I've had issues with my 07 Gs500 recently where it only runs smoothly with the choke on. Releasing the choke causes it to have a rough idle, it's either too high or too low, and adjusting the idle screw will cause it to hang when revved or come down slowly. The bike only sat for two weeks during the winter before this started happening, previous to the two weeks it was fine.
Today I had about an hour to take a look at it. It won't start without choke, disengaging choke causes it to sputter and die, no mice or anything in the air box, I did notice a clapping sound coming from the right side carb, so I figure there might be a little dirt or something. I plan on changing the spark plugs only after I siphon out most of the gas (exception of the reserve) and pour half a bottle of seafoam in there and run it till I get smoke and then let it sit for 24 hours before siphoning the rest our and replacing it with fresh gas.
Anything else I should look for?
Would be a good idea to check for a vacuum leak.
Mist some water around the carbs with a spray bottle, a dip in RPM will indicate a leak.
This is true. I'll try that tomorrow. It would be hard to imagine with how much work my mechanic had done a couple months ago. But I will indeed look.
Unless he replaced all the lines a leak CAN just spontaneously happen on old rubber.
But the symptoms are all there. Needs choke to enrich the mixture, idle hangs and is slow to return on throttle blip.
It could also be a clogged idle jet or something leaning out the mix, but start simple and work your way up in complexity. No sense taking the carbs all the way apart if you don't have to.
I agree, it's most likely a vacuum leak. And most likely it's at the intake boots interface to the engine.
Quote from: mr72 on February 22, 2017, 10:29:47 AM
I agree, it's most likely a vacuum leak. And most likely it's at the intake boots interface to the engine.
So I sprayed the boots where it meets the engine. Nothing on the left, but when I sprayed the right, on the metal part I got a change in RPMs. It was slight, but it was there. So its the right boot to engine. There doesn't appear to be any cracks or anything. I'm assuming the entire boot needs to be replaced?
The boot might be OK but there is an oring there that may have gone bad.
Is that the same side that was backfiring through the carb?
Quote from: Watcher on February 22, 2017, 10:47:39 AM
The boot might be OK but there is an oring there that may have gone bad.
Is that the same side that was backfiring through the carb?
Well the backfiring was coming from the airbox I found out. Like a puff sound. The right side sound was like a low volume, hard to hear, clap sound.
Just to add a visual, http://imgur.com/M7dgs5x that is the offending part. How difficult is it to replace the O-ring. I really didn't want to go removing a ton of tubes and such (I unfortunately have the California model.) and having to reseat the carbs. I'm just trying to get rid of the bike.
The oring is between the boot and the engine. It would involve removing the carbs, which would involve pulling the gas tank, but I don't think you'll have to disconnect all the tubes and hoses.
Quote from: Watcher on February 22, 2017, 12:22:12 PM
The oring is between the boot and the engine. It would involve removing the carbs, which would involve pulling the gas tank, but I don't think you'll have to disconnect all the tubes and hoses.
I don't mind pulling the gas tank. Its just all the tubes and then the difficulty I had getting the carbs back on. It was a nightmare last time. I think I might just have to sell it as it is.
The airbox is the biggest difficulty with installing the carbs, IMHO, but putting the airbox on the carbs and then putting the carbs in place makes it a lot easier.
Quote from: Watcher on February 23, 2017, 12:01:23 AM
The airbox is the biggest difficulty with installing the carbs, IMHO, but putting the airbox on the carbs and then putting the carbs in place makes it a lot easier.
Yikes - I have the opposite experience. I prefer to put carbs on, then take out the air filter and stick my hand inside the airbox and massage the airbox rubber mouths onto the carbs. I should actually try it your way too.
Cool.
Buddha.
Quote from: The Buddha on February 23, 2017, 06:02:45 AM
Yikes - I have the opposite experience. I prefer to put carbs on, then take out the air filter and stick my hand inside the airbox and massage the airbox rubber mouths onto the carbs. I should actually try it your way too.
+1 that. That's the way that works best for me. Also helps a lot to glue the rubber boots into the airbox so they don't pop out while trying to fit it.
