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**duaneage** · 04-22-2005, 05:00 PM

Re: Need help with 1980 GS550L Carbs

[quote="lbowles2"]
I didn't ask but I assume he synchronized them. Didn't know enough to ask at the time :roll:

A buddy of mine has been helping me work on the bike. We cleaned the gas tank out as best we could because the bike had been sitting for a year or two and the fuel was pretty well varnished. I also took out the petcock and cleaned the screen on it. (I will ask another question about the petcock at the end of the post.)

When I try to start the bike it pretty much does nothing unless I have the choke all the way out. Unfortunately the choke won't stay out by itself so I have to hold it out. That means that I have to have someone help since I only have 2 hands :roll: Anyway, if I have the choke all the way out it will kind of start but it will only run for a few seconds while I give it a little throttle. I just can't get this thing running.

My first big question: I know that I shouldn't have to hold the choke open. Could it have been put together wrong? I see that it is sliding the rod that links the choke on all the carbs (sorry for the horrible terminology... i'm kind of a noob when it comes to this stuff) but it just springs back about half way.

Now I have a question about the petcock. I know that it is vacuum driven but I saw several references in the Fuel/Exhaust Q&A page about being able to set it to Prime. Would you guys recommend doing this? If so, how do you do it? Is there a valve that you have to turn to allow gravity to pull the fuel into the bowls??
carburetors. Any help you guys can give me would be appreciated

quote]Carbs are synchronized on the bike with a special tool that reads the engine vacuum and allows you to match carbs 1,2 and 4 with #3 ( #3 is the reference) These tools are about 40 dollars, a shop might do it for 1 hour labor, best to find someone on the forum near you that can help.

The choke cable can be firmed up by giving the choke house a twist and causing the cable cover to bind the cable just a little. My 650 comes out of the center of the steering assembly, I have it a little twisted so it meets resistance and does not drop. There is a compression fitting on the end that is supposed to hold it but it sucks. You could also sip a screwdriver doen there where the lever moves on the carb to hold it on for you, or grow another hand

If you put the fuel to PRI the vacuum control is bypassed. Gas will run straight into the carb. Try and start it in this position. Instal a fuel filter to protect your carbs, I have a clear plastic one that lets me see the gas flow.
Did you connect the hose from the #2 carb to the vacuum port on the petcock? sometoimes people hook up one of the fuel bowl vent hoses there instead, no vacuum comes from the two fuel bowl vent tubes.

Are you sure the boots are not cracked and leaking very badly? Intake boots between the carb and head can separate from the aluminum flange and cause real trouble.

**Anonymous** · 04-22-2005, 05:14 PM

Re: Need help with 1980 GS550L Carbs

Originally posted by duaneage

Carbs are synchronized on the bike with a special tool that reads the engine vacuum and allows you to match carbs 1,2 and 4 with #3 ( #3 is the reference) These tools are about 40 dollars, a shop might do it for 1 hour labor, best to find someone on the forum near you that can help.

Yeah I would really like to find somebody who could help me with this. I have been trying to find people who work on motorcycles on the side but haven't had much luck

Originally posted by duaneage

The choke cable can be firmed up by giving the choke house a twist and causing the cable cover to bind the cable just a little. My 650 comes out of the center of the steering assembly, I have it a little twisted so it meets resistance and does not drop. There is a compression fitting on the end that is supposed to hold it but it sucks. You could also sip a screwdriver doen there where the lever moves on the carb to hold it on for you, or grow another hand

I think I will just try growning another hand... that shouldn't be too hard

I will have to try that with the cable and see if it helps.

Originally posted by duaneage

If you put the fuel to PRI the vacuum control is bypassed. Gas will run straight into the carb. Try and start it in this position. Instal a fuel filter to protect your carbs, I have a clear plastic one that lets me see the gas flow.
Did you connect the hose from the #2 carb to the vacuum port on the petcock? sometoimes people hook up one of the fuel bowl vent hoses there instead, no vacuum comes from the two fuel bowl vent tubes.

Yup, got the correct hose connected. And the fuel line already has a clear filter installed in it. How do you switch the petcock from Vacuum to PRI?? Actually I am at work asking this right now and if I look at it it might be obvious but I thought I would ask anyway

Originally posted by duaneage

Are you sure the boots are not cracked and leaking very badly? Intake boots between the carb and head can separate from the aluminum flange and cause real trouble.

The boots did not appear to be cracked. While they aren't the most compliant in the world they seem pretty soft. I replaced some of the clamps and the ones I didn't replace I shimmed up so they would be a little tighter.

