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Your main jet is probably way too big, if you have the stock airbox. 125 ought to be as big as you need.

OTOH the pilot jet is probably too small. Stock is 37.5 and you probably need a 40.

A vacuum leak can also make the bike run lean especially at idle.

If I were you I'd pull the carbs, replace o-rings to proactively prevent vacuum leaks etc. (and because it's apart), put 40/125 jets in, then re-adjust. Go from there.

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Quote from: gs500canada on August 24, 2017, 10:49:59 AM
Which O-rings?

All of them.

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I will check the jets he gave me in a plastic bag (the old ones) he might have replaced the pilot with a 40 not sure.

Could be. Stock pilot jet (in the USA anyway) is 37.5 and usually a 40 is recommended.

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I am not very comfortable with replacing jets. And the bike runs quite well when the weather is good. I am hoping to avoid touching the jets.

If it's running lean at idle/pilot then you won't avoid replacing the jets. It's very easy to do. The o-rings will be a bigger job, harder, still easy. Hardest part of the entire job is getting the airbox in and out of the bike.

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Have a new air filter lined up from HiFlo. The one on the bike is a Lil dirty. I will put the new filter in and see how that goes.

It won't have any effect really, at least if it's a cartridge filter that fits in the stock airbox, and even then it would only affect high-RPM/big throttle operation, not idle at all. Air velocity through the tiny little orifice for the pilot jet is not restricted or changed at all by the air filter.

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Why would it take longer to disengaged the choke even in warm weather? Lean?

Yes, it's because it's lean. That jives with a too-small pilot jet. Routine with stock GS500s. You probably will not be able to fix it without changing the jet.

The plugs won't tell you how the idle mixture is alone, they tell something about the mixture on the whole, but if you have stock airbox and 37.5/140 jets as stated, then it's running lean at idle and rich on main jet, so your plugs will report either lean or rich depending on whether it was running mostly on pilot (low revs, 1/4 throttle or less) or mostly on main (WOT, high revs).

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Canada bikes may have had 125/40 from the factory - what year is the bike and was it a US import ?
If so, you need 40 pilots and I am not even sure what a 140 main goes to for set up and why would someone go to 140 from 122.5 ?

Cool.
Buddha.

Quote from: mr72 on August 24, 2017, 10:13:35 AM
Your main jet is probably way too big, if you have the stock airbox. 125 ought to be as big as you need.

OTOH the pilot jet is probably too small. Stock is 37.5 and you probably need a 40.

A vacuum leak can also make the bike run lean especially at idle.

If I were you I'd pull the carbs, replace o-rings to proactively prevent vacuum leaks etc. (and because it's apart), put 40/125 jets in, then re-adjust. Go from there.

when is the last time carb was cleaned?
Aaron

Quote from: yamahonkawazuki on August 24, 2017, 02:34:38 PM

when is the last time carb was cleaned?
Aaron

Bingo

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Quote from: gs500canada on August 24, 2017, 09:33:15 PM
PO cleaned the carbs and installed a Carb repair kit 18-9310 K&L just before i bought the bike.

Unless you watched the P.O. do it, assume it wasn't done correctly. Some people say the carbs are clean, but all they did was spray the outside surface with a garden hose (seriously). Others "clean" the carbs by poking strands of copper wire thru the jets...... but the passageways are still filled with 30 year old gas.

Quote from: gs500canada on August 24, 2017, 09:33:15 PM
Each kit contains float bowl gasket or float bowl o-ring, float needle or float valve assembly and O-rings to rebuild one O.E.M. carburetor body

Not all o-rings are included, but maybe close enough.

If you left out the "little o rings" that go below the vacuum ports on the top of the carbs (plastic top), then the bike will run super lean at idle no matter what jets or mixture adjust you have. It's really easy to lose/forget these and they are not likely included in that kit.

Also the pilot needle o-rings are probably not included in that kit either, but if they are bad you have basically the opposite effect, runs rich at idle no matter what.

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This is great, but the funny part is that in the parts that he gave me I found a 122.5 Main and 40 Pilot   

You'll have a tough time knowing what jets are IN the carbs by looking at the ones that are NOT in the carbs.

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I am a little worried it could be running rich with the jets PO has installed. ...

I will pull the plugs again to check if its running too rich or lean.

Yeah that's a good start. Although I think it's pretty clear from the warm-up behavior that it's running lean at idle, and if you have 3+ turns out on the idle mixture needle then you need to jet up to get it any richer.

And to reiterate, because it may help you get your head around what's doing what, remember the bike runs on the pilot jet at idle and low rpm running with low throttle opening... like maybe 1/8 or so throttle and up to maybe 4-5K rpm under those conditions. It runs on main at bigger throttle openings and/or high rpm. Basically the amount of air flowing through the carb determines (indirectly) the position of the slide/needle, so if there is little air flowing (volume), meaning little air is needed, the slide/needle is down in the main jet closing it and you run on pilot. Once you demand enough air to pull the slide up and cause the needle to come out of the main jet, it runs on main. Main jet obviously is a lot bigger than the pilot jet so it will be the main contributor to fuel flow once it is open at all, pilot jet has very, very little influence on running once you really start moving air.