So after I did the Seafoam treatment to my bike, I started it up and got the white smoke. Drained what I could of the Seafoam, drained the carbs, added fresh gas and took it for a ride. It feels a lot better, but does not solve my problem. Warmed the bike up with the choke on, no issues, turned the choke off - got up to 50 mph and stopped at a stoplight. Bike starts to die rev it to keep it from stalling. So it has to be that right side carb to engine boot. Maybe Buddha and Mr72 can chime in as well on this aswell, I won't have to disconnect any of the tubes or sync the carbs afterwards, will I?
Also does anyone know the part number for the O-rings for the carb to engine boot?
Edit: I also just realized the last shop to work on my bike put the carb bowls on backwards. Instead of the drain screw facing outwards, mine face inwards.
Quote from: nuclearfenix on February 23, 2017, 01:29:10 PM
...
Edit: I also just realized the last shop to work on my bike put the carb bowls on backwards. Instead of the drain screw facing outwards, mine face inwards.
I didn't even realize you
could install the carb bowls on backwards...
Maybe they installed the left carb's bowl on the right carb and vice versa?
Quote from: qcbaker on February 23, 2017, 01:50:28 PM
Quote from: nuclearfenix on February 23, 2017, 01:29:10 PM
...
Edit: I also just realized the last shop to work on my bike put the carb bowls on backwards. Instead of the drain screw facing outwards, mine face inwards.
I didn't even realize you could install the carb bowls on backwards...
Maybe they installed the left carb's bowl on the right carb and vice versa?
It seems like it. They are the same jackholes that dropped my gas tank, put a huge dent in it, never told me, and planned on painting it black to match the rest of the bike.... without telling me.
Also I found this http://gstwins.com/gsboard/index.php?topic=46859.0
Tomtampa says he used Urethane or Sikaflex to seal the leak he was having in the same spot. What are the max temp for those or rather which one could be used in that application.
Quote from: nuclearfenix on February 23, 2017, 01:29:10 PM
Also does anyone know the part number for the O-rings for the carb to engine boot?
See this post for some details about o-rings you might need.
http://gstwins.com/gsboard/index.php?topic=71312.msg857877#msg857877
Quote from: nuclearfenix on February 23, 2017, 01:29:10 PM
Maybe Buddha and Mr72 can chime in as well on this aswell, I won't have to disconnect any of the tubes or sync the carbs afterwards, will I?
Not likely.
You just need to disconnect the carbs so far as you can move them away enough to get at the two boot screws. I don't think you'll need to disconnect any hoses or cables at all.
As for syncing the carbs, as long as they were set right before the leak occurred and weren't messed with before getting this diagnosis, they should still be set properly.
Thanks guys, any ideas on the urethane or sikaflex?
Quote from: nuclearfenix on February 23, 2017, 05:30:05 PM
Thanks guys, any ideas on the urethane or sikaflex?
ditto. urethane, and poly are pretty much the same deal.. idk if gasoline would ever even get to these areas, I would try using some red RTV high temp silicone as that's what I always use and have on hand, as a quick fix. and its pretty easy to peel off if you ever wanna do a proper repair.
Quote from: J_Walker on February 23, 2017, 07:03:56 PM
Quote from: nuclearfenix on February 23, 2017, 05:30:05 PM
Thanks guys, any ideas on the urethane or sikaflex?
ditto. urethane, and poly are pretty much the same deal.. idk if gasoline would ever even get to these areas, I would try using some red RTV high temp silicone as that's what I always use and have on hand, as a quick fix. and its pretty easy to peel off if you ever wanna do a proper repair.
Thanks man. Not trying to make it seem like I don't care about the bike, but this bike has been a problem since I got it. Not saying Gs's are bad, but I bought this bike from a dealership 2 years ago in Maryland. I loaded it up into a truck and drove it home. Dealership promised there was nothing wrong with the bike. 10 miles into riding it I start having issues, I call the dealership and they guarantee it had been looked over and it must have been something I did. They refuse to help me. I take it to a mechanic and he took it apart. The carbs were filthy and the rubber pieces were severely degraded among other things.
I've easily dropped 1500 in parts and repairs into this bike (between work I did and what shops have done). Now I just want to switch to a FI bike.
