Hey,

New to the forums (second post) but I've lurked for a while and read a LOT of info on the idle issues that seem to plague the GS500. I just picked up a 2006 GS500 with about 6k on it. The main issue I'm facing is that either the bike wants to die or shoot up to 4k rpm. Here's a common scenario: I'll start it up (full choke is the only way it works), and it will almost immediately jump up to 4k rpm. I'll let it warm up for a bit (1-2mins) at 4k, then start to dial the choke down. If I touch the choke before that, it will die. Even at 2 mins, the bike wants to die when i get it half choked. All in all, it takes about 5 minutes to reach no choke. Then it will sit at around 1200 rpm. Problem is, it likes to dance. Needle will jump 1-200 rpm in either direction. I'll let it warm up another 5-10 minutes like this and then take her out. If my idle is set to 1200, the bike will stall at every single stop. I adjusted the idle up to 1500 rpm with the same result. At 1700 rpm, it won't stall and die on me while riding, but once I hit 2500 rpms (neutral or clutch in), it will jump to 4-5k rpm and stay there. After 20 minutes total run time, it will jump no matter what from 1700 rpm to 4-5k rpm until I adjust the idle back down. Once idle is reset to 1200, it is happy to sit there... but start riding again and it will die on me at the next stop. So I'm either stuck with proper idle and having to restart the bike at every single stop (or even extended periods of pulling in the clutch), or dealing with 4-5k idle where I will usually just feather the brake and clutch playing a delicate balance game to keep it at an acceptable rpm.

Here's my plan (if anyone has any input, please let me know):
Check and clean throttle cable (highly doubt this is where my problem is... no visible kinks)
I've done a very brief check for vacuum leaks and did not find any (still new at working on motorcycles though, so I could be missing it, I'll look again)
I'm going to take it apart and check the valve clearance. I've already got a shim tool and measuring tool.
While it's pulled apart, I'll check for all of the gaskets and proper sealing.
I'm hoping this will show me where the problem is, however, I do plan on upgrading a few things eventually and might just take the plunge earlier than expected. I do want to throw in a K&N lunchbox and get it rejetted so it will run a little richer. Will throw on a new exhaust too, but that's not a priority. Right now, I just want to get her running smooth.

(I use way too many parentheticals when I type)

Hi, Supa and welcome to the forum!

All I can say here is that I had almost the same issue with my bike, although it didn't die that often. My solution was cleaning and syncing the carbs, after that was done it worked like charm.

PS: I also turned the mixture screw 3 turns out.

Hope this helps 

Tight exhaust valves probably

Lets see, a 2006 GS500 with 6,000 Miles on the clock, the bike is 8 years old, divide 6000 by 8 and you get...750 Miles a year.

The bike has clearly sat a large part of it's life, MMO or Sta-Bil should have been added to the fuel during the time it sat idle...clean the carbs 

So... The bike is in pieces now. There are way too many hoses and cables!

Carbs looked great.. Aside from weak screws holding down the float bowls, no problems. Clean as can be. I took the opportunity to adjust the mixture screws while I had it off the bike.

Took off the valve cover since I had easy access and found that the 2 front valves were rubbing on the shims. The other 2 were right at .03mm. Those things were stupid hard to get out while still on the bike. The shim bucket slots were on the backside making it near impossible to pop them out. Had to create a little rubber tool to spin the buckets.

Picking up new shims tomorrow if the shop has em. I'm hoping this will fix all of my idle issues.

Let us know how that works out for you. I took mine apart last week and the clearance were LE: .5 RE: <.02 LI: <.02 RI: .04
Don't know when they were last done but I swapped them out but haven't had a chance to run it yet because I'm waiting on an exhaust.

Quote from: Supa on November 09, 2014, 09:22:07 PM
So... The bike is in pieces now. There are way too many hoses and cables!

Carbs looked great.. Aside from weak screws holding down the float bowls, no problems. Clean as can be. I took the opportunity to adjust the mixture screws while I had it off the bike.

Took off the valve cover since I had easy access and found that the 2 front valves were rubbing on the shims. The other 2 were right at .03mm. Those things were stupid hard to get out while still on the bike. The shim bucket slots were on the backside making it near impossible to pop them out. Had to create a little rubber tool to spin the buckets.

Picking up new shims tomorrow if the shop has em. I'm hoping this will fix all of my idle issues.

Quote from: Supa on November 09, 2014, 09:22:07 PM
Carbs looked great.. Aside from weak screws holding down the float bowls, no problems. Clean as can be. I took the opportunity to adjust the mixture screws while I had it off the bike.

Clean bowls are a good start, clean pilot jets and passages are what counts, check the pilot jets and blow out any passages with compressed air while it's apart. I have never ran across a plugged main the hole is larger. Pull the pilots and blow air down where they screw to the carb body, pull the idle mixture screw and blow air down that hole too, I bielive there is a spring under the idle mixture srew? IRCR<<< IReallyCan'tRemember

There's a spring, a washer, and an o ring. The spring maintaines pressure so the idle mixture screw doesn't loosen itself out. The o-ring is your biggest worry.

