2005 GS500f Problems

[cbw0604]

Ok so im new on the forums so hello everyone wish i could post something that would help someone for my first post but im the one needing help so maybe someone on here can help me. I have 05 gs500f when I bought it, it would not run at all just turn over i cleaned the carbs and made sure the jets were clean and everything was clean and then put it back together after attempting to start for a few minutes it started and would run. Well theres still some problems with it since I rebuilt it. So it takes a lot to start it. Like ive watched some vids of people cold starting their gs and mines nothing like it. It takes turning the choke on and turning it over it will start right up but them almost immediately die you have to do this about 15 times and it will slowly run longer and longer until it will run long enough to give it some throttle to keep it running. Another problem thats probably related after it has warmed up enough to sit and idle around 1500rpm if you give it a slight twist on the throttle maybe moving it an inch or so it will sputter a bit and sometime it will die from the sputter. Lastly which I believe is also related is once your ride it for about 10 mins and it gets nice and warm when you pull in the clutch it will idle up to 3000 rpm and sit there until the clutch starts to grab when you start moving again. Maybe this made sense.

[mr72]

maybe someone on here can help me.

Probably. Most likely we help you by getting you to investigate until you figure it out for yourself

It takes turning the choke on and turning it over it will start right up but them almost immediately die you have to do this about 15 times and it will slowly run longer and longer until it will run long enough to give it some throttle to keep it running.

So let me clarify:
It starts fine with choke (good!)
it dies when cold even with the choke on (bad)
Eventually with enough persistence you can get it to run more than a few seconds.

Is that about right?

When it starts with choke, what rpm does it idle? Should idle up to ike 3-4K or more rpms with the choke on even when cold. If not, then the choke is not working right. BTW the "choke" really is a jet that gets opened when the choke lever is deployed. Idle mixture/speed etc. won't impact on-choke operation (much).

Another problem thats probably related after it has warmed up enough to sit and idle around 1500rpm if you give it a slight twist on the throttle maybe moving it an inch or so it will sputter a bit and sometime it will die from the sputter.

Most likely the slides are not coming up. Could be a damaged diaphragm or a number of other things. Could be just a big/bad vacuum leak.

Lastly which I believe is also related is once your ride it for about 10 mins and it gets nice and warm

How can you ride it for 10 min if you can't give it any throttle without killing it?

when you pull in the clutch it will idle up to 3000 rpm and sit there until the clutch starts to grab when you start moving again.

This is "hanging idle" caused by your idle speed being set too high (note 1500 above, that's too high). Normally people do this because they adjust the idle mixture and speed before the bike is fully warmed up. In your case I doubt the bike will run well enough long enough to get fully warmed up anyway, but the 10 minute mark is about where it begins to be warmed up. I usually recommend more like 15-20. Then set the idle more like 1100 or 1200. If it still does "hanging idle" then the idle is probably too lean, which means you are setting the idle "speed" higher to compensate. Done right it'll idle at 1100-1200 rpm when it's good and warmed up with the throttle stop basically closed entirely.

Anyway, I'd say it's entirely possible or likely you have more than one thing going on.

1. hanging idle caused by the idle mixture being too lean and the idle speed being set too high in effort to compensate. You may need to +1 the pilot jet, or maybe the pilot fuel orifice in the carb is clogged or that tiny pilot jet (hey, the thing is only 0.175mm!) is clogged. In any case with your problems I'd suggest pulling the carbs and replace the pilot jets. Put in 20s.

2. Vacuum leak is likely, I'd bet the intake boot o-rings are old and hard and don't seal. Might be other places on the Mk2 carbs that have opportunities to make a vacuum leak.

3. If vacuum leak is not causing the hesitation/stalling on idle tip-in, then something else is preventing the slides from coming up. That could be damaged diaphragm or improperly assembled slide/needle/diaphragm or some other things. It's really easy to make a tiny error in assembly that will screw this up. Or I should say, it's surprisingly difficult to not make an error that would screw it up. If you got carb cleaner on the diaphragms then they are probably DOA.

4. Once you get all this sorted then you may discover other things like compression (valve adjustment, etc.), carb balance, etc. But these carb issues are the most likely and the first to check.

BTW my blog post below will walk you through fixing some of this stuff, even though I wrote it from the perspective of the Mk1 carbs (two-circuit, slightly different). Solutions are the same basically:
https://joshkarnes.blogspot.com/2017/09/fixing-common-gs500-carburetor-issues.html?m=1

[cbw0604]

maybe someone on here can help me.

Probably. Most likely we help you by getting you to investigate until you figure it out for yourself

It takes turning the choke on and turning it over it will start right up but them almost immediately die you have to do this about 15 times and it will slowly run longer and longer until it will run long enough to give it some throttle to keep it running.

So let me clarify:
It starts fine with choke (good!)
it dies when cold even with the choke on (bad)
Eventually with enough persistence you can get it to run more than a few seconds.

Is that about right?

When it starts with choke, what rpm does it idle? Should idle up to ike 3-4K or more rpms with the choke on even when cold. If not, then the choke is not working right. BTW the "choke" really is a jet that gets opened when the choke lever is deployed. Idle mixture/speed etc. won't impact on-choke operation (much).

