hello all
rejetted the gs and had float problems. fixed the floats to where they are approximately the same and where they are supposed to be.  i still have no power belof about 3K and after the bike warms up and i come to a stop, say at a stop sign or something,  the bike wants to idle a little over 3K. if i adjust       the idle screw a little bit, it will come back down  to around 1500. also if it is idling fast i can let out on the clutch while in gear then pull it back  in and it will return to normal idle.   i can't figure out what it may be that's causing it to idle high.
anyone have any suggestions?
thanks
oldskool

you know my carb does the same damn thing sometimes      i have no idea why. Does yours do it all the time? but i do have power at all my ranges but it was funny last night i rode it on the freeway (1st time) for about 45 minutes and then shut it off and then started it up about 20-30 minutes later and she was bogging down alittle. CRAZY!!! :dunno:

Damn i thought i was all alone on this mine is doing exactly the same thing i mean exactly. Anyone know what the problem is?

Mine too! Whats going on?

Is the throttle cable getting stuck?

turn the idle down alittle, it will stay where you want it and wont rise.  I put my throttle at 3000 for wheelies and then turned it back down and it was doing that.  I just lowered the throttle some more and it stays at 1300 and I dont have to let out the clutch for it to lower.

vacuum leakswill cause this problem-  check the boots that connect the carbs to the engine

i don't believe it is my throttle cable, as i have previously checked that. i will check to see if i have a vacuum leak around the carb boots and see if that may be the problem. will let you all know how it works out.
thanks for the suggestions.
olskool

Pretty much same problem with mine. It runs great now. Not sure what fixed it but heres what I did...
1.Cleaned and rebuilt carbs.
2. Adjusted valves.(Slightly out).
3. Replaced o-rings on rubber intake boots.

I highly suspect it was the o-rings on the intake boots as they were completely flattened.

Derek

My $0.02 :

Mine (no mods but for a couple of stickers) tends towards the same thing, combined with almost un-ride-ably weak low-end power, especially if it's been ignored for a spell.

An attempted carb rebuild at 3,850mi revealed only a very clean pair of carbs, no obvious problem with the carb intake fittings, jets, diaphrams, etc.

Setting the idle low enough seems to help - setting it slightly high makes it a lot worse.

I swapped the plugs for splitfires, it runs a bit better at all RPMS (subjective judgment..).

My conclusion was that the bike is hyper-sensitive to old gas - it ran terribly and did the same thing when I bought it off a couple who'd lost interest in it, and it tends to happen if it's been ignored for a few weeks.  My swipe at keeping it from stalling with bad gas is to crank up the idle, which then fails to come down from 3,000rpm once warm...

Draining the tank of the old stuff down to about a gallon (it didn't bother my wife's CR-V!) and re-filling it with fresh gas helped a lot several weeks ago.  I threw some HEET (nasty stuff that allegedly "removes" water from hydrophilic Ethanol-laced gasoline) in it yesterday and it ran wonderfully today.

My other guess would be a carb synch problem, but I mention this only because it's one thing I've not tried lately and may leave up to the shop.

+/- related - the GS500 feels great and normal unless I've been riding my other bike, a DR650.  The DR's motor drops revs much more quickly between gears and has (relatively) phenomenal low-end torque vs the GS.

For some reason I've had issues like this with all of my I-twin motorcycles.

Things I've noticed to help:

93 octane.  If you can't get it, go to your local municipal airport and buy aviation fuel.  It's 113 or so and usually runs $4 a gallon.  You can mix that half and half with pump gas.  It's leaded, though...I've never had a problem even running it straight but I'm sure that unleaded only text on the guages and caps is there for a reason.

No warm up.  Start bike.  Ride.

Propper, clean jetting.  Even if everything looks shiney and clean disassemble and clean anyway.

Lube all the linkages really well and clean the slides.  One time I had this problem on one of my EX's.  Turned the the slide on the keihin was going up propperly but it was really slow to come back down.

Clean your choke REALLY well.  These bikes don't really have a "choke"...it's actually an enrichener.  Most of you guys have never seen anything with an actual choke...except maybe a lawn mower or something.  Sometimes the fueling and slides on the enrichener can get gummed up.

Quote from: makenzie71
93 octane.
 

Octane is a funtion of ignitability. High octane fuel is a waste in a GS and its relatively low compression ratio.

Quote
No warm up.  Start bike.  Ride.

Not very healthy for an older air cooled engine.

