Gs500 problems...won't start

[cmat1120]

So I finally got my gs500 started and idling(idk at what rpm though as I didn't have the tach hooked up), but I have a new problem. After I start it it idles fine for maybe 45 seconds and then just dies. I know that fuel is flowing from the tank(I have tygon lines so I can see it) and the carbs were just cleaned(maybe thats actually where the problem is coming from). It doesn't do anything strange or anything before dying it just idles steadily then dies. If anyone knows what this could be I would appreciate the help.

Thanks!

[Snake2715]

It sounded ok in that video.. was it warmed up before you made that video? Or was that a completely cold start?

You are 1000% positive you have the fuel hoses routed correctly?





That vacuum line goes to the top vent on the left carb.

The "to carbs" hose goes to the BOTTOM T on the carbs.

[cmat1120]

It is routed exactly like that except the vacum hose is going to the right carb(if you are looking forwards while sitting on the bike). Idk if thats an issue, its just the way it was when i got it. I could probably switch it pretty easily. One possibility is I may not have had enough gas in it(I saw fuel flow when turned to prime, but maybe that opens up the reserve as well?). Once I source a filter or buy a whole new tank petcock I'll fill the tank like halfway and try again. But it would run again for about the same amount of time if I started it again(it did take a bit to start again though) so it doesn't seem like that was the problem.

And ya in that video it seemed to be working fine other than probably the wrong idle speed and maybe just a little rough. It had ran for like 30 seconds within the last 5 minutes before that video.

[RossLH]

At least on the earlier carbs, the vacuum port is on the left, the right is plugged. Unless your carbs have been switched, you have no vacuum at the petcock, thus no fuel in the 'ON' position, and a big vacuum leak. If you turned it to PRIME, then back to ON, you could have enough fuel in the float bowls to start the bike and run it for maybe 30 seconds, and the idle would be goofy due to the vacuum leak.

[BockinBboy]

One possibility is I may not have had enough gas in it(I saw fuel flow when turned to prime, but maybe that opens up the reserve as well?).

Prime does draw from the reserve position in the tank.

- Bboy

[cmat1120]

One possibility is I may not have had enough gas in it(I saw fuel flow when turned to prime, but maybe that opens up the reserve as well?).

Prime does draw from the reserve position in the tank.

- Bboy

So even though it doesn't seem to me that it makes a difference I should set up the vacuum ports "correctly" just to eliminate it as an issue. It should be easy enough so ill do that. I just have to figure out how to route a hose into there.( the right side vacuum port is much more accessible)

Is this the right side vacuum port?(where there is a little yellow vacuum cap circled in the pic)

[Kerry]

Is this the right side vacuum port?(where there is a little yellow vacuum cap circled in the pic)

Yes, if by "right" you mean "correct".  (Using standard terminology, that is the left-side vacuum port.  )

[cmat1120]

Ya sorry about that I meant left but said right , so that's the side that I should attach the vacuum hose from the petcock to?

Also it seems to be running very rich. Plugs are black and it seems to almost run better with the air filter taken out(which was pretty dirty). Is there a way to adjust the mixture without taking the carbs out?

Also here is a video of it. I don't really know what I'm doing in it to be honest, but maybe some of you more experienced guys can notice something in it. Please ask me questions or give me suggestions.

[RossLH]

It looks like the bike starts right up when you turn it to prime, then dies shortly after you turn it back to on. That "vacuum port" on the right side carb isn't a vacuum port. It's not drilled through, there's no hole there. If you pull the vacuum hose off, you can see that it is plugged, it goes nowhere.

If you keep the bike on prime, does it keep running?

Running rich can possibly be attributed to floats being a little too high. Check the heights with a clear tube, make sure the gas stays level with the float bowl gasket, and not a millimeter higher.

[Snake2715]

Heres my suggestion. Plug the right (literally) carb nipple. They sell plugs at the auto store its $3 for a mix lot. Get the tightest one you can out of the package over the nipple and use that.

Then hook the hose up to the left carb as its supposed to be. That will allow the vacuum to pull the fuel.

