Problem: Bike won't idle unless choke is on

[Splash]

Yesterday I filled the bike up with the usual hi-grade gas at Esso and drove home.  Then right before work I suite up and start the bike... Every thing's fine then about 30 secs later the RPMs drops from 4000 to 1200...   I try to turn the choke off and the bike stalls.  I start it again and it will only work with the choke on.  I didn't take it to work.  This morning, I tried to start it again, it still only idles if the choke is on.  The I tried to give it gas... a puff of black smoke comes out of the pipe.  So I try it again, every time I give it gas, big puff of black smoke...

There's no weird noise or anything but when I let it run a few min, there was a definite weird smell... not burnt or anything... just weird.  

Does anyone have any idea what the first thing I should check?  Plugs? Gas? Oil?

Thanks for any help.

BTW, the bike is not modified in any way

[davipu]

check your idle screw and see if it backed out a siginificant amount.  how dirty is the airfilter?

[ponchopirate]

I had a related issue with my bike.  Pull your spark plugs and check to see if you're running too rich or too lean.  When I started having issues my left spark plug was fouled black.  It ended up that one of the washers inside my left carburetor had unseated its self and made the whole thing run really rich, forcing me to open the choke up to keep it from dying.  The throttle response was also terrible.

[Splash]

Thanks..

Well tonight I went out and tried it again... Same thing... So I went for a little spin around the parking lot. There's no lost of power or anything... It's as if there's nothing wrong..... until I stop then the bike stalls unless I put the choke on...  I also noticed a little wet spot on the ground... it's gas and it's coming from the carbs (I'm guessing)



There was a little drip of gas where I circled.


Then I took the spark plugs out... here's what they look like



I also took the air filter out and it doesn't look dirty or anything, so I don't think that's the problem

I also noticed I'm a little short on oil,  it's lower then the dipstick but when I run the bike, there's enough oil to register on the dipstick... I'm going to go buy some oil tomorrow morning.

I also noticed that I got a little piece of plastic broken between the carbs... The tube goes nowhere though... just dumps out of the way.



thanks for your help

[Narcissus]

I have the same problem, and it was just a matter of adjusting the idle screw. But even now its a bit finicky so I'm gonna try what was suggested above, thanks!!!

[ponchopirate]

Maybe it's the lighting but the top picture makes your spark plugs look like they're fouled from running too rich (black), but in the bottom picture they look okay.  I don't know... do you have a maintenance manual?  There are picture of spark plugs in various conditions that you can compare yours to.

[my00forest]

that broken plastic piece is a breather hose.
http://www.gstwin.com/images/how_to/fuel%20hose/www_gs500_de_HoseRouting.jpg
where you have gas coming out of the carb could be one of two things. that is a carb bowl drain and there is a screw on the side that allows it to drain so that might have come loose. the other problem that could be going on is there could be some problem with your floats in that side so you might wanna check and see that the carbs are synced and that you floats are working properly. i had the same thing happen to me but there was almost a steady stream of gas coming out. and i had the same symptoms. check on that float by dropping the bowl on that side and see if anything looks funny and you can compare to the other side.
the plug on the bottom looks a little wet is that possibly the one from the side the gas is dripping out of?
fix that hose first and see if that helps then go onto the bowl check

[Recreational_Anxiety]

Try tapping on the sides of the float bowls with a rubber mallet.... floats might be stuck which will definitely cause this condition.

[Splash]

Thanks for the sugestions... I'll try those probably today

he plug on the bottom looks a little wet is that possibly the one from the side the gas is dripping out of?

Actualy yes... the wet plug is the side the of the bike where I noticed gas coming out...   I'll check that out

[Splash]

Here's an update...

So I drained the tank, bought, gaped and installed new spark plugs, took the carbs out and opened the float bowl and looked around, everything looked fine. Re-installed everything and put new gas in there. At first everything worked fine.. then all of a sudden the RMS shoots to 5000 without choke. and 6000 with choke... Not good... So now I have the reverse of the problem I had before...

The next day I played around with the throttle cable and every thing's fine now... Even went for a 300 mile ride...

Thanks for the suggestions

[CBR JOCKEY]

you know that low oil will cause the engine to stall or ride rough....like only enough oil to read on the tip of the stick..