Most often idle problems with GSs is either intake valves going out of tolerances, mangled jetting in the carbs, or an intake leak.

You mentioned that you can adjust it down to 1500 so what happens if you just leave it there?

Have you done the idle drop test?

Once it's warmed up and idling where you want it, if you blip the throttle does it come down gradually or does it drop rapidly and die?  Rpm's coming down slowly means lean, dropping rapidly or dying is too rich.  

With larger jets, you may also have to adjust your mixture screws to idle correctly.

Quote from: JamesG

Quote from: makenzie71
93 octane.
 

Octane is a funtion of ignitability. High octane fuel is a waste in a GS and its relatively low compression ratio.

Quote
No warm up.  Start bike.  Ride.

Not very healthy for an older air cooled engine.

Most often idle problems with GSs is either intake valves going out of tolerances, mangled jetting in the carbs, or an intake leak.

I simply listed what's helped me in the past with my XJ400, EX500's, GS500's and FZ600.

For 500Rider -

The Drop test is just what my '02 GS500 has a tendency to fail.  The odd thing is that it's something that has developed over time and seems to be mitigated my fresher gas.

My results obviously point towards too lean a mixture, but the symptoms appear without having messed with the mixture at all.  I'm at 6,000, and would therefore expect relatively rich-like results.

Two Q's for you or anyone with a well-founded answer:
- does older gas result in a leaner burn than newer gas (I was always lousy in chemistry)?
- If mixture work is the answer, would drilling the mixture adj screw plugs and backing out the screws a touch be a solution or would one have to get serious and go for larger jets?

Thanks!

Quote from: CO_GS500- does older gas result in a leaner burn than newer gas (I was always lousy in chemistry)?

Octane deteriorates over time and, if you go by what JamesG's opinion and use regular all the time, the quality of fuel could be in question.  A lower octane fuel will burn at a higher rate which could increase combustion temperatures drastically.  It's not necesarilly your problem, but spending the extra $.30 a gallon to test the idea wouldn't hurt anything.

Quote- If mixture work is the answer, would drilling the mixture adj screw plugs and backing out the screws a touch be a solution or would one have to get serious and go for larger jets?

If you haven't modified your bike in any other way then your jetting and mixture should be adequate (if they every were).  Problems like this are usually mechanical in nature, not function.

My $100 bill goes down like this

98 down on the mixture settings
1dollar on some slightly worn rings
the last dollar on the carb boots.

Quote from: CO_GS500For 500Rider -

The Drop test is just what my '02 GS500 has a tendency to fail.  The odd thing is that it's something that has developed over time and seems to be mitigated my fresher gas.

My results obviously point towards too lean a mixture, but the symptoms appear without having messed with the mixture at all.  I'm at 6,000, and would therefore expect relatively rich-like results.

Two Q's for you or anyone with a well-founded answer:
- does older gas result in a leaner burn than newer gas (I was always lousy in chemistry)?
- If mixture work is the answer, would drilling the mixture adj screw plugs and backing out the screws a touch be a solution or would one have to get serious and go for larger jets?

Thanks!

CO_GS500:

Not sure if old gas would run leaner or richer.  basically the most volatile compounds evaporate first leaving the less volatile ones in the tank.  I would think this would make it act more like high octane fuel (slower burning) but this is only a guess.  I know mine does not run as well on higher octanes.

Have you checked your valve clearances?  Also, I have heard of the emulsion tubes actually wearing out as early as 5000 miles (on other bikes not the GS).  This would result in an overly rich mixture.  

Adjusting your mixture screws could help.  Check those valve clearances though (they should be Ok but have a look).  I have not had to adjust mine in 10, 000 miles although I have checked them.

If the bike has been sitting for a week, the old gas may have already gummed up the finer pilot jets and passages. For Colorado, you should not have to drill out the plugs over the mixture screws, because of the altitude; the altitude should allow the jetting to be perfect (since it's jetted lean to pass emissions, a higher altitude makes it richer, or perfect (as per Kerry, who is also from CO)). Did you clean out the pilot jet passageways?
And, secondly, are the carbs seated properly, and the airboots over the mouths of the carbs?
Airfilter in place?
No leaks at the headers?

Many thanks 500rider and scratch - The valves weren't touched at 600mi (so they may be contributing), and I just bought the tool to check/tighten the exhaust headers.  I'm planning to do a thorough clean & rebuild during the cold season, unless the cheap and lazy "fresh gas" route holds on.

Galen