Hi,
I have a 1996 GS500e which will start with the choke on and will idle quite well with it. But as soon as I close the choke it barely manages to idle, and if I open the throttle the bike immediately dies. It will rev with the choke on but then will hover around 6000 rpm even when the throttle has closed again. I've been troubleshooting my GS500 for quite a while now, but have yet to get it running properly yet. I did a fairly thorough carb rebuild recently and the floats are all working very well and I would be surprised if the carb was clogged. I've also recently coated the inside of my tank and put in a better fuel filter so I am guessing that sediment in the carb is not the problem. I've also played around with the idle screw but this has very little effect on the idle speed without the choke. Does anyone have any idea what the problem might be? Any help would be really appreciated, thanks.

Remove the fuel filter to eliminate that as an issue - loads of people have issues with an inline fuel filter, best to be gone from the equation.

It doesn't matter if you cannot think how it could effect anything. Remove it from the equation.

Michael

FWIW: That is how mine acts when i have run out of gas.  (and how mine acts on occassion  )

So i reckon fuel isn't getting to your carbs... but you say floats are fine... maybe a non-persistent problem?  Does this happen all the time?
I assume you are not out of gas.

Valves, or ....

Heck i have the exact same problem... mine is semi-sporadic... and i can't figure it out, so why am i answering the OP?


...... awaiting a solution ......

I've already done a valve check and adjustment, and I think that the fuel filter is not the problem because it is clear and I can see the fuel passing through it at a fairly fluid rate. Also it is getting up to 6000 rpms with the choke on, so enough fuel is definitely getting to the carb. I'll try removing is tomorrow though to be sure.

Make sure the petcock is on PRI(prime),I agree with by passing the filter,if there is one.If it runs fine on PRI,then your petcock is faulty.Save yourself the head ache and upgrade it instead of repairing the factory petcock.
http://gstwins.com/gsboard/index.php?topic=56352.0

Quote from: hugh626 on June 11, 2011, 08:29:58 PM
I've already done a valve check and adjustment, and I think that the fuel filter is not the problem because it is clear and I can see the fuel passing through it at a fairly fluid rate. Also it is getting up to 6000 rpms with the choke on, so enough fuel is definitely getting to the carb. I'll try removing is tomorrow though to be sure.

That makes me think it would be a vacuum leak...

If you have fuel flowing, and you can see it flowing... then it must be getting fuel.  And sounds like your bike (and mine) is idling very lean (hence the choke being the only thing that allows it to rev).  Then must be a vacuum leak?  And a big leak i reckon....

But i could be totally wrong... mine is still broken ya know.

Is your choke cable working well? Mine had the problem that the cable didn't close the choke fully on the carbs. I pulled the slider back by hand on the carbs and the bike idled and revved well afterwards. Just an idea.

I tried checking for an air leak by spraying wd40 around the carb/cylinders connection and the air filter, but it didn't effect the idle speed, so I don't think there is an air leak, and the bike runs completely the same when it is prime, to when it is on reserve. I agree that it is probably running lean but i can't figure out why

try starter fluid more flammable than wd40... one guy had to use propane (eek) to find his leak

Does the bike continue to rev at 6k with the throttle closed and the choke off ? Big air leak if that's the case  (lean condition). Intakes are often the case -on older bikes-(they'll look fine but be dry rotted)-make sure the carbs etc are right before going on a parts buying spree...

When you say you "did a fairly thorough carb rebuild recently"- explain exactly what you did...
Got new parts ( Orings/ flat needle and seat/bowl gasket etc)? Physically remove the jets and clean them out so you could actually see daylight through them? Measured and adjusted the float heights?
Clean every little passage in the carb body with cleaner and compressed air? Flushed out the fuel lines/petcocks (clean the carbs just to pump crap right back in them...) ?

What did you coat your tank with (POR-15 or kreem)?

Try an alternate fuel source  before pulling the carbs back off...

Where are you located Hugh?