Sorry to hear you had such issues, dealerships can really screw you sometimes.
If you like the GS the Honda CB500F is basically the same bike with new styling and fuel injectors. Great little bike.
Quote from: Watcher on February 23, 2017, 09:38:55 PM
Sorry to hear you had such issues, dealerships can really screw you sometimes.
If you like the GS the Honda CB500F is basically the same bike with new styling and fuel injectors. Great little bike.
b-b-but the GS500 has 487cm^3, and the honda CB500f only has 471cm^3 MUH HORSE POWER GAINZ HOW DARE YOU!
all seriousness, Its my personal opinion that if you've already got a GS500.. don't get another GS500... :icon_rolleyes: Well that's my thoughts anyway, as I have a hard time on the highways around here on the GS...
[don't know if any of these stats are at the wheel, or at the crank]
Hondas 2016 CB500F
49.6 horsepower arrives at 8,500 RPM, with 31.7 lb·ft torque delivered at 7,000 RPM.
Suzuki 2007 GS500F
51.3 horse power arrives at 9,500 RPM, with 30.4 lb·ft torque delivered at 7500 RPM.
Suzuki 2016 SV650
75 horse power arrives at 8,500 RPM, with 47.2 lb·ft torque delivered at 8,100 RPM
tried to find a bike from honda that was close the SV650, in terms of price, and power unless I've missed something.. there isn't one. you can say I have a bit of a fetish for the SV650s power plant.. I had 50x less problems with the SV's engine, then I've had with the GS's engine. guess I got a lemon too.. don't feel bad.
Quote from: Watcher on February 23, 2017, 09:38:55 PM
Sorry to hear you had such issues, dealerships can really screw you sometimes.
If you like the GS the Honda CB500F is basically the same bike with new styling and fuel injectors. Great little bike.
Well it made me feel better to find out that they got sued last year and closed down. I only found out about it when I was looking for a CBR, I noticed that dealership was selling a ton of bikes for really really cheap. But didn't think anything of it because I thought it was a ploy to get people in and sell them a more expensive bike. But nope, they were liquidating. I found out from their Facebook page they were closing and on yelp the reason why. I guess someone with more money than me got screwed and took advantage of the lemon law.
I'm actually looking at a CBR 600RR, It's my dream bike.
I just checked craigslist locally, 2014+ they seem to be going for about 6k used. and my market is over priced.
idk if I have a dream bike though.. there's bikes I'd like to ride and see how they are.. but I can't have nice things, they always end up with holes drilled in them, an stuck in 2 feet of mud.
Quote from: J_Walker on February 23, 2017, 11:11:40 PM
I just checked craigslist locally, 2014+ they seem to be going for about 6k used. and my market is over priced.
idk if I have a dream bike though.. there's bikes I'd like to ride and see how they are.. but I can't have nice things, they always end up with holes drilled in them, an stuck in 2 feet of mud.
LOL.
Yeah, i'm not looking for a recent model. Like 07-09, they seem to go for around 5 - 6k for those years here. Also I think I may pick up so RTV Red tomorrow, But I saw there is Ultra Black that is Oil Resistant. Would that matter at the Boot intake to the engine or should I stick with Red.
Suzuki claimed really high figures for the GS, the reality is much lower.
According to Wiki the GS makes only 40 HP and 26 lb-ft at the wheel.
The CB by comparison is 43 HP and 29 lb-ft according to a dyno run I found on motorcycle(dot)com.
Not much more, but it is there and at slightly lower RPMs.
The Honda felt really good. Seemed more versatile around town and more willing to respond to throttle input without begging for a downshift. Of course that could have a lot to do with the factory gearing.
Liquid cooling is a plus.
If the 90s GSs were "GS 1.0" and 2001+ was "GS 1.5" the Honda would be a solid "GS 2.0"
If the OP does want to upgrade the SV650 is a classic for middle weight sport on a budget.
Still, I'd be remiss if I didn't suggest to the OP a Yamaha FZ07. Those are FUN. Not much bigger but the torque they got from that little twin is quite impressive. Power-wheelies no problem.
