Hi,
My bike will only start without cutting out on full choke, and when I'm riding for the first 20 minutes I have to keep the throttle above 1.5k otherwise it won't idle, it'll just stall.
It also feels a bit 'pathetic' up to about 4k and as you can see on this dyno chart it's running very rich low down.
Is this a mixture screw issue?
Thanks,
T
(http://s66.photobucket.com/albums/h277/th0r0n/GS500EDynograph.jpg)
I am assuming you know how to adjust you throttle, so I will ask you if your carbs are clean.
Has the bike been sitting a while? Fuel will gumm up in our float bowls after a short inactive period.
give some more details about your bike.
If it is running rich and you have not done a carb rebuild/cleaning recently, I would not mess with the mixture screw just yet. A clogged jet could cause a few different symptoms. (I don't think that will make it run rich though)
The little jet being clogged could cause the engine to lag under 4k rpms.
If you have a stock pipe and have not done any work to your carbs, I suggest you take her apart and give a good cleaning. The carbs are easy to rebuild. You could even do it w/o buying rebuild kits and just use the same O-rings and gaskets, but I wouldn't.
good luck and please provide more details. :thumb:
Quote from: 3imo on November 03, 2006, 10:37:01 AM
I am assuming you know how to adjust you throttle, so I will ask you if your carbs are clean.
Has the bike been sitting a while? Fuel will gumm up in our float bowls after a short inactive period.
give some more details about your bike.
If it is running rich and you have not done a carb rebuild/cleaning recently, I would not mess with the mixture screw just yet. A clogged jet could cause a few different symptoms. (I don't think that will make it run rich though)
The little jet being clogged could cause the engine to lag under 4k rpms.
If you have a stock pipe and have not done any work to your carbs, I suggest you take her apart and give a good cleaning. The carbs are easy to rebuild. You could even do it w/o buying rebuild kits and just use the same O-rings and gaskets, but I wouldn't.
good luck and please provide more details. :thumb:
Not sure if the carbs are gummed up or not, I'm not very good with a spanner so I am not sure about rebuilding them
http://gstwin.com/carb_work.htm
Read this how too, and see if you don't change your mind. Hte hardest part is being patient and not losing any parts.
what is a spanner?
Did you try adjusting the throttle?
Quote from: 3imo on November 03, 2006, 10:43:10 AM
http://gstwin.com/carb_work.htm
Read this how too, and see if you don't change your mind. Hte hardest part is being patient and not losing any parts.
what is a spanner?
Did you try adjusting the throttle?
I haven't no, but the bike seems to be fine idling etc when it is warmed up (After about 20 minutes)
sounds like the pilot jets are clogged the orifice on them is tiny-this will show the exact symptons you have desribed will idle ok wont run right between idle and 3-4 k runs fine above that -have your carbs cleaned.
(http://gstwin.com/images/how_to/floatheight/Dscf2431_sm.jpg)
You adjust this knob to bring the idle to 1200RPMS.
If it won't start unless the choke is full on. I would assume it would be one of your small (pilot) jets clogged or something.
anyone else agree?
These bikes are famous for carb rebuilds. It would do you good to teach yourself how to do it. Do you have a clymers or haynes book for the bike?
what is a spanner?
onefastgs500 - you posted as I was posting. Cool, so we agree. :cheers:
tobyR - onefastgs500 would know better then me, so I suggest you clean your carbs. There are hundreds of threads about it. We could help you throught the process. Some here can even tell you where to find the cheapest rebuild kits.
That's great, I'd love to attempt a rebuild.
Any special tools needed? I'm having trouble finding a UK supplier of kits.
http://gstwin.com/carb_work.htm
this will tell you most you need to know. any other questions you got, just ask.
Be sure not to place your plastic parts to soak in carb cleaner. and Be patient. You'll see how easy it is.
Quote from: 3imo on November 03, 2006, 10:49:37 AM...what is a spanner?...
It is, in general, Brit talk for a wrench or other hand tool used to rotate an object or fastener -- but usually a wrench. CLICK HERE (http://www.thefreedictionary.com/spanner)
There are spanner wrenches -- US talk -- they look like a quarter "C" with a hooked end. These are used to rotate an object, like the top steering bearing clamp nut on the GS. You know the one with the four square notches in it? That takes either a spanner or the special socket, or in the case of most of us, a drift/punch and hammer.
The problem with the punch/hammer method is the lack of setting accurate torque.
Thanks Starwalt. :cheers:
I didn't notice he was from Liverpool.
As my boy Srinath would say........
Cool.
Clogged pilot jet - runs with choke but not otherwise = pilot jet.
BTW you check your valves ... that also can be the problem - too tight. But it will tend to stall 3 seconds after startup even with choke usually.
Cool.
Srinath.
The 90 I just got from a coworker has this choke issue also.
In my case it is manageable, though it does like to do the 4k rpm thing. The biggest problem is rolling on the throttle in 1st. Rather than a gradual increase, it does the "jump to 4k" increment.
This makes it hard to perform a smooth start at times. :laugh:
It also likes to stall at lower idles on downhill stops.
I plan to go through the carbs, but I need the riding practice more than another rebuild/repair task at the moment.
Welcome!
Clogged airjet in the intake side/mouth of the carb could cause that, too. Which would cause any adjustment to the mix screw useless.
The GS is typically worthless up to 4k rpm, thereafter, it's better.
Had the same problem when I first bought my bike. It slowly got worse until I had to ride with the choke full on or it wouldn't start or idle. It was also very sluggish off the line and would periodically backfire or die. Took it to the bike shop I bought it from and with one move he felt both of the exhaust pipes and noticed one was colder than the other. He pulled the spark plug and noticed it was fouled. After cleaning it with carburetor cleaner and a wire brush, he screwed it back in and it has been fine ever since. Of course, I check on it every once and a while cleaning it if needed.
Thanks, just my experience.
Hi there,
This is a classic case of a bike that has clogged low speed jets. They are tiny orifices in the jets and when they are clogged, they won't flow fuel.
It's time to take the carbs off, clean everything well, eyeball the jets to be sure they are cleanced out then reassemble the thing.
Guessing won't fix it.
Start with the carb rebuild and you are on the right track.
It's not a hard job, but go slowly and have a good manual to follow.
Oh, yes, good quality tools help too. The heads of those carb screws can be stripped out easily if you use cheap or improper sizes of screwdrivers.
Be careful and let us know how it goes.
Yours,
Todd
Long time no reply!
I did the left hand carb using the existing gaskets and o rings (They were in very good condition) and the float bowl was full of crap.
Had a massive can of Wynns Carb Cleaner that I used the nozzle of to blast the pilot and main jet out with.
I couldn't get the plastic guide out of the middle of the carb, so I had to leave that.
Also, the previous owner had rounded off oen of the float bowl screws on the right hand side, so I couldn't proceed with cleaning that one.
I put the carbs back on the bike, started her up and then a day later realised the vacuum take off line (The bit that goes on the grey plastic sticky out bit on the petcock) was disconnected.
I also had hell getting the carbs back on the airbox.
I threw the clamps away and am using heavy duty cableties instead, they form a better seal than the clamps ever did :D
My mixture screws are set wrong I think though... It'll start up on choke and stall about 20 seconds afterwards if I don't keep playing with the throttle.
But when I ride for a bit, the revs 'stick' at about 4,000 and then work slowly back down to idle.
Cheers,
T