Both carbs leak Fuel - Floats dont float - Vapour lock!

[galahs]

I have had a very similar problem to the member in this post http://gstwins.com/gsboard/index.php?topic=11149.0

I was riding my bike for about an hour on a hot day. All was going well until I was stopped at a red light for a very long period.

Whilst waiting there I noticed my idle was slowing to the point where the bike was about to stop. I gave a quick rev of the bike and she sprung back into life but then proceeded to drop revs to the point that she would stall.

The only way I could keep the bike going was to keep its revs at 3000rpm or above.

When I stopped the bike I noticed fuel dripping out of my air filter.


I wont bore you with all the details of my dangerous ride home, but it was scary with the bike well down on power and surging and spluttering quite dangerously. Still if I let the bike idle she wanted to stall. If she stalled the procedure to start her was similar to what you have to do tto start a flooded engine. Wide open throttle when you cranked her.



Now after a quick read on here I decided to check my float heights.


Sheet! They are non existent on both sides!!!

The fuel will keep flowing right on out of the carbs.

So I pulled the float bowls off and checked the float needles. They were both shmick! Not grit and still has a perfect cone point.
 
I bent the float tab so it would close the valve earlier then tried pouring fuel down the fuel line again. Still it comes out of both sides carbs!!!

I repulled the bowls, and tested the float needle by ever so very very lightly pushing it into its recess and then adding fuel to the fuel lines. It seals perfectly!!!


  Now I'm really at a loss.  Why would both carbs develop this problem simultaneously and why hasn't adjusting the float tab made any difference what so ever?

Help!

[galahs]

Basically this is where I think I have a fuel problem



When I pour fuel into the fuel hose, after filling the float bowls it then runs out of these little holes at the bottom of the carburettor air intake.








This is what I have done so far to try and fix the problem



Bent the float tab up and tightened the screw that holds the float valve seat.
Also cleaned all the jets and the float bowl (though they all looked brand new and no blockages to be seen)







The float needle still looks brand new!










Here's a pic of the carbs with the float removed.




Could the float valve seat be the problem?
Can it be easily removed?
Is there an O-ring there that could be stuffed?






Any suggestions or advice would be hugely appreciated.


The fact both carbs seem to have the same problem is what is really perplexing me. What are the odds they both got the same problem simultaneously???


Is there something else I am over looking?

[The Buddha]

You may have a seat O ring issue ... the 01 and later carbs are very hard to bend the float tangs on. I'd just leave them be and figure out by blowing with your mouth into the gas line and seeing where its comming from.
Cool.
Srinath.

[galahs]

So can the float seat just be pulled out after removing the single screw?

Is it held in place by an O-ring?

because atm I can't see an O-ring anywhere 

[Jughead]

Is your Floats full of Gas? if they develop a leak and Fill with gas they won't float enough to Close the Needle.I may just be the way the Picture looks but the Lower Side of those Floats look a Little Darker than the Back Sides.

[scratch]

Yep, his floats look like they have fluid in them; there must be a hole or crack along the seam that lets gas in and they wont float and close the needle and seat.

Galahs - can you verify this?

[galahs]

They didn't feel like there was fuel in them, but I will rule that out as a possibility today. 

[Jughead]

Take them Out and Shake them if you feel and Hear Gas Sloshing Around toss them and Buy new Floats.I've Always had a bad Feeling about Plastic Floats and Vibration after they Turn Dark and Harden.With Brass Floats they were easily Fixable.With Plastic ones you may be able to fix them Temorarily with Epoxy but I wouldn't trust them too far.

[galahs]

Unfortunately I've removed the floats and they are empty. I submerged them in fuel and they don't seem to be any air bubbles coming from it to indicate a leak.

personally I think the floats are a crap design! Rotate them on their pivot point and you notice the movement the tab places on the float needle is minimal.


I also tried turning the carbs upside down and blowing down the fuel line. Seems to be a perfect seal. Si its obvious the floats are not pushing enough pressure up on the float needle. Why I wonder?

Could the floats have gotten heavier with age? (They're only just over a year old!!!)

[galahs]

another thought....  could it be possible that the fuel I am using is less dense therefor why both carbs floats to not seem to be raising high enough to seal 

I filled up the day before the problems happened. Rode 20km home mostly doing highway speeds.

Then the next day rode for 45 minutes on the motoway (6000 rpm might have hidden the problem) Then it showed its head when I got into town in the stop start driving.)