I'd put both of these bikes on the radar of any GS fan who wants to upgrade without really stepping up the power.
Quote from: nuclearfenix on February 23, 2017, 11:25:01 PM
Quote from: J_Walker on February 23, 2017, 11:11:40 PM
I just checked craigslist locally, 2014+ they seem to be going for about 6k used. and my market is over priced.
idk if I have a dream bike though.. there's bikes I'd like to ride and see how they are.. but I can't have nice things, they always end up with holes drilled in them, an stuck in 2 feet of mud.
LOL.
Yeah, i'm not looking for a recent model. Like 07-09, they seem to go for around 5 - 6k for those years here. Also I think I may pick up so RTV Red tomorrow, But I saw there is Ultra Black that is Oil Resistant. Would that matter at the Boot intake to the engine or should I stick with Red.
the only difference I know of between the ultra black and red, is the temperature difference.. I just have red because its red, and RED IS A GO FAST COLOR! [the jokes] anyway, black will work I think its "max" temperature is 500F and the red is 650F. so if the black is cheaper, go with it. I promise you that area of the engine won't even see 300F. I've taken spot temp readings all over the engine after traffic, and the only thing that gets super hot is the manifolds.
Sorry to hear about your stealership issues. I had a similar story with my Corolla: when I bought it a few years ago, the dealer told me it had been in a front end accident (i have a feeling they only told me because I already knew via vehicle history report), but that all the damage had been repaired. I went and looked at the car and everything seemed fine. No visible damage, nothing apparent under the hood, car drove fine during my test drive. They told me everything worked on the inside, including the AC. Now, when I bought the car it was March. So, when I tested the heat, it came out warm, when I tested the AC, it came out cool. So I figured everything was fine. A few months down the road, when it shot out, the AC doesn't come out cool. I take it to my preferred shop, and they show me something I hadn't noticed: the high pressure line on the AC has a pinch in it (from the accident) and that's why it doesn't work right. I call the dealership, but they just say "it worked when we sold it to you, must've been something you did". Eventually I got it fixed, but it was a hassle and a half. It was a dealer-only part so my normal mechanic couldn't order the part, I had to go to a Toyota dealer to get the part, and have them install it since I didn't have the tools or experience necessary at the time. Expensive as hell too.
Quote from: qcbaker on February 24, 2017, 06:44:58 AM
Sorry to hear about your stealership issues. I had a similar story with my Corolla: when I bought it a few years ago, the dealer told me it had been in a front end accident (i have a feeling they only told me because I already knew via vehicle history report), but that all the damage had been repaired. I went and looked at the car and everything seemed fine. No visible damage, nothing apparent under the hood, car drove fine during my test drive. They told me everything worked on the inside, including the AC. Now, when I bought the car it was March. So, when I tested the heat, it came out warm, when I tested the AC, it came out cool. So I figured everything was fine. A few months down the road, when it shot out, the AC doesn't come out cool. I take it to my preferred shop, and they show me something I hadn't noticed: the high pressure line on the AC has a pinch in it (from the accident) and that's why it doesn't work right. I call the dealership, but they just say "it worked when we sold it to you, must've been something you did". Eventually I got it fixed, but it was a hassle and a half. It was a dealer-only part so my normal mechanic couldn't order the part, I had to go to a Toyota dealer to get the part, and have them install it since I didn't have the tools or experience necessary at the time. Expensive as hell too.
"it worked when we sold it to you, must've been something you did"
After the dealership (Or stealership, I like that, i'm gonna use that from now on) told me that, I was furious. If i'm on the phone with any other dealership and they tell me that... and I hang up, it can be guaranteed i'm on my way to beat some ass.
Edit: So i've come to the conclusion That the last shop that worked on my bike removed the boots from the engine instead of leaving them on and disconnecting them from the carb side. I used a bit of water to attempt to find the Vacuum leak but wasn't getting anything. Switch to carb cleaner and got dropped RPMs. I switched back to water and instead of spraying it I started pouring it, and thats when RPMs dropped. I carefully poured it on other parts of the bike just to make sure. When the bike cools down i'm gonna put some RTV Red on the metal side and check back in 2 hours to see what happens.
