Put to bed fine, now won't run without choke

[J_C]

I've been trying to slowly get back into riding again - a month ago I got everything running fine, new battery was all it took, ran it around the neighborhood and all seemed a-ok. About a week ago I noticed the battery meter on my bike was reading really low so I put it on a tender.

Today I thought I'd take advantage of the weather so I went to start it up, but it will not run without heavy choke. The moment I hit the throttle, it dies. No idea what could be causing this, when it was running fine 5 weeks ago.

Any thoughts? Thanks GS friends!

 

[hampshirehog]

I would suspect that you have some gumming in the carbs or some muck has settled in there and either way you have some blocked jets. Try running some Redex through there and see if it clears. Always worth a try though you may have to strip and clean the carbs.

 

[J_C]

Thanks for the reply... I sure hope that isn't the case. I drained the fuel before putting it away 2 years ago, and added gas only when I got the new battery and started it up last month. The gas I have in there is only 1.5 months old, and I had put some some sea foam in it, so I can't imagine there would be any gumming or varnish. (Anything's possible of course)

 

[Steve]

Just so you know, adding ANY throttle while the bike is running on "choke" will likely kill it, or at least make it run VERY poorly.

That is because there is not a true choke on these bikes, they use an enrichment system that relies on the high vacuum of a closed throttle to draw air and fuel through the enrichment system. Opening the throttle AT ALL will reduce that vacuum, forcing the engine to try to run on the stock (leaner) jets that it uses when everything is warmed up.

Using the "choke" to start the bike is rather normal. If the bike has not been run for several weeks, you might have needed to put the petcock on PRIme for a few seconds to fill the float bowls before trying to start it. From the limited information given, it sounds like you gave it full "choke", then tried blipping the throttle. The "choke" system was barely working, and only because it draws its fuel from the bottom of the float bowl, but when you blipped the throttle, you were asking it to run on the "normal" jets, which did not yet have the fuel they needed to run, because the fuel level in the float bowls was low.

Just a thought, but that's what you were asking for.

.

 

[J_C]

Many thanks as always Steve. I went back out and made sure to prime the bowls. Then it still wouldn't run without choke. In fact, I needed to keep increasing the choke little by little just to keep it alive. Exhaust was very rich smelling as well. Looks like no riding today

 

[1948man]

Any chance it ever ran rich enough to foul the plugs at some time?

 

[Guest]

Any chance it ever ran rich enough to foul the plugs at some time?

Good point there. I'm just thinking off the top here, are all four cylinders firing (pipes heating up at least a bit before she dies). You could have some bad plugs. Is there fuel getting to the plugs? you might as well yank them all out and see what's happening in there. My thinking is always try the simplest things before jumping into the more complex, like the good advise hampshire dog gave you.

 

[Nessism]

I'd give it an extra shot of Seafoam and see if you can coax it out on the road. Most likely just some minor blockage that will clear up with a little exercise.

 

[Katarat]

Sounds like the pilot jets are plugged

 

[J_C]

Thank you everyone! I'll have a look at the plugs tomorrow, and add some more sea foam after that.

While all four cylinders are firing, it's very possible I may have fouled the plugs. The last few times I have had the bike out it's never been above 5k rpms... all neighborhood riding. I'm wondering if I somehow fouled them and then it wasn't until the bike got cold that it really caused a problem?

Boy, you'd never think that at one time I possessed the knowledge to take this bike down to the frame and back again. I guess all of that schooling wiped out the remainder of my brain.

 

[BassCliff]

Hey Jeff!

Long time, no see.

Did you do a quick test on the charging system? What's the battery voltage like at 4000 rpm?

Yeah, my first thought is also the carbs being gummed up a little bit, even after draining the float bowls. Do the Sea Foam thing like Ed suggests and then get tough on the carbs if you have to. Try some new plugs. Clean all the connections in the charging system and ignition system.

Do you think any critters might have made your airbox their home? Is everything still sealed up properly (intake boots, etc)?

It's good to hear from you again.