I cleaned just about every aspect of the carbs including jets and mixture screws, not just the bowls (although those were a good indication of the rest of it). Pretty sure the previous owner cleaned the carbs thinking that might be the issue with the idle. I bought it knowing this would be something I would have to figure out. Given that I couldn't find any deposits, failing gaskets, or plugs in the jets, I'm leaning more towards the lack of clearance on the exhaust valves being the culprit in my hanging idle.

I just picked up a pair of shims for $20 each... seriously... wth? Called every single shop within an hour drive and only one had any 29.5mm shims. Every other place would take at least a week and Amazon would take almost 2 weeks. I need the bike running again by the weekend since the exhaust on my truck decided to take a crap and a buddy of mine will need a couple of days to weld it and remount it. Gotta have some form of transportation... and I won't be caught dead in my wife's vw beetle.

We'll see if I have time today to drop in the shims and put her back together. I'll provide an update when she's up and running again

Anytime I hear "Previous Owner" I cringe, I have spent many an hour chasing down their follies 

So the first shop that sold me the shims sold me the wrong ones (and at $20 each). Picked up the right shims yesterday and got them in. They're at 0.1mm gap now which I think I'm ok with. I know .08 is the max recommended, but I hear a lot of people running upwards of .13 and running healthier.

Reassembled valve cover after checking the timing chain, dropped the carbs back in, and put the air filter back. It was at this point that I realized I had no idea where the hose from the upper T was supposed to connect. I spent a good 20 minutes looking over everything trying to figure it out only to realize that it doesn't actually connect to anything and is simply an overflow.  Reconnected the fuel lines but had to cut them about 4 times. I cut the On line when I originally removed it as it would not come off the petcock and looked pretty ragged. Getting that line back on was a hellish nightmare. Every time I was just about to get it on, the hose would split at the end. Once that was on, I realized the res line had a small cut in it by the tank petcock and had to cut and reattach that one. At this point, my lines are so short I might as well get new ones.... no room to get in there and easily work on them.

With everything back in place, I opened the tank petcock and let the fuel flow. I had it on Res and everything held just fine. Then I turned it to Prime and fuel was hitting the floor. I checked all my hoses thinking I must have another cut or leak from the lines... but no. It was coming from my carbs... more specifically, my left carb. When I had the carbs out originally, I had to drill one of the screws out since the previous owner ('bout ready to TP his house) cross threaded it. I forgot to get another screw for that one  So now I get to tear it all apart again just to put one screw back in. Moral of the story: check and double-check your assembly or you might end up losing your mind in a fuel soaked garage.

Hey! VW beetles are great!!

I found almost all of my idling issues were resolved with proper valve clearances.
Although I also replaced most of my fuel line (I need to finish that job), and cleaned out the jets.

I bought new low-pressure 1/4" lawn mower fuel lines at Home Depot.  I bought like six feet or something for a grand total of like 9 bucks Canadian.  They're a beautiful yellow.  They're a bit of a tight squeeze  - I think the hoses are 7 mm and 1/4" is 6.35 mm - but they work great.  I cut them down using the original (nasty) hoses, with like 2 to 4 inches of extra for easier assembly/disassembly. 

Finally done! Replaced my fuel lines, fixed the missing screw, and reassembled. Started right up and dropped choke after 30 seconds. No problems there. I let it run for a few mins at 1200 rpm and then turned the throttle a bit. At 2k rpm, I started getting a little knock and rpm would drop a little with each knock. Not sure if it's the valves or not. It was really low on oil before I started it up, so I added enough to fill. I shut it down since I don't want to cause any damage if it is the valves.

When I put in the new shims, one of them went in really easily which shocked me a bit, but showed no signs of problems with a couple turns. Clearance is now between .1 and .13 on the exhaust valves. Think that's too much? Any ideas what the knock could be? It seems to go away at higher rpm, but maybe I just don't notice it. It is also not constant/regular intervals.

Fix one problem and create another.

Someone had this problem recently I think (or I found an older thread while doing research), and Buddha implied that it's a lean misfire.
Happens to me sometimes, too, now I don't really worry about it.

So I decided to start it up again yesterday after letting it sit for a day. Full choke to start, ran on full choke for 30 seconds, then choke off and she idled perfectly  . The knock I was hearing was very very faint this time, but still there at 2k rpm. I decided to take it for a quick 10 minute ride to see if it would idle while riding and to see if the knock was causing any other issues. Bike ran like a champ the whole way, never died and had no issues from the knock. Got it back into the garage and the knock was completely gone

Got a pair of stands over the weekend and was finally able to get the tires up off the ground... and wouldn't ya know it, both front and rear brakes are dragging a bit. Not a lot, but enough to notice and enough to give me another project. I knew this bike would come with a few issues, I just didn't expect to find so many so fast.