Something else is you can actually feel a pulse through the gas lines while its running if you put your finger on the lines while the petcock is switched to that line. The other line wont ahve this pulse, move the petcock to reserve and now the reserve line will have the pulse.

My understanding is that pulse is the vacuum.


its likely the right carb is not giving you any vacuum and now the left carb nipple is causing a vacuum leak.

Let us know.

[cmat1120]

I did switch them and the results are basically the same. The vacuum hose is on the left and the cap is on the right. Maybe there is something else wrong with the vacuum? It definitely seems like the vacuum not pulling fuel is my problem. Other than running too rich which I believe is a separate issue.

Also when I pull the vacuum hose off of the carb it's a little wet with I'm guessing fuel...is that normal?

[Kerry]

It sounds like this thread may be a follow-up to another.  My apologies if I repeat anything....

A dirty air filter and black plugs certainly do go together.  See the [Haynes Spark Plug Chart].

Have you already checked the carburetor float heights? (See my [Float Height Check on a Suzuki GS500E] page.)  Even though fuel is flowing from the tank, it may not be flowing at an acceptable rate.  You were able to start the bike multiple times in the video, so I'm guessing that the fuel flow rate could be too low, but probably not too high.  With a long enough "float height check hose" you might even be able to monitor the float height while the bike is running.

I couldn't tell for sure which fuel selector switch positions you were switching between in the video.  ON?  RES?  PRI?  I would suggest leaving it on PRI until the bike runs well, and THEN tackling any vacuum issues related to the ON and RES positions.

[cmat1120]

The spark plug isn't nearly as black as that carbon fouling picture, but it is a little blacker than normal. I'm going to go try that float check right now... Ill edit this with the results when I get back.

So my drain doesn't extend at all... its pretty much flush... I don't have a way of attaching any hose

[RossLH]

Also when I pull the vacuum hose off of the carb it's a little wet with I'm guessing fuel...is that normal?

Well that's a problem in and of itself. Fuel in the vacuum line could very well be a sign of a torn petcock diaphragm, and if such will cause the bike to run rich when in prime. That actually happened to me, the vacuum line was pulling fuel through the diaphragm. Definitely a mess.

[cmat1120]

It looks like the bike starts right up when you turn it to prime, then dies shortly after you turn it back to on. That "vacuum port" on the right side carb isn't a vacuum port. It's not drilled through, there's no hole there. If you pull the vacuum hose off, you can see that it is plugged, it goes nowhere.

If you keep the bike on prime, does it keep running?

Running rich can possibly be attributed to floats being a little too high. Check the heights with a clear tube, make sure the gas stays level with the float bowl gasket, and not a millimeter higher.

Sorry I didn't see your reply till now. So that's not a vacuum port meaning my hose is in the wrong place? or there just is no "port"? And I haven't really checked yet to see if it will just keep running on prime, I could try though. And I wish I could check the float height, but like I said there's nothing to attach a hose to on my carbs for some reason.

Ill go try running it on prime now.

So now it just won't start. I tried putting the choke on and putting it on prime and nothing's working. I'm using my car's battery so I'm able to crank it quite a bit, but still nothing.

Also is it normal to be able to start the bike with the kickstand down and the clutch lever out?(The bike is in neutral of course)


Is it possible my floats are set incorrectly and are flooding the engine or something?(Basically is it worth taking out the airbox and carbs to check?) Now I just want to get the bike started so I can test if it runs on prime. I'm thinking im going to just get a new petcock or switch to a manual one anyways if that works.

Here's a video of where I'm stuck right now:

Things I've tested:
Fuel is flowing at least into the float bowls(at least when I set it to prime)
I've moved the idle screw all over the place to no avail
My sparkplugs are sparking fine
My car's battery(what mi using for the bike to test) is fully charged
Air is being sucked through the airbox(filter is off cause its so dirty and I appear to be running rich anyways)

So I seem to have fuel, air and spark... so I can't figure out what I'm missing. Only thing that makes sense to me is maybe too much fuel, but I don't know how to fix that.

Also I do feel a pulse on the fuel line when its cranking if that means anything...

