Hey everyone,
I've got a 2008 GS500. I rejetted my carbs a while back (I can hear the collective groan now, sorry >_<), and only went one up on the pilots and mains, and 3 turns out on the fuel/air screw. No washers under the needle, but I did have the slides and needles apart while the carbs were off. The rest of the bike is stock. Bike pulls pretty good, starts up fine, etc, but it seems I can't keep a strong idle. Once the bike has warmed up I've adjusted the idle screw to keep it at 1250rpm, but it seems half the time when I pull up to a red light, it falls flat on its face and idles around 1000rpm unless I blip the throttle a bit. Plus it might be in my head, but I swear the bike seems to be a bit less smooth now.
Anyone have any thoughts? Thanks for all the help. :)
How many miles are on the bike? It might be time for a valve adjustment.
I remember hearing from a member of the group that the idle speed of 1250 is closer to 1500 on the indicator RPM dial. If you have access to an electronic tachometer (most do not), it might be a good idea to double-check to make sure that 1250 is 1250 as indicated on the RPM dial.
Here's what I do...I set the idle to 1500 as indicated on the dial. Yes, it may seem a little higher when fully warmed up, but when the bike is cold, it responds better. Also, given that 1250 is closer to 1500 (as indicated), you may be lower than you think for the idle speed.
Checked the valves while the carbs were off and everything was exactly in the middle of the allowed range for all four valves. I don't have access to an electronic tachometer, but I'll try setting the idle a bit high and see how the bike behaves. Just hoping I didn't end up messing anything up when the carbs were off. Did the cheap float height check with a clear tube and that seemed to be fine too. Gonna do a carb sync on the weekend.
Sounds like you have the basics covered. Report back if you still have issues.
You could be running rich on the low end with a bumped pilot and 3 turns on the fuel screw. What elevation are you riding at? Try turning the fuel screw in to two full turns out and see if that helps.
My elavation is just under 800ft. Is it possible to adjust the fuel air screw without taking off the carbs? The plugs are already drilled out.
It's possible. Just get a 6-8 flat head bit and use it with your fingers to turn the screw. The challenge is to know whether you are actually turning it and know how many turns.
From doing some more searching around the forum it seems that you're right and my fuel mixture screw is set too rich (3 turns). I'll try setting it at 2.5 turns tonight and let you know how it goes. :)
Quote from: skimhitz on May 14, 2012, 12:00:10 PM
From doing some more searching around the forum it seems that you're right and my fuel mixture screw is set too rich (3 turns). I'll try setting it at 2.5 turns tonight and let you know how it goes. :)
It took me a while to figure this out on my 01 after rejet. I bumped the pilots and mains and put the washer under the needle. I ride at sea level and started with the fuel screw out 3 turns......I had to turn the idle up to keep the bike idling right, but she would hang at around 3000-4000 rpm's when she was warmed up.....Had to let the clutch out when stopping to bring the idle down, and then it would idle around 800-1000 rpm's. After a while, I made the connection that I was running rich on the bottom and turned the fuel screws out 2 full turns, adjusted the idle down to 1250 rpm's and she runs alot better now with no hanging idle. Although, I still need to properly sync my carbs to make her run top notch. Glad my suggestion helped :thumb:
My thoughts, in order of how easy they are to check:
1. Vacuum leak (check with WD40)
2. Mixture screws.
3. Valve clearance. I recently bought a GS500 and couldn't get it to idle solidly once it was warm. Sure enough, the exhaust valves were way too tight. Since then, she idles like a dream...well a non-F.I. twin that is well tuned anyways.
Quote from: Juan1 on May 14, 2012, 01:14:09 PM
1. Vacuum leak (check with WD40)
Where would I check this? Is this on the carbs themselves?
Quote from: skimhitz on May 14, 2012, 01:47:30 PM
Quote from: Juan1 on May 14, 2012, 01:14:09 PM
1. Vacuum leak (check with WD40)
Where would I check this? Is this on the carbs themselves?
Yes, direct the spray at different orifices of the carbs while she is idling after she is warmed up. If the idle goes irratic, that is an indicator that there is an air leak at that point. Most of the time, the air leaks are detected at the manifolds where they meet the cylinder head, or the airboot/carb connection(s)
3 turns is just a starting point. The 1250 vs 1000 could be just about 1/2 turn ... however make sure your choke isn't tugging, the air filter isn't clogged, the drain hose on the bottom is intact as well as everything else everyone has suggested.
Cool.
Buddha.