High idle

[1980_GS550L]

So a while back I inherited a 1980 GS550L and have been trying to get it to run. When I get it to start, it revs up to about 4000-4500 and stays there until I kill it manually. I also have to manually feed the fuel into the carb bowls because I suspect a bad petcock (which I am replacing). It has been garaged since about 1985-86. The carbs have been cleaned, gas tank coated, I have replaced the intake tubes with the o-rings, and I am still unable to get the bike to run right. I was told it is a vacuum problem but what else can I replace vacuum wise besides the intake tubes? Please help. I a trying to get this to run before spring and can't figure this out.

Thanks for any help/replies in advance.

 

[Steve]

Just below the carbs, between bowls 2 and 3, is a knob that will adjust your idle speed. Try turning it anti-clockwise 1/4 or so.

.

 

[Nessism]

Is the airbox installed? Exhaust pipe condition?

 

[BassCliff]

Hi,

Do you have the airbox installed? Is the throttle cable or choke cable stuck?

In your "mega-welcome" (which you received in this thread) are links to resources like cycleorings.com and the proper procedures for cleaning/rebuilding carburetors. On my little website you'll also find "how to" guides for complete air intake repair and airbox sealing (there must be no leaks in the air intake system), and a host of other proper maintenance and "best practice" procedures. Sometimes there can be more than one cause contributing to a specific symptom. Go through and address each of the items on the maintenance lists. Keep us informed.


Thank you for your indulgence,

BassCliff

 

[tom203]

Yes, as Basscliff said, check cables at carbs; best way is to remove tank and observe the action. You said "when I get it to start..." this implies that it doesn't start right up?? What starting routine do you use?

 

[1980_GS550L]

I have the air box installed and cables are fine. I have tried the adjuster screw and that helps momentarily, however once I do that and open the throttle, it dies.

As far as starting routine, I self feed fuel into the carb bowls through the fuel lines (post petcock) and start it that way. I also suspect a bad petcock, so that is getting replaced.

 

[BassCliff]

Hi,

There should be only one fuel line that feeds the "T" in the center of the carbs.

Have you tried setting up an auxiliary tank? Take off the fuel tank and feed gas directly to the carbs. You must plug the vacuum line. This is my setup when syncing my carbs.

It's almost like setting your petcock to "PRIme". The fuel is gravity fed so it doesn't need the vacuum, the line should be plugged with something. I use a golf tee.

More pictures:

Also see Where Do These Hoses Go?


Thank you for your indulgence,

BassCliff

 

[tom203]

I have the air box installed and cables are fine. I have tried the adjuster screw and that helps momentarily, however once I do that and open the throttle, it dies.

As far as starting routine, I self feed fuel into the carb bowls through the fuel lines (post petcock) and start it that way. I also suspect a bad petcock, so that is getting replaced.

Well, you might indeed have a bad petcock, but that doesn't explain "open the throttle, it dies " stuff. These carbs have a challenging transition point from idle to higher rpm's- the idle/ low speed circuit has to be clear to supply fuel mixture till the main jet takes over. If it starts and takes off with "choke" activated- that's sorta normal: but if you drop the "choke" and it dies/struggles, something is likely clogged.

 

[1980_GS550L]

I have gravity fed it, that is the only way I can get it to start is to add fuel to the line after the petcock and start it from there. BTW, what size are the stock fuel lines on the 1980 GS 550L? I have searched and have found various sizes. I am thinking of replacing the fuel lines

 

[Nessism]

The stock fuel line is 7mm. Made from thin walled stretchy tubing. It's quite different from the typical automotive fuel line that some people use.

 

[1980_GS550L]

Thanks for that info. I will check out the proper thread and see what steps I have or have not done.

I can get the fuel line from one of those websites listed?

 

[cowboyup3371]

Yes you can. You'll get a couple of feet so you'll have lots of extra but that's a good thing.

 

[Suzuki_Don]

You said you replaced the intake boot "O" rings, but did you replace the other "O" rings in the carbs and thoroughly clean the three fuel bleed holes in the throat of the carbs.

 

[1980_GS550L]

To be honest I am not sure. The carbs were cleaned by one of my father in law's friends who works on bikes pretty regularly. I don't know how well of a job he did. I have my suspicions. I know he rebuilt all four but again, not sure of how well he did on cleaning them. I want to remove them and clean them myself but I have never cleaned or rebuilt a carb.

Also, what exactly is "jetting" the carbs? I want to install those pod air filters and was told that I would have to jet the carbs. Does that just mean it allows them to take in more fuel?

 

[Nessism]

Here is the carb rebuild tutorial... http://www.mtsac.edu/~cliff/storage/gs/Mikuni_BS-CV_Carburetor_Rebuild_Tutorial.pdf

For pods the easiest thing to do is get a Dynojet kit for the 1982 GS550M, which has the same engine and carbs as your bike. When you get pods, K&N brand are the best. Some people have reported problems after installing junky aftermarket Emgo filters. Figure on about $250 for pods and filters. It's a lot cheaper to keep the stock airbox, less fussing too.

 

[chuck hahn]

ANTIclockwise??? niow thats funny!! I think its called COUNTERclockwise.

 

[mike_of_bbg]

Either term is proper. Anti-clockwise I find to be used more across the pond; but then it was Steve that said it!.

I think it was asked below - how are you handling the choke? The "choke" on these is actually a fuel enrichment circuit - it increases both fuel and air into the carbs. You should not touch the throttle when starting the bike. As the bike warms up on choke, the RPMs will naturally kick up, and you'll have to feather the choke down to calm them.

If you're going to go pods, Nessism is right - get quality pods (read: APE or K&N, which are almost identical but APEs are much cheaper - no Emgo filter) and get a Dynojet kit. Though I think he meant an 82 GS550M jet kit. In 83 the 550s went to an altogether different and unusual siamese twin carb setup (at least in the U.S. they did). So much the better to get it running right with the stock airbox first if you can.

ANTIclockwise??? niow thats funny!! I think its called COUNTERclockwise.

 

[1980_GS550L]

I have tried to open the link on my computer but it wont allow me to. from what I remember, I used the choke then pushed it in when it ran and the rpms were still high. I then adjusted the screw to get the idle down right. Once that was set, I opened the throttle and it died. I thought it was because I adjusted the screw too low.