Can't keep her alive! Help - 79 GS550; 10k Miles.

[BhBeeZo28]

I just recently became the owner of a '79 GS 550 and I have encountered a problem which is frustrating to non-mechanical experts such as myself.


When I start the bike, I usually have to let it sit on full carb, or close to it, to keep it running at idle. I figured this was just part of the bike warming up. So I take it out for a spin, and about 5 minutes into the ride it gradually starts to idle with less and less rpms while I am stopped, then finally dies. This is with the choke down about half way. So I figured I would just put the choke back on full and continue to ride a bit.

I got it to go around the block about once more, then while I am stopped (with the choke on full still) the bike gradually loses it and dies. I start her up again, she runs for about 10 more seconds, then dies. I continue this process until the bike won't start anymore. I kick-start it, it sounds like it wants to turn over, then it dies again. I keep trying, I get an initial 'rev' as I attempt to kickstart, and then it dies out. Also, as the bike started to lose its power, I got a couple loud pops from the exhaust. Does this have anything to do with it?

Also, on a sidenote, while I was riding around the block in first gear I didn't need any throttle so get going at a decent speed because the engine was running hard from full choke. But none-the-less, I attempt to give it a little throttle while cruising and the bike seems to stutter a bit, not adding any speed to the bike. It actually seems to kill the motor a bit. Yet the other day I had it sitting in the driveway warming up, revved the throttle and everything sounded normal. Suggestions?


Any ideas as to what my problem could be? Feel free to ask for more information as I am sure there is something that I am probably leaving out, but thanks in advance to everyone for consideration.

[Dreef1999]

you have a problem with your fuel to air mixture.
The carburetors are responsible for providing the fuel to the incoming air but are quite sensitive.

Your bike will only run with the choke on so it is probably to little fuel or lean. Your bike runs worse when warmed up which is typical for being rich, which it is because you have the choke pulled.

There is a raft of possible problems and the best solution is to make a checklist and work your way down. When you get to the end of the list then you should have a properly functioning bike that is lots of fun to ride. There is no shortcut.

So when you get the megawelcome go through and check your valves. Remove your carburetor, carb boots, and airbox. Inspect the carb boots and probably replace carb boot o-ring. Inspect and seal the airbox as necessary. Then strip and clean the carbs. Replace all the o-rings on the carbs and reassemble. When it is all back on your bike then you can Carb sync and fine tune a couple of times to get it running just the way it was supposed to be.

Edit: oh and I love my 550 Don't be intimdated by the mechanical parts. Just make sure you use the right tools for the job and don't try to cut corners. Trying to save $10 here and there will just frustrate you in the end.

[Gonzo]

You have a lot of work ahead of you to get it running properly and safely, so if you aren't super keen on getting greasy and turning some wrenches, you may want to rethink your investment. However, if you are willing to put in some work and time, you can turn that thing into a dependable machine. All the info you need is here on this site or linked to it somewhere.

If you make a post in GS Owners introducing yourself, a good fellow by the name of BassCliff will come along and give you a welcome that will increase your GS I.Q. beyond imagination. That or you can use the search tool for "mega welcome" and I'm sure you'll find it. I can't recommend that enough.

[BhBeeZo28]

you have a problem with your fuel to air mixture.
The carburetors are responsible for providing the fuel to the incoming air but are quite sensitive.

Your bike will only run with the choke on so it is probably to little fuel or lean. Your bike runs worse when warmed up which is typical for being rich, which it is because you have the choke pulled.

There is a raft of possible problems and the best solution is to make a checklist and work your way down. When you get to the end of the list then you should have a properly functioning bike that is lots of fun to ride. There is no shortcut.

So when you get the megawelcome go through and check your valves. Remove your carburetor, carb boots, and airbox. Inspect the carb boots and probably replace carb boot o-ring. Inspect and seal the airbox as necessary. Then strip and clean the carbs. Replace all the o-rings on the carbs and reassemble. When it is all back on your bike then you can Carb sync and fine tune a couple of times to get it running just the way it was supposed to be.

Edit: oh and I love my 550 Don't be intimdated by the mechanical parts. Just make sure you use the right tools for the job and don't try to cut corners. Trying to save $10 here and there will just frustrate you in the end.

You guys are amazing. Thanks especially Dreef, this at least gives me direction and an idea of what needs to be done as it was quite intimidating at first. Couldn't thank you enough for the detailed and quick response, makes me really want to stick around the forum. I hope to get back to you guys soon with some good news; as soon as I get some time I'll put a little elbow grease into her and hopefully I'll get her running well soon!

Thanks again and any additional thoughts or tips are still appreciated.