Quote from: nuclearfenix on February 24, 2017, 07:20:29 AM
When the bike cools down i'm gonna put some RTV Red on the metal side and check back in 2 hours to see what happens.
Oh ... boy.
Just replace the o-rings. They are 50 cents each. You don't even have to remove the carbs from the boots. Just pull the airbox and then remove the boots from the engine and replace the o-rings. Put it back together, problem (most likely) solved.
If you have cracks in the boots themselves, then you have to replace them. They are about $17 each IIRC. I had to replace one of mine.
It could be that the hose clamp holding the boot to the carb is loose or that interface is not seated correctly. It's fairly easy to get it to flex to the point where there is a gap around the edge in one spot where you can't see it.
Toss the RTV and fix it right. IMHO. It's not hard. It's a lot more work to fix it wrong and then try and chase down what's still not working.
Those intake boot o-rings are a super common failure in GSs.
I saw your post after I put the RTV on. I did tighten the clamps as they were a bit loose. One of the screws ended up getting stripped as I was tightening them. I'm gonna go out in about an hour or so and start the bike up and see what happens, then do it again in 24 hours. If no improvement then my only option is to replace the o-rings.
Quote from: nuclearfenix on February 24, 2017, 12:40:30 PM
If no improvement then my only option is to replace the o-rings.
You are going to be replacing the o-rings. Bet on it. Might as well order them.
http://www.thisoldtractor.com/for_sale_dr350_orings.html
SPN# 09280-40010
Quote from: mr72 on February 24, 2017, 01:56:14 PM
Quote from: nuclearfenix on February 24, 2017, 12:40:30 PM
If no improvement then my only option is to replace the o-rings.
You are going to be replacing the o-rings. Bet on it. Might as well order them.
http://www.thisoldtractor.com/for_sale_dr350_orings.html
SPN# 09280-40010
Yeah, all this was meant to be a band aid till I got rid of the bike within the next month or so. So I started the bike up with choke on, let it warm up, and turned choke off. It was a little better, but the RTV needs a full 24 hours to cure. So tomorrow i'll change out the spark plugs and then try and run it and see what happens. I'll order those O rings just in case.
Also is it possible fouled spark plugs could cause rough and hanging idle? I believe I did a decent job at sealing the intake boots. But I still getting that low idle, increasing idle speed causes hanging idle.
I've ordered the O rings and plan on going ahead with the repair. But i'm concerned that may not have been the issue.
Fouled spark plugs would cause a rough idle (as if they are badly fouled that cylinder won't be firing). I've never had fouled plugs cause a hanging idle though.
Simple way to check is just to pull the plugs out, have a look and give them a clean with a wire brush and reinstall.
Rough and hanging idle is almost always a condition of leaness somewhere. For me, what finally solved a pesky hanging idle was a thorough cleaning of the pilot jets, getting the float height set to the highest limit (a little over 15mm) and 3 turns out on the air/fuel mixture screws. :thumb:
So i'm having a rough time finding time to do this repair. The O rings came in and I forgot I don't have hex key set to remove some of the hex screws. So, rough estimate, how much do you guys think a shop will charge me to fix it.
Quote from: nuclearfenix on March 01, 2017, 11:24:30 AM
how much do you guys think a shop will charge me to fix it.
If you
just ask them to replace those o-rings and nothing else, probably an hour of labor whatever that is. $80?
If you ask them
to fix it which would include diagnosing whatever is actually wrong with the bike and remedying it, I'd bet a competent shop would do it for $200, including replacing the o-rings you supply as a customer-requested fix regardless of whether they think it needs it.
Make friends with someone on this forum and I bet you can get it done in a half hour for nothing. If you rode the bike to my house I'd walk you through it and be done in a half hour. You will spend most of your time removing the tank and airbox, then reinstalling them.
Quote from: mr72 on March 01, 2017, 01:41:45 PM
Quote from: nuclearfenix on March 01, 2017, 11:24:30 AM
how much do you guys think a shop will charge me to fix it.
If you just ask them to replace those o-rings and nothing else, probably an hour of labor whatever that is. $80?