Another problem thats probably related after it has warmed up enough to sit and idle around 1500rpm if you give it a slight twist on the throttle maybe moving it an inch or so it will sputter a bit and sometime it will die from the sputter.

Most likely the slides are not coming up. Could be a damaged diaphragm or a number of other things. Could be just a big/bad vacuum leak.

Lastly which I believe is also related is once your ride it for about 10 mins and it gets nice and warm

How can you ride it for 10 min if you can't give it any throttle without killing it?

when you pull in the clutch it will idle up to 3000 rpm and sit there until the clutch starts to grab when you start moving again.

This is "hanging idle" caused by your idle speed being set too high (note 1500 above, that's too high). Normally people do this because they adjust the idle mixture and speed before the bike is fully warmed up. In your case I doubt the bike will run well enough long enough to get fully warmed up anyway, but the 10 minute mark is about where it begins to be warmed up. I usually recommend more like 15-20. Then set the idle more like 1100 or 1200. If it still does "hanging idle" then the idle is probably too lean, which means you are setting the idle "speed" higher to compensate. Done right it'll idle at 1100-1200 rpm when it's good and warmed up with the throttle stop basically closed entirely.

Anyway, I'd say it's entirely possible or likely you have more than one thing going on.

1. hanging idle caused by the idle mixture being too lean and the idle speed being set too high in effort to compensate. You may need to +1 the pilot jet, or maybe the pilot fuel orifice in the carb is clogged or that tiny pilot jet (hey, the thing is only 0.175mm!) is clogged. In any case with your problems I'd suggest pulling the carbs and replace the pilot jets. Put in 20s.

2. Vacuum leak is likely, I'd bet the intake boot o-rings are old and hard and don't seal. Might be other places on the Mk2 carbs that have opportunities to make a vacuum leak.

3. If vacuum leak is not causing the hesitation/stalling on idle tip-in, then something else is preventing the slides from coming up. That could be damaged diaphragm or improperly assembled slide/needle/diaphragm or some other things. It's really easy to make a tiny error in assembly that will screw this up. Or I should say, it's surprisingly difficult to not make an error that would screw it up. If you got carb cleaner on the diaphragms then they are probably DOA.

4. Once you get all this sorted then you may discover other things like compression (valve adjustment, etc.), carb balance, etc. But these carb issues are the most likely and the first to check.

BTW my blog post below will walk you through fixing some of this stuff, even though I wrote it from the perspective of the Mk1 carbs (two-circuit, slightly different). Solutions are the same basically:
https://joshkarnes.blogspot.com/2017/09/fixing-common-gs500-carburetor-issues.html?m=1

Ok sorry that was confusing you got it right it starts fine with choke but then dies after a few seconds with the choke still on thats all true with a little persistence after starting it about 10 times with some throttle i can get it to start and stay running and be ridable. I still ride it now just want to get these issues fixed.

In response to the rpm when started with the choke it will only rev up to about 1.5k so like you said probably not working.

In response to the riding it i correct my statement above. After the engine gets hot from riding when you pull up to a red light pull in the clutch bike slowly revs up to 3000 rpm. Light turns green put the bike in first gear and start letting off the clutch rpm drops down and you can ride normal but it repeats every time you stop.

Anyway hope that cleared up the confusion. I will definitely look into the hanging idle and see if after riding for 15 adjusting the idle screw will fix that. Also I will take a look at your blog. What would you say is the best way to find vacuum leaks? Thanks for the help man. Ill update with new info hopefully thursday.

[mr72]

Best way to find vacuum leaks? Just rule them out. Fix everything that might leak as preventative maintenance. "Finding" vacuum leaks is a fool's errand.

$30 worth of hoses and o-rings will absolutely get rid of all possible vacuum leaks as long as the diaphragms and petcock are not damaged. Not worth saving part of that $30 to try and isolate the actual cause of a vacuum leak. Instead rule it out.

Yeah your idle is set too fast. My guess is the "fast warm-up" jet is clogged or the choke is not operating correctly (manually). So basically the bike is very hard to start and run when cold because of malfunctioning choke.

[cbw0604]

Best way to find vacuum leaks? Just rule them out. Fix everything that might leak as preventative maintenance. "Finding" vacuum leaks is a fool's errand.

$30 worth of hoses and o-rings will absolutely get rid of all possible vacuum leaks as long as the diaphragms and petcock are not damaged. Not worth saving part of that $30 to try and isolate the actual cause of a vacuum leak. Instead rule it out.

Yeah your idle is set too fast. My guess is the "fast warm-up" jet is clogged or the choke is not operating correctly (manually). So basically the bike is very hard to start and run when cold because of malfunctioning choke.

I believe i fixed the hanging idle with the fix you provided will make sure tomorrow when i got home from riding today it was late so I just quickly adjusted the idle screw and was able to get the bike to drop from 4000rpm to around 1200 or so and i could rev it and it would drop back down and not "hang"
Ill take a look in the manual to locate all of the vacuum hoses and order some o rings for the carb boots.