1980 GS550L won't start when hot

[bobiii84]

I have a 1980 GS550L that I recently picked up from a family member. This bike has had the carbs COMPLETELY cleaned and the intake boots are brand new. I have not adjusted the valves and the airbox is stock. The bike seemed to run fine when I first got it but when I moved it on my truck it started having issues. I had it out in a parking lot teaching my friend to ride when he stalled it and I couldn't get it restarted. I tried to crank it over and ended up wearing the battery down after a while. I eventually got it started by push-starting it. After I got it started I had to keep on the throttle because it didn't want to stay running once it started up. I got it home and let it cool, when I got home it started right up! Once it warmed up I cut the engine and tried to restart and it just cranked. My Grandfather seems to think it's the fuel petcock being fickle but I ran some tests and disagree. First I installed a fuel shut-off valve and cut it off before shutting off the bike. Still just cranked and wouldn't start. Then I took off and dismantled the fuel petcock. Seems fine to me although there is only a tiny pinhole that changes from "on" to "prime" and I was under the impression that prime just dumped fuel in even with no suction. And in regard to Mike of BBG's comment about prime being meant to allow fuel to flow freely, I understand how it's supposed to work but it doesn't. When I turn it I think it just allows a pinhole to open up for air but it doesn't allow fuel to flow cause I sat there and watched it do nothing. Not really sure why that is cause it all seems to be in working order :/ I would love some help with this if anyone can. I ordered a clymer for it and should get it in the mail today or tommorow. Thanks in advance for any help!

 

[DimitriT]

Hard starting when warm seems to indicate you are not getting enough air
or you are getting too much fuel into the motor. Check the air filter.

Are you applying too much choke to the warm motor?

When you say the carbs where cleaned. Who did the cleaning? Any chance
they messed with the float heights? The float heights might also put too
much fuel into the motor.

Another possibility is tight valve clearances. But usually that's a cold start
problem as the clearances loosen up as it warms.

 

[madbikebreaker]

Next time it happens check for spark when its warm. Seems like you have plenty of gas. Could be the ignitor, coils etc. Hot or cold shoudn't make any difference on how th gas flows, but you didn't mention anything about the chock either. Best thing is just be patient work on one area at a time and you'll find the problem. You can also check BassCliff's web site for more info. I'm sure he'll be around soon to give the formal GSR welcome.

 

[bobiii84]

I will check the spark today, actually, I'm gonna go do that now. As far as the choke, I don't use it when trying to restart cause I've never needed to before. The carbs were cleaned by my grandfather who has been working on these bikes for years and I trust him completely as far as they go. And for the air filter did you want me to check to see if there's fuel in there? I don't think there is but I'll check regardless.

 

[DimitriT]

I will check the spark today, actually, I'm gonna go do that now. As far as the choke, I don't use it when trying to restart cause I've never needed to before. The carbs were cleaned by my grandfather who has been working on these bikes for years and I trust him completely as far as they go. And for the air filter did you want me to check to see if there's fuel in there? I don't think there is but I'll check regardless.

When you say you don't need the choke, does that mean you don't use it
even when the motor is cold?

When these bikes are setup correctly you almost always need choke to start
them unless its really hot outside. The carbs normally setup to run lean on idle
(which is why you get that great gas mileage).

If your bike starts cold without any choke then I would look at doing an idle
mixture adjustment (idle drop) first.

Checking the airfilter I just meant make sure its not plugged up. Maybe rinse
it off with kerosene and reapply some light oil. If you've done this recently you
are probably ok. I forget the recommended interval (5K miles I think).

 

[bobiii84]

Yes I use the choke to start it up, just not to re-start when it's already hot is what I meant. I checked the air filter and it already has a little oil on it and looks in good enough shape. I checked the spark from the wires and it seems good. Unfortunately, I was unable to pull the plugs and check them because I don't have my tools here :/ I will go pick up a remover today though. I also tossed some cables on it to boost the battery because it seems to be dying quickly. When I did this I made sure it was hooked up and it STILL acted like it wasn't getting any juice. (Like one turn then nothing) I jiggled the wires to the battery a little and it seemed to work after that. Does this have some kind of relay past the battery that could be acting up? I don't have my book yet so I really don't know. At one point I turned the key on and it acted like it wasn't hooked up to the battery (No lights nothing) Then I jiggled it again and it was fine. I know that's gonna need some attention, but could it be part of my problem? More to come later as I test more. Also, does anyone have a good pic of the igniter and how to test it? I would appreciate it greatly, thanks!

