1982 GS550L Bogging Down until Stops Running

[MikeLHeld]

Hello Everyone,

Recently I picked up a 1982 GS550L and it had been running great, in fact I've put 700 miles on it in the first month. I had been running premium until recently when I started having, what I thought to be gas problems.

Its been hit or miss, the bike will tend to bog down right around 4-5grand and then after that it will pick back up again. MOST of the time. Just recently the bike will start to bogg until eventually it won't accelerate or respond to throttle at all. The bike comes to a stop, almost as if its not receiving gas.

And occasionally it wants to die at idle, even though it will usually purr at 1100.

The carbs were cleaned last year, and everything else to do with your usual tune up.

Anyone have any ideas? I originally thought it might be the needle pin/pin needle since it was happening at mid range throttle. But now I'm leaning to some sort of fuel problem.

Any help would be of great assistance.

Thanks,

Mike

[Dave8338]

Air vent in the fuel cap clear?
Do you have an additional fuel filter on it?
Have you replaced the air filter and if so...what with?
Tested the petcock?
Replaced the intake rubbers / o-rings?
All clamps tight and everything sealed up nicely?
How old are the plugs and are they properly gapped?
Getting good spark from the coils?

Welcome to the GSR Fourm!
You will get the answers here BUT...you will have to do some leg work and testing to narrow this issue down.

Basscliff...anyone seen Basscliff?

[MikeLHeld]

First off, THANKS and I do feel welcomed, I am new to bikes. Also with your questions I think I might have narrowed this down. I am able to get the bike started again when I switch the tank (petcock?) over to prime, but not on Reserve or Primary (ON). Naive Question, where might I go from here?

Here are my answers as best I know.

Air vent in the fuel cap clear?
Yes, clean as a whistle.
Do you have an additional fuel filter on it?
No I do not.
Have you replaced the air filter and if so...what with?
Yes, A Oil enriched UNI Foam. Just a bit of oil.
>>>Tested the petcock?
I think this might be the problem, It will only start on Prime. Sorry, if this is a Naive question, because it is entirely.., But where do I go from here?
Replaced the intake rubbers / o-rings?
I do not know, I did not, and was not given much info upon purchase. But all seems to be well.
All clamps tight and everything sealed up nicely?
Everything appears great in this department.
How old are the plugs and are they properly gapped?
Plugs are one season old (200 miles in this owners case) No carbon, and gapped properly. Should I get Iridium?
Getting good spark from the coils?
Great Spark throughout.

Thanks Again,

Mike

[BassCliff]

Greetings and Salutations!!

Hi Mr. MikeLHeld,

With the information you've given about the petcock it sounds like either the vacuum line is bad or the petcock is bad. Replace the vacuum line first, since it cheap, and test the petcock. In the "ON" or "RES" position, gas should flow only when vacuum is applied to the vacuum port on the petcock. Usually you can just suck on the vacuum line and see if fuel flows properly. Be careful because sometimes a failed petcock will allow gas to enter the vacuum line. This is not good either. I would recommend replacing the petcock but some folks have had good luck with rebuild kits.

Moving on, your "mega-welcome" has a couple of maintenance lists of tasks that are pretty much mandatory to restore your classic GS to is former safe, reliable, bullet-proof condition, depending on its initial condition, how long it's been sitting around, garaged or outside, etc. Let's get started.

I just stopped by to welcome you to the forum in my own, special way.

If there's anything you'd like to know about the Suzuki GS model bikes, and most others actually, you've come to the right place. There's a lot of knowledge and experience here in the community. Come on in and let me say "HOoooowwwDY!"....

Here is your very own magical, mystical, mythical, mind-expanding "mega-welcome". Please take notice of the "Top 10 Common Issues", the Carb Rebuild Series, and the Stator Papers. Now let me roll out the welcome mat for you...

Please click here for your mega-welcome, chock full of tips, suggestions, links to vendors, and other information. Then feel free to visit my little BikeCliff website where I've been collecting the wisdom of this generous community. Don't forget, we like pictures! Not you, your bike!

Thanks for joining us. Keep us informed.

Thank you for your indulgence,

BassCliff

[MikeLHeld]

Thanks BassCliff,

I bought this bike from my friend, who didn't know ANYTHING about it. Here's what i gathered from him. He ran the bike in Prime only. He ran regular fuel. Over the last two years he put on 400 miles. He had it "Tuned Up" at the begining of last season. Carbs cleaned, new plugs, new tires, little things....

