83 GS 550E CARB ISSUE

[Anonymous]

I have an '83 gs550 that was tuned up a year and a half ago, ran great. All of sudden, this week, the bike won't run unless it's choked. Turn the choke off, it dies. Turn the choke off when your movin, it feels like it's not getting enough gas. Question is, stuck float? dirty jet? or something I am missing? Thanks in advance.

[Kabonkie]

I would suspect maybe a dirty jet. The stuck float in your case would be stuck shut and if it's stuck shut, I'd doubt it would run at all.

You can pull the screw at the bottom of the carb bowl and check on how much gas it in the bowl. That will also allow you to see if there is any junk in the bottom as well without pulling the carbs.

I would also suggest looking at the vent tubes to make sure they are not clogged as that would cause it to starve for gas.

If you don't find it and pull the carbs apart, look at the screen under the seat as well to check if it is clogged preventing gas from getting into the carb bowls. As well as the petcock screen in the fuel tank.

Also if there is a fuel filter, check it to make sure it is not clogged, this could prevent gas from getting to the carb as well.

Good luck and keep us posted.

[Anonymous]

Not enough info here to provide a good answer but it does sound like the bike is fuel starved. Your bike has a screen inside the tank on the petcock. If this screen is obstructed, you will get less gas than normal. If there is an inline filter on the bike, you should change it. If you don't use inline gas filters, it is possible that you have debris in the carburetors that is obstructing the interior passageways that carry gas or the jets themselves. There are some other possible causes for running out of gas... next time you feel this happening, open your gas cap. If the venting is obstructed in the cap, you may not be able to draw gas with engine vacuum. Check your vent lines to see they are not kinked or blocked... your float system will not work properly if they are. In other words, gas won't flow in and refill the bowls. Since the problem came on suddenly, it isn't likely that the floats are the issue. A float will stick OPEN and gas will not be shut off... sort of the opposite of what is happening... Floats almost never stick down and shut gas off.

[Anonymous]

Thanks to both of you. I will check all of those later today and post my findings. It's to damn hot to drive a car right now and I just want this thing fixed.

[Anonymous]

OK , all vent lines are clean & clear. All filters & screens are clean & clear I checked gas cap, disassembled, reassembled, cleaned. The bike will run with the choke off now, but will not idle. From idle to about 3400-3500rpm, feels like it is either starving or loading up (need to keep on throttle to keep it idling. From 3500rpm and up, not to bad, but could be better. I did not pull bowls or carbs, and was hoping not to. I do not know where the idle set screw is and don't want to turn what I'm not supposed to. Also, checked the air box, clean/clear. Full tank of gas.

In 2003, repair shop cleaned and went through both carbs. Notes state bike ran perfect afterwards, and did when I got it, up until now. Am I missing something? Are there slow speed and running jets? air/fule mix screws out of adj? Am I missing something? If you need any more info, please let me know.

[gspaul]

As it was running ok before I do not think it is an adjustment problem, you may have a fault with the fuel tap if it's not holding enough vacumn it would have a problem giving you enough fuel at idol, but as the vacumn increases with the rev's it let's a bit more through.
Have a look.

[Anonymous]

Where would the fuwl tap be? I have pulled the tank, checked and cleaned the petcock, checked the fuel line and inline fuel filter. I have good gas flow to the carbs. Checked air filter and airbox (good). Bike will still only run in choked position. Extremely high idle in choke and as soon as you turn choke off it dies. If I keep on the throttle a bit, I can keep it running (that's a pain.) I am not opposed to taking off the carbs, but what problemes do I run into putting them back on? Sync? I would never in a million years know how to do that. And what about parts? Would I be able to get any if needed? (like gaskets,o-rings)


thanks

[gspaul]

The fuel tap & petcock are the same thing, it's operated by vacumn from a hose from the number 2 carby.
The vacumn opens a diaphram that allows fuel to flow only when the motor is turning over, if you have a leak either in the diaphram or the hose the fuel supply will be disrupted.
Also this may sound stupid ,but could your fuel be contaminated.
You could drain it ,and try fresh fuel!
Carb's dont just go way out of sync, check Vacumn leaks around the intakes between the carb's and the head.
Get the motor started & hold the throttle steady at an even idle,or you can use the main idle controle, it's under & towards the rear of the carbs.
Get a spray bottle with some water in it, and spray a mist over one carb intake at a time.
If there is a leak it will suck in the water & you will hear it stumble and misfire.
See how you go!
Oh! And I never use inline filters on a gravity feed fuel system, they can cause a restriction.
There is a filter in your tank ,I think that one's enough.

[Anonymous]

Thanks. So I am clear on a couple of things.....A vacuum leak will cause it to not idle at all with choke off? What if (big what if), I do not find a vac leak? If all my vent tubes/hoses are good and I have good fuel flow, what is my next step? I will be checking the vac stuff a little later. Again, thanks.

[gspaul]

It can happen, but it bother's me that this happend "all of a sudden" often this points to something stupidly simple.
I dont want you pulling your carbs off for no good reason, double check everything.
Does the motor do the same thing with the petcock in the prime position?

[Anonymous]

i HAVEN'T CHECKED THAT YET. I will though. I am completely stumped. Could a mixture screw move by itself? I didn't think it could. Also, On choke, I get an extremley high idle, as soon as I back the choke off it dies unless i keep on the throttle, and then you can hear it starving for gas. Should I remove the inline fuel filter? It's clean and It looks like I get good gas flow through it.

[Anonymous]

One more thing, how should the petcock internals be lined up? There are two small brass "cups" with small holes in them. they were "stacked" with the holes opposite of each other. Should they be lined up?

[Anonymous]

I had my carbs on my gs450L worked on at the beginning of summer...cycle ran great for 200 miles then suddenly..and I mean suddenly sputtered and shut down on my while driving...i could get it restarted but it would just sputter and shut down...would stay if choked...or if throttled...here was my findings.....

1. airbox leak...made sure that it was sealed tight!
2. sprayed carb. cleaner on intake boots...engined rev'd up when I sprayed on the right intake boot..indicated a leak
3. ordered different intake boots(used) and new o-rings.
4. been running ever since.

hope this helps

[Anonymous]

THANKS!! Will check those things and let you know.

[Anonymous]

Since you checked the things I suggested and now the bike will run at speeds over a certain rpm, I think it is time to take the bowls off and see if any jets have become unscrewed and fallen out. The gas in the airbox says that more gas than can be atomized is splashing into the airbox. Unfortunately, it is also running down at least one cylinder wall as well and you should change your oil after figuring this issue out ASAP!