to use a piece of wire to clean the passages, so I got a little wire cleaning kit that is used for cleaning oxy-acetylene torches and cleaned all the passages and now I am letting it sit for a whole day on a brand new can on crab cleaner dip to make sure its all clean. Tomorrow I will dip the other half and then ill assemble it.

I am planning to put the jets that the Haynes manual asks for.. but before she was running lean. What jet settings do you guys suggest using?

The current jet settings I got are listed on my first post here.