 

[BassCliff]

Greetings and Salutations!!

Greetings and Salutations!!

Hi Mr. bobiii84,

I'm glad you've joined us. Let me start by encouraging you to clean every electrical connection and ground on the entire wiring harness, from headlight bucket to tail light, including the fuse box, ignition switch, that big fat ground cable from the negative battery terminal to the bottom of the engine, all the molex connectors and bullet connectors, everything. Then connect the ground wire from your regulator/rectifier unit directly to the negative terminal of the battery. There are a couple of task lists in your "mega-welcome" that should be followed in order to establish a baseline for further troubleshooting (if you have any problems left after completing all the tasks). In order to do this properly you must take no shortcuts or you will be chasing one issue after another, causing much frustration and inconvenience. With that said, let's begin...

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

 

[bobiii84]

Well I took the bike out today to see if it would die while I was riding it. It ran like a champ. As a matter of fact, when I got it back I turned it off and it started right back up... So I'm going to clean all the terminals and see what happens. Frustrating...

 

[bobiii84]

Well, took the bike out today for a ride lasting about 40miles and the bike ran good. In order to start it, though, I had to jump it :/ When I got back I shut it off and tried to restart. It acted like it was almost stone-dead. I really am at a loss here. I'm going to take the battery to be tested this week with a load and then I guess I'll start looking for a short. Any suggestions?

 

[BassCliff]

Any suggestions?

Yes, The Stator Papers. It's in your "mega-welcome".


Thank you for your indulgence,

BassCliff

 

[Guest]

added for emphasis

added for emphasis

Definitely, check your charging system with the stator papers as suggested

When I got my 1980 gs550L 3 years ago, I had a lot of starting problems. Spent a lot of time "push starting" by drifting the bike and popping the clutch.... until I used the stator papers and discovered a bad regulator. I tried an aftermarket one but still had trouble.

After searching the forums I found information that the oem regulator is a a weak point on these bikes , I purchased a Honda regulator from Duneage (a GS forum member) and no more problems.

 

[bobiii84]

Okay so I realized that my battery was going bad, after a while it wouldn't even hold a charge. I bought a new battery and charged it up. I also tossed in some new plugs and put the old in the bike storage compartment. I wanted to make sure it was charging correctly so I rigged up a multimeter device to the battery that I can watch while I ride. However, I noticed while I was riding that it wasn't at 14V all the time when it was above 4k rpm. When I came back it was at 12.7V so I assume it was charging fine. From what I read, the RR only allows the battery what it "needs" from the alternator, right? This is why I was reading that it wasn't at 14V when above 4k rpm? Just curious and would like some clarification, thanks!

 

[joeninpo]

This sounds very similar to a problem that I'm having with mine. I've replaced a couple of things here and there just to get it to the point where I could really troubleshoot it. I've troubleshot mine down to a faulty ignitor box, believe it or not. I have an aftermarket one on order right now, so I'll let you know how that works out for me as soon as it get here. I know that an ignitor doesn't sound related, but electrical problems in such a small electrical system can affect every part of the system. I'll let you know something this weekend.

Good luck!
Eddie

 

[bobiii84]

Took the bike out again, this time for about 20miles. When it started out it ran good and was charging 13.5-14V when at speed. However, when I got on the highway it stopped charging right because it wasn't even above 13V. I think this must mean that something isn't working right but I would like anyones input that knows. When I got it back it showed 12.7V so I'm confused. I also noticed that when the highbeam is on the blue light on dash is on solid. But when the lowbeam is on, the blue light flickers on and off and sometimes doesn't show at all. Is this indicative of a short? Isn't the blue beam only supposed to show on highbeam? Thanks!