[RossLH]

Sorry I didn't see your reply till now. So that's not a vacuum port meaning my hose is in the wrong place? or there just is no "port"? And I haven't really checked yet to see if it will just keep running on prime, I could try though. And I wish I could check the float height, but like I said there's nothing to attach a hose to on my carbs for some reason.

I'm saying normally there is no port there. At a glance, the carbs look the same, but only the left vacuum port is drilled through from the factory. There is no hole in the right carb.

On top of that, it sounds like you might have a bad petcock, judging by the fuel in the vacuum line. At this point, here's what I'd do: first, check the float heights with a clear tube while the carbs are still on the bike. If those check out, good. If not, pull the carbs, clean them out real good, and adjust the floats as needed. Check the vacuum ports on each carb, make sure you don't for some reason have both of them drilled out. Remove the petcock and check for tears--I'd just suck on the vacuum hose and see if you can pull any air through. It doesn't take much vacuum at all to operate the diaphragm, you can easily do that with your lungs. If air continues to come through, the diaphragm is torn.

So....summary:

1. Check floats. If they're good, skip to step 3.
2. Remove carbs, clean carbs, adjust floats.
3. Check vacuum ports on either carb, make sure nothing is out of the ordinary. The left carb should be drilled through, the right carb should not.
4. Remove petcock and check for tears.

Stop trying to crank your bike. That's not helping.

[cmat1120]

Thank you for the help! Just one question: how might I check floats without having that drainage nipple on the bottom of my carbs?(It's just flat with a hole) Should I just measure the distance like it says herehttp://cgi.stanford.edu/~sanjayd/gs500/Maintenance/FloatHeight? I don't have calipers, but I might have a ruler with mm on it.

Also I apologize for any ignorance I might display lol. This is the first bike I've ever had or worked on so I am very new to just about everything here.

And you were completely right. I took apart my petcock(just 4 screws) and the diaphragm was very torn.

[Kerry]

Should I just measure the distance like it says here http://cgi.stanford.edu/~sanjayd/gs500/Maintenance/FloatHeight? I don't have calipers, but I might have a ruler with mm on it.

That's how I have always done it.  In fact, I just did it the other day to help out a GS rider who brought his carbs down from Salt Lake City.  In the inverted position, his floats had no "float" at all.  By repeatedly bending the metal tab/tang and measuring from the side with a ruler (right at the point where the tang touched the tiny "plunger" on the end of the needle and stopped swinging) we got them up to about 14.2 mm each.  We "bench tested" the float heights with a clear tube, but I guess you'll have to skip that step.  He took the carbs home, installed them, and was able to start and ride his bike.

Good Luck with the procedure!

Also I apologize for any ignorance I might display lol. This is the first bike I've ever had or worked on so I am very new to just about everything here.

No worries.  All of us have either "been there" or we're going to be.  Keep on keepin' on! 

[Snake2715]

Also I apologize for any ignorance I might display lol. This is the first bike I've ever had or worked on so I am very new to just about everything here.

And you were completely right. I took apart my petcock(just 4 screws) and the diaphragm was very torn.

Yeah man I havent been here long but I have seen enough new users come along start to tear things apart and just disappear..  my guess is its  bungled mess and or they gave up or sold the bike.

Your making good progress, and it sounds like you want it correct.. which in my book is the way to do it. Some I know say if it runs just ride it, but I prefer to have it run correctly.

So both bowls have the drain knocked off them? Odd.

[cmat1120]

So I just checked one and if I did it correctly it was 1.27 mm(.05 inches since im using inches her because I have no calipers) low. I bent the tab so that it was exactly .55 inches(which is about 14mm) since aren't the earlier gs's supposed to be less than 14.6? Never mind about that i re-read the information. So I'm within about half a mm of the recommended settings which should be close enough I think.

Heres a picture of where I'm measuring it looked like thats what the picture was referencing, but I could be very wrong... feel free to tell me why it's wrong and how to do it correctly 



My mixture screws were also only like 1.5-2 turns out so I turned them out to 2.5. Should this adjustment make the bike leaner or richer?


Also if I put a vacuum cap on the petcock and the carbs, can I still run the bike with the PRI setting? and then turn it to ON when I stop running/riding it?