**duaneage** · 04-22-2005, 09:19 PM

The petcock has three positions
On, RES and PRI

Use PRI

**kent** · 04-23-2005, 03:01 PM

I had the same problem on my 81 550L, I had the carbs off several times and went over and over them until I thought I had worn out the screws, come to find out some dill rod had it apart, and removed the carb boots then reassembled them with no O-rings, I installed new O-rings from my local ACE hard ware at 87 cents apiece and the thing now runs great, might be something to look into

**duaneage** · 04-23-2005, 03:09 PM

The o-rings used are a special type that resists gasoline and more importantly, the heat of the head. I recomment using the OEM rings since they are only 4 for 7 dollars at the dealer, not a princely sum.

**bradleymaynar** · 04-23-2005, 03:50 PM

Facing the petcock the settings are:

res..pri
....on

Brad tt

BTW there is no "off"

**Anonymous** · 04-23-2005, 09:14 PM

Originally posted by kent

I had the same problem on my 81 550L, I had the carbs off several times and went over and over them until I thought I had worn out the screws, come to find out some dill rod had it apart, and removed the carb boots then reassembled them with no O-rings, I installed new O-rings from my local ACE hard ware at 87 cents apiece and the thing now runs great, might be something to look into

I replaced the o-rings with some new ones from the Suzuki dealer. So I know that they are there.

**Anonymous** · 04-24-2005, 10:15 PM

Many of us had the 'retreating choke knob' problem. Here's how I handled it for most of the 7 years I had my first 850:

Left hand -- pulls the clutch in.

Right hand -- pulls the choke up.

Right elbow -- hits the starter button.

You'll get the hang of it.

Meanwhile, try getting the bike fired on ether. Most of these bikes 'inhale' through a port accessible under the seat (assuming you're using a stock airbox). I'm not sure why, but more than a few engines need a wakeup jolt or three after hybernation.

Other than that, it sounds like you need an experienced troubleshooter. Perhaps the dealership didn't get things quite right, also.

**Anonymous** · 04-26-2005, 10:11 AM

I think I have decided to take this to a bike mechanic. I can work on cars pretty well but these motorcycle carbs have me pretty befuddled :roll:

**Anonymous** · 04-27-2005, 12:40 AM

check and make sure your idle screw isn't backed all the way out...

**Anonymous** · 05-11-2005, 03:11 PM

Originally posted by brveagle

check and make sure your idle screw isn't backed all the way out...

One problem was the idle screws were all the way out.... but that wasn't all :roll:

The fuel line was too long and had kinked....
The carbs were way out of sync.... the guy who rebuilt them didn't sync them.....
One of the bowls had a crack in it and was leaking....
The brakes system needed an good cleaning.... they were hanging up and dragging.....
etc. etc. etc.

I have gotten the bike back from the shop and it is running great. I don't even have to choke it to get it started. Oh, and he had messed around with the choke cable enough that it didn't work at all so he pulled one off of a used bike they had sitting in there and replaced it for me at no cost

Now i'm off to start enjoying my first motorcycle 8)

**Planecrazy** · 05-11-2005, 04:28 PM

OK, first ... disregard everything you've been told about setting your petcock to prime. You have a 1980 model (just like mine) and your petcock doesn't even have a lever, nor is it possible to set it at all. ALL the 1980 GS's had this lousy petcock design, and unless yours has been retrofitted with a conventional replacement the only way to get the gas flowing is to apply vacuum to the vacuum line going into the petcock.

Second, with regard to needing three hands and only having two ... there is a electrical cable that comes out of your clutch lever and goes into your headlight housing. If you open up the housing and trace that cable you will find two wires coming out of it. Pull the connectors in the housing off the two wires and jump them together ... that will bypass the switch that prevents the bike from starting without squeezing the clutch. Once you've done this you can hold the choke cable up and press the start button without needing a third hand. A lot of people leave that safety switch bypassed for convenience ... your choice.

Third, these bikes are notorious for being hard to start when cold, and your choke needs to be pulled as far as you can. On my 550L, I have to crank it "forever" before it will start cold, even after a professionally rebuilt carb job. It's always been that way.

Good Luck ... it sounds like the bike is on the verge of coming to life!

Steve 8)

**Planecrazy** · 05-11-2005, 04:31 PM

Oops, in between starting my last response and sending it you posted your success! Great news!!

Even nicer is the fact that you have the only 1980 GS550L I've ever heard of that starts easily! Enjoy it!!!

Regards again,
Steve 8)

**Anonymous** · 05-15-2005, 01:04 AM

I am enjoying it

It runs nice, rides very well, and is a blast to ride

I just gotta figure out why the horn doesn't work... I probly forgot to hook something back up :roll: LOL

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