Since owning the bike as of last month, I've put on 700 miles, changed the oil and air filter, and started running premium. 8.6 to 1 compression, says that should be able to handle 91-93 octane.

I've been finding out quite a bit already. I already have tested the vacuum prior to your post thanks to Dave8338. I removed the vacuum from carb 2. and the fuel line from the petcock to the carbs and sucked in every position.

Results,

No fuel leak from petcock in res/on when not sucking. When sucking (vacuum), fuel flows out in both Res and On position.

Fuel flows in prime both sucking and not.

Does this mean my petcock is in working order?

[DanTheMan]

Thanks BassCliff,

I've been finding out quite a bit already. I already have tested the vacuum prior to your post thanks to Dave8338. I removed the vacuum from carb 2. and the fuel line from the petcock to the carbs and sucked in every position.

Results,

No fuel leak from petcock in res/on when not sucking. When sucking (vacuum), fuel flows out in both Res and On position.

Fuel flows in prime both sucking and not.

Does this mean my petcock is in working order?

Yes it does, no new petcock needed at this point.

[cowboyup3371]

Just from my own experience, you'd be better off going through everything yourself that Basscliff recommends. Yes, you'll probably duplicate work but you'll be happier in the long run knowing for sure what needs to be done. I was told that the carbs had just been cleaned a few weeks before I bought it. Yet, when we opened the bowls to ensure fuel was flowing we found a ton of rust. Once we tore down the carbs, there was no way they had been touched in a long time.

I'm now doing alot of work I probably shouldn't have had the PO actually done what he said. But I now have a peace of mind of knowing exactly where my bike stands and how safe it will be for me to ride.

[MikeLHeld]

Thanks,

I'm not really all that savvy on rebuilding/cleaning carbs, I'll probably have to get that done. I'm trying to rule out everything before I go to this. I'll be reading more on the mega-welcome. Ill see if i can check the intake seals without removing the carbs.

I've been going down the checklist, cleared out any tank vent hole if there was a clog, but it didn't look as if there was one.

The bike is still having a hard time starting up after being killed. Then if I wait a few minutes it will start up no problem. I sort of wish the bike had these problems on purchase.

Mike

[BassCliff]

Hi,

I would recommend sending your carbs to one of the guys here in the forum to have them properly rebuilt. Mr. chef1366 is usually a good guy to send them to, but he jacked up his left hand recently in a little unplanned "get-off". It's really not hard to do yourself if you just stay organized and follow the step-by-step series linked to in your "mega-welcome".

All of the rubber on your bike is almost 30 years old. It's best just to replace it; intake boots, intake boot O-rings especially, replace rubber brake lines with braided stainless steel lines, etc.

Thank you for your indulgence,

BassCliff

[ChicagoBob]

Fuel line?

I had this same problem, and found that the fuel line was kinked. However, from what I've read of this post, it sounds like your problem could be the carbs. I wouldn't believe anything a PO told me.

[Steve]

One other thing to do is to get rid of the "premium" gas.

You can not use the compression ratio as your sole criteria for determining whether you need higher-octane gas, as many newer bikes have ratios over 10:1 and only require "regular" gas.

As mentioned many times, by many people, using higher octane gas does not give you more power. It has fewer BTUs per gallon, so actually give you LESS power, unless you make other modifications.

Back to your problem ... it's possible that your vacuum line to the petcock is leaking, so start with that.

.

[MikeLHeld]

I never trust PO either but he's my previous roommate and I have the reciept from the work done. Now whether the shop took care of the carbs well, that's a whole other question.

However, I removed a portion of the carbs, they look spotless.

I replaced the fuel with regular, cleaned out the vacuum tube and replaced it, and I'm having more success running the bike. Can a bad batch of gas cause problems like I'm experiencing?

[oldgsfan]

I had this same problem on a 1982 Suzuki 650 several years ago. The bike would bog down like crazy, like it was not getting any fuel, and then die. I'd let it sit a day or so and then it would start up, ride OK for a while, and start to cough and sputter and bog down again. Then die, again.

Once, it died on the Oakland Bay Bridge.

Anyway, had the carbs cleaned but the problem returned. Then, replaced the petcock. Never had the problem again.

I didn't have any other symptoms, though. No leaking fuel or anything like that.

[MikeLHeld]

If the problem returns, I'm going to replace the petcock. Its seems fine via tests and internal appearance. It is incredibly difficult to turn, so difficult that I have to use a pliers to change from ON/RES/Prime, I imagine that is not intended.