[MisterCinders]

The choke uses its own mixture and relies on the low vacuum of a closed throttle. Trying to ride with choke on is always going to be dicey. Once it warms up, what happens when you kill the choke?

[Dreef1999]

You guys are amazing. Thanks especially Dreef, this at least gives me direction and an idea of what needs to be done as it was quite intimidating at first. Couldn't thank you enough for the detailed and quick response, makes me really want to stick around the forum. I hope to get back to you guys soon with some good news; as soon as I get some time I'll put a little elbow grease into her and hopefully I'll get her running well soon!

Thanks again and any additional thoughts or tips are still appreciated.

like I said I enjoy my 550 and figure you will too.
the gsr have guides to most all of the normal stuff making it incredibly easy to follow and learn. Ask questions about where to buy stuff or to clarify the guides and you will be amazed at how helpful these folks are.

you are going to hate pulling the carbs out of that bike because of the small frame. There are some tips about moving the rear fender but it still sucks

[BhBeeZo28]

The choke uses its own mixture and relies on the low vacuum of a closed throttle. Trying to ride with choke on is always going to be dicey. Once it warms up, what happens when you kill the choke?

The engine slowly goes down and it eventually dies.. Usually within about 5-10 seconds of killing the choke. Any ideas?

Now I can't wait to dive into the carbs hah. I guess it won't hurt to learn a few things. Again, thanks a ton for all help.

[BigD_83]

Carbs may suck, but it's a tossup between carb cleaning and valve adjustments for which is the most rewarding and pays the biggest dividends.

If you do them right the first time, you shouldn't have to have them off much if you run your bike often.

When you have the carbs out and soaking, you'll have lots of time to learn how to adjust the valves.

Welcome to the GSR. Hop on over to the GS Owners forum, and introduce yourself and your bike (these guys like pictures)

[Killer2600]

I hate to say it but clean your carbs thoroughly (disassemble, dip, and everything)

Also don't ride around with the choke on, it's not designed to function that way and any issues or symptoms arising or subsiding from such action are largely inconclusive.

[platinum2]

if it doesnt run off choke the pilot jets are clogged, how good is the air filter?
how about the fuel flow?is your tank rusty?
you might need to remove the carbs blow out the needle and seat with air compressor, and clean the pilot jet with guitar string the thin string

how many miles are on it, how about a compression check ?

[BhBeeZo28]

if it doesnt run off choke the pilot jets are clogged, how good is the air filter?
how about the fuel flow?is your tank rusty?
you might need to remove the carbs blow out the needle and seat with air compressor, and clean the pilot jet with guitar string the thin string

how many miles are on it, how about a compression check ?

Honestly I don't know the answer to any of those questions yet, I have a bit of research to do yet on how to check the status of all those things. What is the best way to go about checking the fuel flow and air filters? - 10k Miles

I think I am just going to start by cleaning the carbs and work my way from there. Is it efficient to clean the valves while cleaning the carbs? I plan on getting to it this weekend hopefully, I have been quite swamped lately but I do plan on getting pictures up and whatnot as soon as possible for everyone.

Again thanks for all of the help, hopefully I'll have an update soon.

[Dreef1999]

Honestly I don't know the answer to any of those questions yet, I have a bit of research to do yet on how to check the status of all those things. What is the best way to go about checking the fuel flow and air filters? - 10k Miles

I think I am just going to start by cleaning the carbs and work my way from there. Is it efficient to clean the valves while cleaning the carbs? I plan on getting to it this weekend hopefully, I have been quite swamped lately but I do plan on getting pictures up and whatnot as soon as possible for everyone.

Again thanks for all of the help, hopefully I'll have an update soon.

When you rebuild the carbs you will have checked the fuel flow and jets by default :-)
After you rebuild the carbs, just follow a guide, you can check if your tank is rusty or gross. Sediment from a rusted tank can be the cause of a clogged jet inside your carbs. A rusty tank is pretty obvious.

I would check valve clearances first because if you need a shim then it will take a few days to arrange one. Then while waiting you have a few days to work on the carbs.
http://www.cycleorings.com/VMkit.html. Carb o-rings
http://www.cycleorings.com/intake.html Carb boot o-rings
You will need a valve cover gasket but wait until you delve a bit before ordering that. You might want or need to group something else to save on shipping. To check valve clearances you will need a feeler gauge you can buy at local auto parts stores for cheap and a big zip tie.

[MisterCinders]

I would check valve clearances first because if you need a shim then it will take a few days to arrange one. Then while waiting you have a few days to work on the carbs.

+1 for this.

If you haven't done these maintenance items, you won't have a baseline for ferreting out problems. Doing these tasks may very well sort out the engine, but if they don't you will have ruled out 90% of the usual villains.

Start with the valve adjustments and strip/dip the carbs.