1986 fj 1200 carbs leaking

[flipmedia]

Hi everyone, I have thoroughly cleaned the carbs and set the float heights to spec but they are still leaking. The float needles look fine and the seats and screens are well cleaned. I also installed new o-rings beneath the seats. This bike is an 86 and has the electronically controlled gravity petcock. I bench tested the carbs with fuel but didn't use the gas tank or petcock for the test. Is the petcock required for testing these carbs as they shutoff fuel when the bike isn't running? I'm assuming the carbs should hold fuel as normal if the needles are closing properly? Could the diaphragm's cause leaking if they aren't sealing correctly? Sorry for the silly questions but I'm at my wits end here.

[PaulG]

Just to clarify a bit more:

Are they leaking from the vent hoses, or from oring connectors at the T's, etc.  How did you clean the carbs? Manually or ultrasound?  Are they leaking on the bench test or after they're installed? If on the bike do they leak immediately or only after the bike is running or on the road?

If you can narrow it down a bit more somebody here should be able to point you in the right direction.

[racerrad8]

In order for fuel to get that high, it is bypassing the needle within the seat or the outside of the brass seat.

You mentioned, you replaced the o-rings "under" the valve seat. I just want to confirm, the o-ring doesn't go under the seat, it goes into the groove on the outside of the seat.

If it is under the seat, you will have a definite fuel bypass.

Nothing else, including the diaphragms will cause the issue.

So, look floats for a heavy saturated one or the needle & seats and float level are the trouble areas.l

Randy - RPM

[flipmedia]

Hi Thank you for your suggestions. I bit the bullet and ordered 4 new float valves, seats, o-rings and screens and the bike is running tops. I did have the o-rings on the outside of the seats as you mentioned and everything appeared to be in good shape. There was no wear on the float valves, even when I blew through the fuel hose into the carbs they were sealing fine. Anyhow replacing them all worked a treat. Thx again

[thich]

i had a similar problem last year. i had removed, cleaned and replaced the rubber bits, but it leaked from one of the vent tubes. i took the advice of a friend and just rode the bike as much as possible. THAT cured it. turns out that sometimes when the carbs are left unused for a long time the floats can get "sticky". they can fetch up and stay in the up position, thus draining your tank on the ground. i found that riding around a bunch and getting those floats moving around was all it took. either way, its a great excuse to go ride. hope this helps someone

[balky1]

i had a similar problem last year. i had removed, cleaned and replaced the rubber bits, but it leaked from one of the vent tubes. i took the advice of a friend and just rode the bike as much as possible. THAT cured it. turns out that sometimes when the carbs are left unused for a long time the floats can get "sticky". they can fetch up and stay in the up position, thus draining your tank on the ground. i found that riding around a bunch and getting those floats moving around was all it took. either way, its a great excuse to go ride. hope this helps someone

Just to clarify - if the float sticks in 'up' position fuel is shut off. No draining possible if the needle and seat O-ring are fine.

[Pat Conlon]

If you've cleaned your carbs correctly, disassembled the floats and scrubbed the pivot pins and the ID of the float bracket, checked the floats for air bubbles, and reassembled correctly, there should be no reason for the floats to stick.
Replacing the float needle seat o rings, that can be a problem, if those new o rings do not go in just so...
...or shit in your fuel tank getting to the float needle seat holding the needle open.