If you ask them to fix it which would include diagnosing whatever is actually wrong with the bike and remedying it, I'd bet a competent shop would do it for $200, including replacing the o-rings you supply as a customer-requested fix regardless of whether they think it needs it.
Make friends with someone on this forum and I bet you can get it done in a half hour for nothing. If you rode the bike to my house I'd walk you through it and be done in a half hour. You will spend most of your time removing the tank and airbox, then reinstalling them.
...Hey, buddy! :D
$200 isn't that bad. I actually did try looking for someone local on the "Map yourself" thread but it doesn't seem there are many people in VA. Even at that, the one guy I did get in contact with doesn't have his GS anymore and not a lot of experience mechanically on the GS.
So I got the time to remove the airbox and the carbs just to get to the boots. I popped them off and removed the O-Rings (The rings weren't cracked but they were hard as hell, like really stiff), put the new O-rings in and put the bike back together. Took about 2 hours. I warmed the bike up and rode it. Turned the choke off and the RPMs plummeted to around 1k. Adjusting the idle causes hanging or too low of an idle. I cant get it to 1.5k solid.
I will say that the bike seems to run just fine if I leave the idle at 3k. When ever I sprayed carb cleaner on the bike to find the leak (Before replacing the O-Rings) the only area where I got a response was the boots.
Here are some pictures of the boots before I replaced everything. Ignore the red stuff, it's RTV.
http://imgur.com/GnnXkPh
http://imgur.com/BymYJJ7
http://imgur.com/aM2mbyw
The last picture shows a little crack but it wasn't even all the way through, it was just a surface crack.
What else can I look for before I put it into the shop.
Do yourself a favor and don't spray carb cleaner on it!!! :) it can literally MELT the rubber diaphragms that the carbs depend on to work correctly.
Anyway, sounds to me like your problem is the idle mixture is way too lean. Are the access plugs removed on the bottom of the cabs? If so then you should adjust the carbs according to numerous instructions available here but basically the idea is to get the bike FULLY WARMED UP (ride on the road for 10+ minutes) and then tinker with the adjustment screws, start with 2.5 turns out and keep turning out (richer) until the idle speed stops increasing, double-check the hanging idle conditions by revving above 5K rpm and letting it drop, if it hangs at a high idle speed for a few seconds then make it more rich 1/4 turn at a time for both carbs until it stops. If it takes more than 3.5 turns out then you probably need to jet up to #40 pilot jets. Seems most GS500s run best on #40 pilot jets with about 2.5-3.5 turns out, according to reports. Talking about 89-00 bikes here. IDK about the 01+.
Once you get the idle mixture dialed in, adjust the idle speed to 1100-1300 rpm. Anecdotally speaking my bike idles at about 1300+ rpm when it is sort-of-warmed-up (say, 8-10 minutes riding) and after it is seriously warmed up (30+ minutes riding) it tends to idle down at about 900-1000. If I lower the idle any more to try to get the not-seriously-warmed-up idle down under 1300 then it will try to stall when it's seriously warmed up. So there's like this balance you might wind up having to achieve. It's carburetors. Hardly an exact science.
If you have a vacuum leak, or if there is any chance whatsoever you have a vacuum leak, then adjusting the idle mixture is a fool's errand. Fix the vacuum leak first. Same for if you have bad float level or leaking o-rings inside the carbs. Basically idling is very hard for the carbs to do, and it will only do it right if everything is working >95%.
Your idling problem sounds almost exactly like mine was when I got the bike. I would up changing carbs but the fact is all o-rings were hard/cracked/etc. inside the carbs and it had about a half dozen vacuum leaks. Made more sense to start with something more likely to work. In the end I could have made the original carbs work with the same amount of effort but now I have a set of spares :) But the point is, this is kind of ordinary behavior with long service life. If your intake boot o-rings were hard then you can bet the rest are.
Anyway if the bike will idle at ~1K rpm as-is and you want to sell it, then I'd say let it idle at 1K and sell it, warn the next owner that it probably needs o-rings in the carbs and be done with it. It is only like $10 worth of parts but if you're selling the bike, might as well let someone else do the work. Worst case is it runs but once fully warmed it won't want to idle so you will have to nurse the throttle a little bit to keep it running. Like I say, this is what mine did. It would either idle at 4K or stall. I bought the bike in that condition, confident I could fix it. I eventually did but it took a lot of commitment.
