GS550ESD with erratic idle

[Catalyst]

I just bought a 1983 GS550esd and I'm excited to get started however I am having some problems.

I drove out with a more mechanically inclined (though novice motorcyclist) friend to help me check it out and he gave me the thumbs up. By the time I got it home it was already late so all I could do was put it away and wait until morning to mess with it again.

When I went to turn it on in the morning I was surprised to learn that the bike which seemed so perfect the night before was acting decidedly wierd. I opened up the choke all the way and it started up however the idle was very erratic (dropping from 5k rpms to 3k without interference from me). After doing a bunch of research I have learned that there could be a few different problems but they all deal with the carburetor. I was told to see if there is an air leak however I don't know how to do that quite yet. I went and tightened the fasteners on carburetor rubber boots (?) to see if that might fix it however no luck.

My next plan was to check out the fuel bowl and see if there's any particles in there but I'm to be honest I'm hesitant to mess with it. My buddy says it would take 10 minutes to do it but still...

I'm still researching what I've got to do, but if this gets crazy complex I may just locate a mechanic and spend way too much money on getting this roadworthy.

[almarconi]

Checking for air leaks is pretty simple. Get a can of carb cleaner and spray it on the boots with the engine running. If the rpms change, you have a leak. You could also have a leak at the intake boot o-rings if your bike has them you didn't say what year your bike is.

Has the bike been sitting for a while? If gas has been left in the carbs for any length of time, they probably need to be cleaned.

[Catalyst]

The rpms already change on their own without using the carb spray so I don't exactly see how this works. The bike seems to be the PO's daily driver from the way he talks about the bike (i am still in contact with him)

[BassCliff]

Hi Mr. Catalyst,

Check the "Top 10 Common Issues" in your mega-welcome. As a general rule, most of the effort resurrecting these classic bikes involves new intake boots and O-rings for the carbs, a total carb rebuild, checking the airbox for leaks, etc. If you try to take short cuts you will become very frustrated.

Keep us informed.


Thank you for your indulgence,

BassCliff

[Catalyst]

Alright, so I went and drained the fuel bowls and I noticed a ton of rusty looking sediment in the gas. I drained/primed them a few times to see if I could get any of it out and it cleared up a little bit, but I figured there might be rust in the tank. I removed the tank and started to drain it but I noticed that what was coming out looked pristine and I collected a sample to make sure. I reattached the tank and primed it up and drained the fuel bowls again. The gas came out pretty clear. I drained the bowls and then primed and drained once more and the gas came out rusty and there was even some metal shavings in there.

So I guess the tank is ok and doesn't need to be cleaned out and relined and that the problem is somewhere between there and the fuel bowl.

P.S. The tank which is on it now is new. The old one it had was very rusted.

It was still stalling while trying to idle but I went and rode it around at around 70ish mph at points for a few miles. On the way back I stalled at a stop because I had to talk to the gate guard and didn't want to pull on the throttle while doing it. When I parked it I was messing with the idle screw and Ill see if it decides to stay on tomorrow.

[almarconi]

If the gas looks like that more than likely the carbs need to be cleaned. The passages in the jets and the carbs are tiny and easily clogged. I know you'd rather ride the bike than clean the carbs but I'm afraid the bike is not going to run right until you do. It doesn't take much to clog the carbs. It may also be worthwhile to drain and clean your gas tank. I would also remove the petcock and flush out the screen.

[TheCafeKid]

I just put a new motor in a 550ES for a buddy. The boots from the airbox to the carbs (assuming yours still has em) are more deceptive than most other bikes I have worked on. If they are hard...as in dont flex, get new ones. The way that bike is set up, with those siamese carbs, its difficult to tell if the boots are actually sealing because you cant see all the way around them. The new boots are SUPER pliable, so if yours arent, this will be a large part of your problem...I fought and fought that thing thinking the boots were sealing because they for all intensive purposes LOOKED like they were...they werent, and I felt like an idiot once i realized

[Catalyst]

I will definitely be getting to the carbs in the next couple of days, but I didn't have time to do it before going to work. I just wanted to see how it would run while actually riding it up the road.

My goal is to give this the TLC it deserves and extend it's life by atleast another 26 years.