Do you remember this ride?

Thank you for your indulgence,

BassCliff

 

[J_C]

Hey Cliff!! Great to see you - And yes, that's the one! I remember that ride well - what a great time

No critters, and everything sure seems sealed up right (no airbox - pods; and boots look ok) I'll definitely keep your recommendations in mind when I get to fiddling around again. Unfortunately I only have a few minutes today to look before heading out of town. So I'll definitely check the plugs. If I have time I'll drain the bowls and see if I can see any telltale signs of bad news. [I'll "save" electrical testing for later - ugh]

 

[J_C]

OK... all my plugs look ok (not fouled), and they're all gapped properly. Some are slightly tanner/grayer, but that's not bad eh?

Only one had a little gasoline on it, rest were bone dry.

 

[Steve]

While all four cylinders are firing, it's very possible I may have fouled the plugs. The last few times I have had the bike out it's never been above 5k rpms... all neighborhood riding.

That really dosn't mean much.

Earlier this summer, I was using my 850 to commute to work in New York. It was about 3 miles from the hotel to the hospital where I worked. Most days, it was very easy to stay under 3000 RPM, probably the most it would see withing a week's time was 4000 RPM. Never any problem with the way it ran. On the weekend, though, I would get it out on the mountain roads in the Adirondacks and "air it out", "clean the plugs", whatever you want to call it, but it ran really great all summer long.

If your jetting is correct, it wouldn't matter if you ran it at idle all day (as long as you provided some cooling).
It should run just fine at any speed or throttle setting.

.

 

[J_C]

OK thanks for that info Steve. Very helpful.

Then that means the only known change between when I put it away and now was that the battery was allowed to run down. I don't think there is a correlation there, so it could be completely unrelated - I'll try and tinker more this afternoon if I get home in time.

 

[240punk]

Just pull the carbs real quick and blow them out. Gotta be it.

 

[GsRocket]

J C,
This is on you 1980 GS1100 right? It definately sounds like a fuel flow issue/ possible air leak and your plugs look pretty lean

When was the last time you checked you manifold O-rings/ have they ever been changed? If you do take your carbs off make sure to check them its only a few extra screws and it could save you a huge headache chasing carb/jet problems.

Second would be how does your fuel flow from your petcock look. i would compare prime, reserve, and ON to make sure everything is flowing right. Sometimes it just needs to be blown out with some compressed air, i have to do mine about every 6 months.

If both of those are fine then dig into you carbs and make sure floats are working fine and jets are not blocked.

 

[J_C]

J C,
This is on you 1980 GS1100 right? It definately sounds like a fuel flow issue/ possible air leak and your plugs look pretty lean

Yeah this is the bike. It does seem lean, doesn't it, considering that was after running on choke.

When was the last time you checked you manifold O-rings/ have they ever been changed? If you do take your carbs off make sure to check them its only a few extra screws and it could save you a huge headache chasing carb/jet problems.

Are you referring to the exhaust gaskets? Those were replaced a few years ago, but pipes have not been removed and I've only put about 1500 miles on it since then.

If you're talking about another set of rings between the carbs and the boots, I don't think my model has those.

Second would be how does your fuel flow from your petcock look. i would compare prime, reserve, and ON to make sure everything is flowing right. Sometimes it just needs to be blown out with some compressed air, i have to do mine about every 6 months.

If both of those are fine then dig into you carbs and make sure floats are working fine and jets are not blocked.

I ran it on both prime and run (those are my only two settings, no reserve) and it didn't make a difference. I can also see the fuel flowing through my clear fuel filter, so I don't think that's the problem. Especially because I can get it up to 6-7k rpms on choke. It's just the instant throttle is applied or the choke is lowered that it dies.

I, having cleaned and redipped these carbs probably 10 times since I've owned it as the result of a now fixed rusty tank, hate working on the carbs. But I think that may be what I have to do. I'm just especially surprised that there may be some blockage because I did put sea foam in the gasoline 2 months ago, and then ran it several minutes to make sure that it got to the bowls. Further, I've not heard of sea foam causing idle problems before, and I've accidentally added way too much in the past and know the funny smell it causes when you use too much. Ugh.