So the point is your mixture adjustments at the bottom of the carb will only affect idle and near-idle/low-rpm/light-throttle conditions. If you commute for example you probably will run mostly a mix of pilot and little main jet operation, since you rarely really use a lot of throttle or 9K rpms riding in traffic. Probably 90% of my riding is on pilot jet alone, simply because around the neighborhood, cruising on 40mph backroads, etc. doesn't move enough air to open the main jet. The amount you use pilot vs. main will affect how you read the plugs. So for me, if my plugs are black it means my pilot is rich but for someone else on this forum who rides at WOT and high revs like a squid all the time black plugs probably indicate too much main jet. What I'm getting at is the PO might have put big main jets in there in effort to try and get the normal riding to be more rich, when in fact normal riding may mostly be using the undersized pilot jet. So you might not even notice the mains are too rich until you decide to ride like you're in a car chase movie for a bit and then do a plug check.

ive always cleaned them by dunking the
carbs (metal parts ONLY)  IN A  gallon
can of carburetor cleaner a minimum  of 12
hours. usually  longer. might be worth considering if you cant rectify the issues.
Aaron

One other thing to remember is that the bike will run more lean with cold ambient air (44F is cold) than with hot air because of the air density. A CV carburetor essentially meters fuel based on the volume of air, and cold air has more oxygen by volume so the bike will run leaner. If it's already on the lean side of normal when running at high ambient temps then it will likely be quite lean in the cold.

this is true. very true.
Aaron

I'm not thinking the carb is dirty. Change in weather and problems and when the weather inverts problem goes away is adjustment issue. Carbs don't get dirty when in regular use as long as you're putting some decent gas in it and not crap that has twigs and feathers and junk in it like India in the 70's.
Cool.
Buddha.

fair enough my friend, but for piece of  mind, if it were me, id clean it, and jet/adjust to spec. so id KNOW thats been done.
Aaron

Buddhas probably right, hence the name. I've had these problems with my GS, and it turned out to be a tight valve. An exceptionally tight valve to be exact, it was never fully closed.
Carb issues are invariable to temperature, atleast by the seat of the pants dyno most of us have. I dont trust people either, but it sounds like the P.O. noticed a problem and tried to remedy it the way most backyard mechanics would; richen the mixture.
Check your valve clearance. If the bike has more than 8k miles since the last check, its overdue.
To be sure, changes in engine temperature expand the metals the engine is made of, in particular the exhaust valve which are exposed to the most heat. They expand when warm, sealing the gap that is present when the valve lash is too tight (little to no clearance between the valve shaft and camshaft). This presents itself initially as a lean mixture because much of the fuel/air mixture is allowed to go past the exhaust valve before it seats.
The engine heats up faster with a higher ambient air temperature, and slower with a cold ambient temp. You can mess with the carbs, but you are simply delaying the inevitable. Check the valves, thats where the problem is.

Again a tight valve will act up when its warming up. When fully warmed up it would be looser than when cold and hence be good. When cold if it was tight that would result in a cyl not running at all cos it will leak compression right @ start up and never burn.
Of course you may have a bike that runs cool enough below 50F ambient to make its valve tight but over 50 the motor is warmer and acts OK. Except, there is a wide variance in operating temps even at a given ambient. If you sit in traffic for 2 min it may be 100 degrees warmer than rolling steady 50 and sit for 5 mins and you may be far warmer even. So no, I doubt it.
My guess is still - You're just adjusted out of where its comfortable when cold. Most everything else doesn't explain it.
Of course taking it apart to adjust something means you might as well clean and check and readjust everything. Valves are good to do in the window anyway. Like changing your oil. Just a few hours and few $$ - or valves - no $$ if its just a check.

Cool.
Buddha.

Quote from: The Buddha on August 25, 2017, 08:16:42 PM
Again a tight valve will act up when its warming up.

Pretty sure as the bike warms up, the tolerances open up. Someone recently wanted to debate this since the GS has an aluminum head. IME on my own bike, with compression problem from bent valves, it ran fine when cold and would not run when hot.

But I still totally agree with the following:

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My guess is still - You're just adjusted out of where its comfortable when cold. Most everything else doesn't explain it.

My guess is it's on the lean side of good (due to jetting) on pilot/idle and this puts it in the way-too-lean area when it's cold. And my guess is the PO misinterpreted the lean condition on pilot and instead upped the main jet making the problem worse, or at least harder to diagnose.

Quote from: mr72 on August 26, 2017, 06:02:04 AM

Quote from: The Buddha on August 25, 2017, 08:16:42 PM
Again a tight valve will act up when its warming up.

Pretty sure as the bike warms up, the tolerances open up. Someone recently wanted to debate this since the GS has an aluminum head. IME on my own bike, with compression problem from bent valves, it ran fine when cold and would not run when hot.

A valve that is near 0 cold but positive clearance will be near 0 but a larger positive clearance when fully warmed up.
However as it warms up it can get to a negative clearance.

This is because the valve stem warms up faster than the head especially exhaust valve. Exhaust gasses flying past it heat it up a lot faster than the head which has a ton of material even though its aluminum which will eventually heat up and expand much more than the steel of the valve stem.

Cool.
Buddha.