gs550 stalls when warmed up

[suzi]

Hey to all you fellow gs owners. I,m new to this forum and glad to have found it. I hope someone can help me out! I'll start with a little background first.

I'm a 52 year old dude and own a sweet '79 gs1000. I love it!! I used to have another one also that I bought new in 1979 as well. So am very familiar with the 1000s and usually do all my own service/repairs.
However, I have rarely had any electrical problems and I don't know diddly squat about electronics!
So here is my situation:

I bought a '82 gs550L for my son and it is in almost new condition.
When I test drove it ( For only about 10 minutes) it seemed to run fine. I was told it had a recent carb rebuild. Everything is STOCK on the bike.

When got it home and ran it longer, it started running a bit sporadic/rough. So to be sure, I took apart the carbs and they appeared to have recentally been rebuilt. Didn't seen anything bad.I thouroughly looked at everything and diaphrams looked fine too. cleaned everything VERY well with carb cleaner and comp. air. Put it all back together but didn't make any diff. in performance.
Should also mention here that there was a fair amount of rust in the tank.

Since then I KREEMED the tank and am satisfied there is no more rust; Have rebuilt the petcock;Have replaced intake boots/o rings with NEW set;Rebuilt the carbs myself(again?); installed inline fuel filter; checked all vac hoses and did the WD40 trick around boots. All is good and sealed that I can tell.

Carbs haven't been synced yet but will in a couple days. Will also check valve clearance (soon as I get the tool and vac gauges).

Here is how the bike acts: Starts up perfectly. Battery fully charged and strong. Runs quite rough between idle to abought 3000 rpms, but after about five minutes it idles pretty good and no real hesitation or bogging in mid/high range, which runs strong. After about another 5 minutes, I'll let it idle and then it dies, as if it ran out of gas. When try to restart, it will not fire. This A VERY CONSISTANT account of what happens. I have done this 4 days in a row without any change.

I have checked all the wiring and connections and to me, all seems well.
I have done everything I know to do to eliminate fuel or vac problems and this is why I think it may be an elec problem, especially since I don't know electronics. From what research I've read, I wonder if may be R/R or maybe coil going bad.
Just wonder why it stalls when warmed up and won't restart for about 20-30 min.
Air box boots also seem leak free, but read about "sealing the airbox" Not sure what that means or how important it would be ( I think most critical vac leaks would be from intake boots that mount to eng.)

Please any input would be IMENSLY welcomed!
Doug

[hampshirehog]

Hello Doug. Welcome to the funny farm.

Couple of suggestions. Maybe the petrol cap isn't venting and your getting a partial vacuum in the tank; try running without the cap fitted.

Or try running on prime; your petrol tap may be playing up or your vacuum line could be kinked.

A poorly sealed airbox won't stop your bike from running.

[BassCliff]

Greetings and Salutations!!

Hi Mr. suzi,

You'll want to check out all of the general maintenance documentation on my little website, articles for charging system repair and maintenance, tank cleaning, valve adjustment, proper carb cleaning, etc. You've got a 30 year old motorcycle that probably needs 20 years worth of maintenance. See the maintenance lists in your "mega-welcome".

Let me dump a TON of information on you and share some GS lovin'.

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", "Top 15 Tips For GS Happiness", the Carb Cleanup Series, and the Stator Papers. All of these tasks must be addressed in order to have a safe, reliable machine. This is what NOT to do: Top 10 Newbie Mistakes. 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

[suzi]

thanks for the reply. I checked the cap and the vent is clear. have checked all vac lines, even tried starting it after removing tank (fuel still in the bowls) right after it had stalled. Don't see how it could be any of those. Also forgot to mention that the bike has 13,000 miles on it. Checked all plugs and they look normal tan color.Thanks

[Redman]

Doug,

Next time when it stalls out after running for a while, and will not restart; try poping open the gas cap and then see if starts. This will be a test to see if gas cap is not venting, even if it looks good.

If you still suspect an electrical problem realted to engine getting warm, next time it stalls and will not start, try pulling a spark plug and looking for spark. The signal generator (electronic points) arfe on the engine and subjected to engine heat somewhat.

Welcome to GSR. Good to hear of bike in original condition. Pics of both thw 1000 and the 550 would be nice also.

Dave

PS Where in general are you located?

.

[suzi]

Thanks for your input Dave. As I said before, it wouldn't restart even without the tank on it ( therefore, the cap ). But Now I have a new Problem: I pulled plug wire to test spark (this am when it was cold) and at first there was a blue spark, but a couple tests later I get NO SPARK. Then again back to a blue spark. So what the hell does that mean? To me the spark looked kinda weak, so I pulled a plug wire of my gs1000 to compare and to me, the 1000 spark looked stronger.
My suspicion of electrical problems seems to be a liitle more evident now. I would think either coils or pick up, but I don't know how to tell. I looked at the STATOR PAPERS, but since it won't start (even when it's cold now) I don't really know what to do at this point. If only I knew how to use a damn multimeter!!!!