Good luck, and I hope you change your mind and keep the bike :)
It's definitely running lean. And adjusting the idle screw is pointless, as adjusting it will either cause a hanging idle or drop too low. When it's sitting idling the idle speed tends to just jump around between 1000 and 1400. At this point I have no idea where the Vacuum leak is coming from or even if there is one.
So you're saying a bad float level or carb o-rings can cause the sporadic idle, Hanging idle, and stalling when coming to a stop?
Quote from: nuclearfenix on March 06, 2017, 04:34:06 PM
It's definitely running lean. And adjusting the idle screw is pointless, as adjusting it will either cause a hanging idle or drop too low. When it's sitting idling the idle speed tends to just jump around between 1000 and 1400. At this point I have no idea where the Vacuum leak is coming from or even if there is one.
So you're saying a bad float level or carb o-rings can cause the sporadic idle, Hanging idle, and stalling when coming to a stop?
By "idle screw" you mean the idle SPEED adjuster, right? Just set it so it idles inthat 1000 and 1400 rpm range and sell the bike if that's what you are planning to do.
Yes a wrong float level or bad o-rings in the carbs can and will cause inconsistent idle. It's running lean, that's why you have a hanging idle. Why it's running lean could be any number of things. You can't diagnose mixture (or fix it) until all vacuum leaks are fixed. So unless you have the patience to work this out by tearing down the carbs and replacing o-rings, set float level, maybe re-jet, then work through the mixture setting, then I'd say your best bet is just to make it run in the range of normal and sell it.
Again I am predicating my input based on your previous statements that your intent is to just get it running well enough to sell. The factory spec is idle 1100-1300 rpm and IME even on my properly running GS500E the idle speed varies from 900-1500 depending on engine temperature (but it doesn't fluctuate while running... it just gradually goes down as the engine warms up). My point here is that a variable idle from 1000-1500 rpm is not really a super bad thing.
If you're going to keep the bike then I'd say get a set of o-rings on hand, new jets +1 sized (at least a pilot jet) and pull the carbs again, put a couple of hours of tinkering time into it and you'll probably wind up with a bike that runs right on the money.
As a point of reference, when I had the top-end rebuild done on my bike the shop mech forgot to hook up the vacuum line from the petcock to the carbs. The first thing this did is cause the bike to die after I rode it about 2 miles, I had to put it on prime. But once I figured out what happened of course then it idled all crazy because it had been adjusted with the vacuum line not connected so it had a huge vacuum leak. The idle mixture screws were zero turns on one carb and 1/2 turn on the other. To get it to run right required about 3.25 turns out on both carbs and that's with #40 pilot jets. Then over the course of about 200 miles of riding I tweaked on the idle speed about 1/8 turn at a time while at stop lights etc. before settling on a setting that results in no hanging idle and no stalling. It's a quirk of old carbureted bikes, I guess. Let's call it "charm". But it requires you to be willing to sort of get to know it in this way to make it run right. There's no way the shop could have done this unless the mechanic commuted to work every day for a couple of weeks on my bike. This is an owner's labor of love. If you're selling, don't bother. If you're keeping, then get set for this kind of relationship with the bike. A fuel-injected bike won't require or benefit from this kind of involvement. It'll either run right or not, and if not then you have to replace parts, not adjust things. That's a whole different kind of interaction with the machine.
I'm using BUNA o-rings. I also have an 07 and I can tell you that you'll eventually need to replace more o-rings as you go along. My intake boot o-rings were very dry and flat. My valve needle seat o-rings are jammed with white fuel crud, causing fuel to slip by and rich mix. My main jet o-ring were flat, dry, and packed with white crud. My bike actually ran pretty good before I replaced them, but after i did i was surprised, it's much tighter. I wouldn't have known how much better it could run until I did it. Luckily, folks out here sent me to this guy, who sells rings for pennies. I paid about $10 with shipping for everything I needed: http://www.thisoldtractor.com/for_sale.html