Anyway, thank you for all of your comments!

 

[KEITH KRAUSE]

Sounds like clogged jetting or lack of fuel to the jets, other than the starting circuit (choke).
You should drain and compare/save the fuel in each bowl. Be sure the quantity of fuel is correct and all four are similar in quantity. You mentioned planning to do this. Very easy to check and then you'll know if the problem is fuel related that correct fuel quantity/level is available to the jets. If so, then it would seem that your jets aren't passing fuel correctly. But it seems funny that your pilot jets and main jets could clog up at the same time, and, clog up in only 6 weeks since you rode it around with no such problems.
Pilot jets are smaller and can clog easily but mains take more time to clog from old gas, unless something in the fuel plugs them up. If only your pilot jets were clogged then any throttle opening wider than 1/4 would then transfer vacuum to the main circuit and draw fuel through the mains.
So if you have fuel in the bowls it would seem both pilot and main jets are clogged. I would suspect debris in the fuel for it to happen as you say, unless there are any other details you haven't mentioned. The above is pretty easy to check, even if you have fuel and need to remove the jets you can do that with the bowls removed only. Short screwdriver is all.
Electrical issues can mimic fuel issues too. If you don't have proper voltages at all rpm's then the bike won't accept throttle either. Weak spark can combust smaller ratios of fuel at several thousand rpm provided by the starter circuit but open the throttle and a weak spark can't combust a full fuel flow and it will just gag/stall the bike if you force it.
The bike has sat 2 years, then ridden just once. Electrical issues can sometimes seem odd and not make sense. An electrical system doing nothing then "shocked" after 2 years can do funny things to the battery, ignitor and voltage reg/rec. As part of basic maint' you should read the charging info at this site or your manual and do a test of your R/R and battery first. If the R/R sends out proper voltage at all test rpm's and the battery truly holds a PROPER charge, then the electrical is probably OK. I'm not sure about testing your ignitor and though I don't know much about them, I don't think this sounds like an ignitor issue. Just be positive you have CLEAN/SOLID connections throughout the harness before testing. I know it sounds like a hassle but you know what we say around here...check the basics first. A simple multi-meter will show you voltages and resistance. I'd probably start with the electrical check if you're able. Should be done anyway. Hardest part may be checking all the connections. If all is good, then you know something is up with the fuel filling the bowls or the jets.
PS: Just had this thought to add... float needle valves can easily "stick" with just a little gum from the gas. I never had all four stick at once but if stuck then no fuel or very slow fuel enters the bowls. "Slow" entering fuel can trick you because the bowls may look full upon removal but if the fuel filling the bowl can't keep up with the fuel being drawn out by the jetting then you'll have major fuel starvation. So check them too if you inspect with the bowls off. Put a rag or bowl down first then turn to prime and crank the motor to open up the petcock. Fuel should flow readily at all four valves. I believe your petcock type requires actual cranking to supply vacuum to make the petcock flow fuel. Just putting it on prime isn't enough. So says the factory manual I have for the '80 GS1000. If I'm wrong then disregard that.

 

[J_C]

Keith,

This is tremendously helpful advice. Thank you. I agree with you that it seems odd for everything to suddenly go to pot at the same time.

I am definitely going to run down your list of things to check. You've really gotten me thinking though... The battery was new, and I was checking it every few days via my mounted battery meter, and all of a sudden I checked after a week and it was down to 9 volts. I figured I had let it go too long without starting and threw it on the tender. I'm going to take it off tender, let it sit a few days, check it again and do a load test. That would certainly make sense.

Of course, I will check the fuel levels and everything else as well, including the harness. I became well acquainted with it after going through and recrimping most the connections a few years back.

With all this advice, I certainly ought to be able to track down the culprit. Thanks again, and good hearing from you. Maybe I'll see you on another ride one of these days!