Considering both carbs are leaking and both carbs are basically independent but share the same fuel supply... could I be on something?

I'm going to try some different furl right now.

[Jughead]

Hmmmm thats Funny it's Possible that you may have got a BIG slug of Ethanol that had settled out of the Gas at the Station but I would say the Floats would Float just as much in alcohol as they would in Gas.You could Experiment with Rubbing alcohol and then gas to see if there is a Difference.I wouldn't think that the would be since Alcohol is Burned straight in some race Bikes,Quads ETC. and I've never Heard of Floats Sinking.

[galahs]

Ahhhhhhhhhh! 


different fuel and it still flows out of the carbs like a tap!

Both sides just wont seal!!! 

[galahs]

From the link I posted in the first thread...

Diagnosis : not sure.. but the mech tightened the carb values ? - if you look at this diagram :

<<<old link>>>

it's screw #13.  He said that they were tightened to spec before, but tightened them a bit more (still in spec).   He gave me a couple of pointers where to look if it happens again.

I can only see one screw in the carb but I don't know how that could make a difference.

[galahs]

Now if I manually push the float up ever so gently, it is at this position (it can go much higher) that the float needle seals perfectly.
ie. I can't blow through the fuel line.




So if the float does indeed float it should seal.

So maybe my float doesn't float enough anymore but it doesn't have any fuel in it and I have submerged it in fuel looking for leaks and found none.



Arghhhhhh!!


And I just looked it up to find a single replacement float costs $20 US. What a rip off! (and a fair chunk of cash  for something that may not be the problem)

[sledge]

Have you had a careful look around the area where the float pivots and is it free on the pin? Look for cracks or distortion in the plastic and the metal carb` body. Could something be physicaly limiting the floats travel and preventing it from moving the valve into position? It might be free to move by hand but will probably act differently when fuel is in the bowl.

[galahs]

Yeah it all looks good but tomorrow I'll have another look. Again I find it strange that both floats seemed to go at the same time.

Wonder if the heat of the hot day, plus idling for a long period did something?

[Wrecent_Wryder]

[45

[sledge]

Thinking about it I had a similar thing happen on the GS a few years ago, it was a particularly hot day and I had just tanked up. I left the bike idling on the drive for a few mins for whatever reason when I got home and found it had dumped some fuel when I returned to it, it ran rough for a few secs but cleared itself. It never did it again so I forgot about it until now

We know fuel expands when hot and you are in an area with a high ambient temperature, maybe fuel somewhere in the circuit is becoming pressurised due to the effects of the heat and resultant expansion and it is just "blowing out" the overflow. Perhaps a lot of sun on the tank is enough to cause it. I would have a close look at the filler-cap and check the vents are not blocked, also under the tank at all the pipework making sure nothing is blocked or kinked.

[galahs]

I had the thought that it might have been caused by vapour lock or something when it first happened but now that I have disassembled the bike the fuel I'm pouring in is not hot, the engine isn't even running and the carbs still overflow just by pouring fuel into the fuel line.

I have also checked both float heights using the clear tube method and the float level is high... as high as the overflow pipe in the carb mouth.



The floats seem to rotate easily/freely/smoothly on their shaft so I can't see that hindering their movement. And the float needle valve seals correctly it I gently raise the floats (float bowl off)

Just once I put the float bowl bak on and pour fuel into the fuel hose it continues to fill up the float bowl until it starts flowing out the over flow.

So for some reason my floats (I'm having the same problem on both carbs)  is not pushing the needle valve high enough to seal the inlet and preventing the bowls from flooding.

[scratch]

I've had a similar thing that happened to sledge, happen 20 years ago on a black bike that I once owned - filled up on a hot day, and as soon as I hung up the pump nozzle, I turned around and the gas was overflowing out the filler neck all over the tank!

Galahs - two tings:

1. With the floats installed, but without the floatbowls, turn the carbs sideways with the floats away from you, hold them about waist high so you can look across both carbs, lining up the floatbowl surfaces.  Slowly rotate the carbs toward you (maintaining the alignment with your eyes (like you're shooting)), and observe when the float closest to you stops moving, apying special attention to where the needle stops, too.  This is where it actually stops when fuel is in there.

Now you stated the the fuel level is as high as the overflow pipe in the carb mouth, that's your problem.

2. Pull the floats and put them in a bowl of gas for about a fifteen minutes to half an hour.  If they sink, or take in gas, you'll know that's the problem.