Okay.. So THIS is where I am at..

[1980_GS550L]

So I have had my bike (1980 Suzuki GS550L) since about July - August of 2011. I left to do some training with the Army and left it how it was. The carbs have been cleaned, breather hose, tank coated, new air filter, new petcock, battery, new fuel line new spark plugs, changed the oil and filter,negative battery wire (relocation), new intake tubes and o-rings.

Before I left I was able to get the bike started but had a high idle so that is when I replaced the intake boots along with the o-rings. when I got back, I replaced the petcock,fuel line, spark plugs, oil and filter and went to go start it the other day. It struggled at first but finally got it to start up again with high idle. It would only start on full choke. Gas was puddling inside the air box and flowing out the overflow line so naturally I thought I flooded the carbs. I adjusted the synch screws (not knowing that's what they were at the time) on top of the carbs and started the bike again. This time it started, on full choke but had low idle. The fuel was still puddling inside the air box and draining out of the overflow line.

I went out to the garage today to start the bike. Started up but again with low idle BUT only on full choke, and no throttle. Opened the throttle and it died. No fuel was puddling up in the air box this time. I started it up again without the choke and with the throttle open and it also started back up but once I let go of the throttle it died. Fuel had begun to start leaking somewhere from carb 2 or the exhaust boot, not sure where from.

I have read the thread on bikecliff website but some links wont open up on my computer. I have a Haynes manual but does me no good at this point. I am new to motorcycles but am familiar with cars, however I am stumped. Please if anyone can help diagnose this it will be much appreciated.

[TheCafeKid]

Sounds like your float measurements/settings are quite off, and/or your needle valves are trash. You didn't leave it on prime the whole time did you? You really need prime only to fill the bowls after sitting a while. Before trying to start the bike, switch the tap to prime, count to five or ten alligators and flip it back to "ON" (assuming you have more than a gallon of gas in the tank, otherwise switch it to reserve) give it some "choke" and try to start her.

But before you do that, I'd re-measure your float height, making sure they're correct and measured correctly. And also inspect the float needles. If they've got a scored ring in the tip you can feel with your finger nail, they probably should be replaced.

After doing this, re-set your mix screws to 3 turns out from lightly seated. This should be good to get it running and idling. If you have a high idle adjust the idle speed knob until it idles around 1100 rpm. If it will, your on the right track, if not we'll trouble shoot from there..

[allojohn]

At the very least the float valves are sticking. So you might as well go the whole hog and clean the carbs. BassCliff has the info. Next up will be adjusting the valves shims. Once you've got to that point we'll see what else needs to happen.

Download the Workshop manual from BassCliff and go buy the Clymer manual. Both are better than the Haynes.

[1980_GS550L]

Are the mix screws the one on top of each carb? I am pretty sure I am going to rebuilding the carbs again. Should I use new rebuild kits? The ones currently in them are about 6mo old...

No I never had the petcock on prime.

[tom203]

Stupid question.... this is not 6 month old fuel, left sitting in carbs untreated?
The idle air mix screw is on top of carb on engine side in mini tower.

[mike_of_bbg]

Did you use full carb rebuild kits, and not just replace the o-rings? The full carb kits have a reputation for sub-standard machining. Better to re-use the stock jets, needle valves, etc. - there's really nothing to wear out on them, they just need to get cleaned. Usually all you need are the o-rings, maybe the pilot jet plugs, and sometimes gaskets (those are usually re-usable, too). It's the rubber bits that give up.

Re: fuel pulling in airbox. Sometimes some gentle rapping with a block of wood on the float bowls will get the needle valves to seat again. Could it also be that your petcock is shot and fuel is coming down through the vacuum line?

The screws on top of the airbox side of the carbs are the idle mixture screws. The sync screws are the ones with the lock nuts between the carbs linking the throttle plates.

You should definitely re-dip the carbs and have new o-rings on hand just in case. In six months of sitting some of that fuel is going to have jelled. The pilot jet and passages to the idle screw are very small, and even a little bit of jelling of fuel can dramatically cut off fuel flow at idle.

[Steve]

I went out to the garage today to start the bike. Started up but again with low idle BUT only on full choke, and no throttle. Opened the throttle and it died.

Sounds normal to me.

The proper way to start the bike is to apply "choke", press the starter, do NOT touch the throttle. Adjust idle speed with the "choke" knob.

These bikes do not have a traditional choke that blocks off the intake, they us an "enrichener" system that provides its own mixture. It relies on the closed throttle for the high vacuum necessary to draw air and fuel through the system. If you open the throttle at all, you lose the vacuum and your enrichener system.

Are the mix screws the one on top of each carb? I am pretty sure I am going to rebuilding the carbs again. Should I use new rebuild kits? The ones currently in them are about 6mo old. ...

If you used "rebuild kits" (the ones that cost about $20-25 each), you probably wasted your money. There is a good chance you got inferior parts that do not fit properly. Getting newer, inferior parts will not help.

Here is where your IDLE MIXTURE ADJUSTMENT SCREWS live:


.

[1980_GS550L]

Sounds normal to me.

The proper way to start the bike is to apply "choke", press the starter, do NOT touch the throttle. Adjust idle speed with the "choke" knob.

These bikes do not have a traditional choke that blocks off the intake, they us an "enrichener" system that provides its own mixture. It relies on the closed throttle for the high vacuum necessary to draw air and fuel through the system. If you open the throttle at all, you lose the vacuum and your enrichener system.



If you used "rebuild kits" (the ones that cost about $20-25 each), you probably wasted your money. There is a good chance you got inferior parts that do not fit properly. Getting newer, inferior parts will not help.

Here is where your IDLE MIXTURE ADJUSTMENT SCREWS live:


.

Those are the ones I adjusted and the idle came down. I pulled my plugs last night and they are black, (too rich) so I need to replace those again. To answer other questions: No its not 6 month old fuel in the carbs. I drained the system and then the other night, I put new fuel in. The petcock is not bad, I replaced it, not re-built it and I can see the fuel stop flowing from it when it don't need it and flow when it does. The re-built kits (price and brand unknown- I did not rebuild them myself) came with everything apparently but the diaphragms.

[Suzuki mad]

Was the bike running Ok when you bought her or was she a non runner?

[1980_GS550L]

Was the bike running Ok when you bought her or was she a non runner?

I inherited it off of my father in law. It has not been driven (or ran) since about 1984-1987ish. When he garaged it, it ran fine. I know part of the problem is the fact is that it sat for so long, that is why I had the carbs rebuilt and replaced all that I have so far on it. I just want to get this beauty back up and running like the day it came out of the factory.

EDIT: Sorry. To answer the question, no it did not run too good when I inherited it. It had high idle. When my father in law stored it however, it was running great.