float valve leak - Can't find the problem

[MOTOMYSZOR]

for the last 3 months I am trying fix my carburetors and it looks like I stuck.....  

It started with small leak from one of tubes from one of the carburetor. Just few drops after ride.
So I decided to buy new float needles and seats made by Tourmax.
I replaced them but during ride I noticed popping from exhaust during deceleration.
I checked vent tubes and 2 of them were moist.

After third time with carburetors on bench, when everything seemed perfect,  I decided to get new float valves from Randy.

Since then I tested all possible combinations: new / old seats with old or new valves.....

The results is always this same:
When i put them upside down and  connect pressure to them and set it to 1 Bar they will hold it for few hours.

From syringe attached to carburetors over night will go around 50ml of petrol until the level will reach half of the length of the clear tube. then it stops.
It looks like this extra petrol goes to all 4 carburetors because after adding more and more petrol finally all of them will start leaking

I have no idea what to do..... or maybe 50ml per night in such cold weather is not that bad.....

[Pat Conlon]

Tank full of fuel, with the bike is shut off, is your fuel pump tight? ........or does it dribble gas?

Where's Noel?

[MOTOMYSZOR]

Fuel pump is OK. Carbs wont be flooded when engine is off.

I have 3 different sets of new float valves and set of new valve seats and old cleaned very well with toothpaste.

And all my bench tests are this same...... petrol from syringe slowly flowing to carburetors......

[Old Rider]

To me it sounds like float height is wrong letting to much fuel into bowls.Float height should be 21.3  - 23.3 mm from gasket mating surface  if i remember right. Measure with the carbs tilted so that
floats barely touch the valve needle spring
Here are some good videos explaining :

https://www.youtube.com/watch?v=Bxx5Iw1xoVw
https://www.youtube.com/watch?v=4iYiCa3Nmqg

If you use a clear tube to measure fuel level it should be like in the picture here:

[MOTOMYSZOR]

Float level is checked..... many times
I have set float level on 23mm. And I measure as it is explained in file section.

I started thinking about buying a new set of valve seats..... just in case

[Old Rider]

If you removed the old carb bowl gaskets and then reused them they often shrink, then they can rub on the float making it sticky.
I made a tread about that here :  http://www.fjowners.com/index.php?topic=18788.0
I recommend using new gaskets. You can make the gaskets original shape again by bowling them for a few minutes in water but best is to buy new.

[Pat Conlon]

Do you have the correct size seats for the FJ fuel pumpers?
(The gravity flow seats are larger and they will leak when subjected to the low pressure of the fuel pump)
http://www.fjowners.com/index.php?topic=9836.0

[ribbert]

Tank full of fuel, with the bike is shut off, is your fuel pump tight? ........or does it dribble gas?

Where's Noel?

Pat, I sent him a PM a week ago with details and photos of the solenoid, float tang divots, fuel pump, float levels etc. and a lot of other info relevant to his problem.

Noel

[Pat Conlon]

Tank full of fuel, with the bike is shut off, is your fuel pump tight? ........or does it dribble gas?

Where's Noel?

Pat, I sent him a PM a week ago with details and photos of the solenoid, float tang divots, fuel pump, float levels etc. and a lot of other info relevant to his problem.

Noel

Cool beans...

[FJ1200W]

for the last 3 months I am trying fix my carburetors and it looks like I stuck.....  

May or may not help, but I used to fill my tank up before I made it home, so next ride, I was ready to go.

I was "overfilling" it, I never would have guessed, but just stopping the fill lower than I had been doing took care of my problem.

Also, there is a valve in the cap, a pressure valve. You might hear it singing from time to time.

I removed that as well.

[racerrad8]

I need to be able to confirm a couple of things.

The fuel is leaking from the bowl vent tubes?
       There are only two of those and they are the larger hoses that go up to the white plastic tees between carbs 1/2 & 3/4.

Or are you seeing fuel in the four smaller cold weather fuel enrichment (choke) hoses?
       There are four of these hoses and the attach to each individual carb.

Popping from the exhaust could indicate a lean condition. If the carbs are popping back through the carbs, the carb bowls will be come pressurized and push fuel out of the four smaller enrichment (choke) hoses.

I see you purchased new float needles only and not the seats. As Pat mentioned, did you get the correct size seats? If you have gravity feed they are marked 2.3. The F/P seats you require are marked 1.5. Secondly, you have to reset the float level from the new to old needles.

The carb bodies where the needle seats insert, how's the surface where the o-ring sits. Is there any corrosion allow fuel to bypass the o-rings into the bowls?

Floats, have you checked to make sure they don't have don't a small wear dimple at the contact point of the needle. That can cause the float to not travel freely and could be a source of fuel leakage.

Sorry, I am not sure if some of this is redundant as Noel has already sent advice via PM and is not visible to the rest of the forum.

Randy - RPM

[MOTOMYSZOR]

I have checked everything today.

Seats are proper size, gasket has enough clearance, fuel level is perfect (23mm)

Petrol is leaking from the smaller hoses. it is not dripping, just a drop of fuel on end of 2 or 3 tubes.
During one of the test rides exhaust turned in to a cannon.... when I stooped petrol was dripping from one of the tubes so I am sure that is from excess of petrol.

For a last month I just conduct bench tests.

Today I checked float valves under microscope.

On left side old one. Right side is the new one. The difference is visible.... maybe that is the problem 

[racerrad8]

What are you seeing in the microscope that you believe is causing the issue?

I'm still not convinced you have a float/needle seat issue. Since fuel is not "running" out that indicates the floats are not bypassing. You stated the fuel pump didn't leak, so you maybe chasing the wrong issue.

If the fuel enrichment dip tubes are not venting, then the could be siphoning fuel from the bowls. The key will be determining what the fuel level on the bowl is doing, rising, falling or maintaining.

Did you install the oversize o-rings around the needle seats and did you "polish" the bore?

Still many questions to determine what your actual problem is.

Randy - RPM

[MOTOMYSZOR]

I think that I found the problem: following Randy's "checklist" I discovered wear dimples on each float.... I filed them down and instant result: over night just 20ml of petrol flown down to carburetors.
So big thanks Randy for Your checklist.

Now the question is: 20ml per night is acceptable or should I buy new floats?

[ribbert]

.....following Randy's "checklist" I discovered wear dimples on each float.... So big thanks Randy for Your checklist.

Did they look like this...



Noel