[suzi]

Oh, I wanted to ask anyone's opinion about Dynatek coils. I saw a pair on Ebay for $125. They're supposed to be more efficient and increase both horsepower and spark. Since I seem to have a spark problem anyhow ( I think anyway) wonder if it would be prudent to get 'em.

How do you tell if a weak or no spark is from bad coils OR from the ignitor pick-up. To me , it would seem a bit unlikely to have BOTH coils go bad at the same time. I tested all 4 plug wires and the sparks all looked about the same. Would this point more to the ignitor?

[Nessism]

Sounds like a carb problem, or petcock/vent problem.

I'd pull the tank and verify the petcock is functioning properly: fuel should only flow when a vacuum is pulled, unless the petcock is set to prime.

When it stalls, open all the carb floatbowl drain screws and see how much fuel is inside - use a catch pan.

Inside the tank, up near the filler opening, there is a small hole inside the vent baffle. When you sealed the tank that hole may be clogged up now which is not allowing the tank to vent properly. Also, loose the fuel filter since they tend to inhibit fuel flow, and make sure your fuel line doesn't loop up in the air on the way to the carbs.

BTW, the stock Nippondenso coils are high quality and rarely go bad. You can try unscrewing the plug caps from the wires and measuring the resistance on them. Assuming good, snip off a tiny piece of the high tension lead and screw the cap back on.

Good luck

[Missile99]

Your ignitor or signal generator may be overheating and failing to work until cool. When you have no spark, is it all 4 plugs?

For your spark intensity: (Would not worry about this until you get the no spark issue figured out.) First check the voltage to the coils. There are several connections before power gets to them and after time usually become corroded. Make sure you have decent voltage, no much more than .5 volts below battery voltage. Don't fear the multimeter, and if you have questions about it's use ask us. Check the primary and secondary resistances (also easy to check with meter) and expose new wire end if nasty. If your spark still sucks then coils suck. That's what it was in my case. They Dyna greens are awesome but not necessary for you yet.

[Missile99]

Oops Mr. Nessism, didn't know I was writing some of the same stuff you did.

Suzi, these people here are as close to experts as you get. It seems like they can rebuild these things with their eyes closed, or while talking sports, or while reading a book.

Simply amazing people here combined with a super site.

[BassCliff]

Hi,

As part of your troubleshooting you may want to remove the inline fuel filter. It is possible that the filter is too restrictive causing fuel starvation. Did you totally disassemble the carbs, dip them in cleaner for 24 hours, and use a small wire to ensure all of the little passages were clear? See the carb cleaning tutorials.


Thank you for your indulgence,

BassCliff

[suzi]

Thanks for all your tips and suggestions guys--greatly appreciated!
I found that hole near tank filler and you were right, it was clogged. I cleaned it.

Still, some things are not adding up to me though. 1--- if it is still carb or vent problem, then what does that have to do when it gets warm, because that is when it was stalling and would not restart. As I had said before, I took the tank OFF to eliminate the vent issue and it STILL didn't restart while warm. When it cooled down about 30 min later, it then restarted fine.

What really puzzles me now is why it won't start at all. Today is the first time that has occured. It does fire right at the beggining for about a second, like it's trying to start.

I do plan on eliminating the inline filter to see if that helps, but I just don't understand how any fuel or vent issues would cause to stall only after warm-up, and restart fine when it's cool (until today)

Maybe I'm not as bright as I thought I was.
Thanks

Thanks

[Nessism]

To repeat myself, open the floatbowl drain screws after it stalls to see how much fuel is inside. That will tell you if the problem is fuel supply related.

[suzi]

UPDATE:

It turns out I guess I'm really not so bright afterall. Just for curiosity I hooked up batt charger on quick charge and within a minute it fired right up. I sware it seemed to be turning over fast enough to start it, But I guess not.

I did drain #1 and #4 bowls. There was about 1/2 to 3/4 bowlful in each I guess--Hard to tell exactly. How much is suppose to be?

Anyhow, after it fired I drove for the usual ten min warmup, and of course, it stalled again and wouldn't restart with or without tank cap.

I then checked for spark and did not get any through the plug wire. Next, I hooked up the charger again (after about 15 min) and it restarted.

So now what?

Thanks again to all of you. I really do feel like an idiot, and can't believe I'm having such a hard time.

[Nessism]

Check the charging system?