First carb teardown! Overwhelmed...

[jjdcy]

Hello fellow GS500 owners!

New motorcycle rider here (MSF course completed in OCT2013) and new owner of a 2007 Suzuki GS500F! (JAN2014)
Unfortunately, I haven't been able to ride much since I've bought her because not only has the weather been really crappy but because I have a gas leak through the airbox drain tube. I have scoured the internet and found that apparently my float needle is stuck and is causing gas to overflow into my airbox. I have since popped the float bowls off my carbs (had to dremel a slot through one of the screws..will change into allen head bolts soon) and immediately determined that the float bowl gasket needed to be replaced..very brittle..float bowls need to be freed of gunk and I inspected the floats themselves which were fine because they bounced with no resistance. I took off the floats and inspected the needles which both seem to be in perfect condition so it leads me to believe that the float needle valve seat? that seats the needle has to be the suspect. Well one screw came out easily but how do I remove the valve seat itself? Does it just slide out with a tug? Also, I stripped my other carb's screw that holds down it's valve seat..has anyone else had that happen to them? Both valve seats seem to fit very snug and I don't see how the o-ring on it could be a problem. Could I just blow compressed air down it to free any gunk?

Sigh. I've already invested a lot of money into tools while working on this bike and I'm so tempted to bite the bullet and take it to a motorcycle shop.

Any tips welcome.

[Badot]

At least on the older carb models the valve seat is just held in with the pressure from the o-ring (pulls out). Check the fiche on your favorite parts website for your model and it should be apparent.

Also worth noting, you have a vacuum operated petcock that should cut off fuel flow when the bike isn't running. So you have a failure in your needle system, and the petcock vacuum system presumably.

[jjdcy]

Well I guess the newer models have a screw that just slightly overlaps the lip of the needle valve to hold it down in place. I wonder if my dremel can get in there..

It would eventually stop leaking a few days after I've ridden it so I'm assuming it was just leaking gas that was already in the carbs. Is there an easy way to check my petcock vacuum system?

[robfriedenberger]

You have an issue with the floats, and needle. When the bike is off and not running there is not any vacuum. If you were only leaking 2oz of gas than I would think its either a cracked float bowl (never seen one) or lose drain screw....... Seams like your leaking more than 2oz of gas

[jjdcy]

So it's gotta just be the float not sitting right on the seat and probably the float height is off. Yeah, it was definitely more than 2 ounces lol.

Anyone have any experience taking off the valve seats on the newer carbs? Did you just use pliers to pull them out?

How do you measure the float height? Do you just hold the carb body upright and measure from the top of the float to where the float bowl gasket would be?

Sorry for all the questions. I'm just eager to get back on the road! I need to start getting better at riding.

[robfriedenberger]

I wouldn't pull the valve seat unless you see an issue, you can check this with a flash light, I'm sure that the float height is on the wiki some where, i know its in my book but i'm not at home right now. However usually you measure the distance from the carb body (where the gasket sits) to the top of the float. There will be a spec like 22mm or some thing like that That number is very important, off the top of my head i forget what it is for a gs

[radodrill]

An easy way of checking the float height on the bike: set the frame petcock to prime, attach a piece of fuel-grade tubing to the drain nipple, hold the tube in a U-shape beside the float bowls, and slowly open the float drain.  The fuel level in the tube will show you where it is in the carbs; the level should be level with the top of the float bowls.

[BockinBboy]

For GS, I recall float height should be right around 14mm +/- 1mm... I'm almost certain that's the spec for 2 jet carbs, and that 3 jet carbs are slightly higher than that but I don't have my manual right now to verify.

- Bboy

[GI JOE]

I just did float height on my bike. I don't have a manual so I googled gs500 float height and a picture from the book came up. From what I've read and been told, to set the float height, hold the carbs at about a 35° angle. They should just be touching the needle, not resting on it. Then you measure the carb lip to the top of the float (really the bottom of the float but you're holding it upside down for this so it's now the top). Just bend the tab ever so slightly to adjust the level. It will probably take you a few tries to do it right.

[bombsquad83]

I would use the float height tolerance in the manuals as a general guide and a first try.  However, it's much easier to get the verify that the float height is effectively correct with the clear tube from the drain method.   Also, once you've had an issue with a set of float valves, you'll probably have a lot better luck with a new set than trying to adjust with the same float valves that have failed you without having adjusted them in the first place.  They aren't cheap, but it saves a huge headache of leaking gas and adjusting floats over and over and never knowing if you have the right gas level in the bowl.  Might not be a bad idea to change out your fuel lines to rid yourself of any gunk that's built up in them, and since they harden up over time anyway.

[jjdcy]

radodrill: I've read about that method before and I just wouldn't know where to get my hands on a piece of fuel-grade tubing the exact size of the drain nipple.

GI Joe: What exactly did you mean when you said "They should just be touching the needle, not resting on it." And is the tab, the silver tab holding the needle?

bombsquad83: The drain method is so tedious though, I don't want to have to keep rebuilding the bike.

So I cleaned the float bowls that were heavily spotted with gunk and I did my best by cleaning the jets with carb cleaner. I'm going to replace the float bowl gasket and needles as soon as I get my rebuild kits in the mail.

Thanks for the help so far, guys. The GS500 has a great community.

[bombsquad83]

bombsquad83: The drain method is so tedious though, I don't want to have to keep rebuilding the bike.

Fact remains that it's the only way you are going to be able to tell what the gas level is in the bowl with certainty.   From my own experience, I don't trust the needle valves that come in aftermarket rebuild kits to be the same as OEM.  You might have better luck than I did, and you have the newer carbs (I have a '93), but I would want to verify the actual fuel level in the bowls if I were you.

I don't use fuel grade tubing for the job by the way.  That's probably overkill.  It's not like it's permanently mounted to the fuel system.  I just used aquarium air line.  It was cheap and the right size for the carb drain nipple.

[robfriedenberger]

Fuel grade hose can be purchased at any auto parts store, and most lawn an garden stores. If you are state side this includes home depot and lowes. 3/8" usually dose the trick quite nicely

aquarium line can melt from the gas, depending on what it is made of...I would just get fuel line its usually $1-2 a foot

[BockinBboy]

I just use clear vinyl tubing I have hanging in the garage, 25' of it probably cost me 2 bucks when I got it for some other project years ago - gas is only in it for a minute tops, and that gas doesn't go back into the bike... if it were to melt or crack, I'd just cut off another 6 inches from the roll or whatever... but never had an issue like that.  You can find that at any hardware store.

- Bboy