HOLY SHIT! Glad I didn't push the button...

[imdying]

R6_kid, dumb question time... but are you quite sure you know what the needle and seat, and float, are, as opposed to the main needle and jet? Odd question I know, but some of your text is a little odd.

[R6_kid:Me]

The float is the plastic thing filled with air which floats when fuel enters the float bowl, this in turn raises the float needle into the seat - setting the level of fuel in the float bowl.

The main needle is what is lifted up and down by the slide/diaphragm to allow fuel mixture to enter the venturi.

[imdying]

Ok, that's cool... so you can see how fuel gets from the tank, and into the carb, and thus what must be leaking?

Have you setup a carb on the bench with a measured fuel supply, or something similar?

[kwaka_crasher]

I wasn't meaning the float valve needle, I was meaning the Jet Needle.

As someone has already said, this has no effect on fuel getting into the engine when the crank isn't turning i.e. there is no vacuum.

[kwaka_crasher]

So to repeat & clarify what I said before, the only way for fuel to enter the intake and thus the cylinders while not running is through a float valve that is either leaking when closed or not closing. The float bowl overflows out through the lowest jet.

[imdying]

FCRs don't have a bowl overflow outlet? (well duh, sounds like obviously not, but I thought I'd ask)

[george formby]

I'm gonna hit up treads this arvo and price up some new valve seats... they are $13.95USD so hopefully shouldn't be too expensive to get locally. I've used Auckland Carburettor Specialists before - didn't help much at the time, though it wasn't really their fault.

Update: took the fuel pump apart - looks like it's pneumatic, wasn't expecting that. All seals and diaphragms are in good condition.

Keep me posted how you go. At some point I will have to do the same thing.

[george formby]

Google JBX Tech pages, you may be able to download the workshop manual for your TRX.

[jonbuoy]

You can test the seats off the bike - either with fuel in the lines or by blowing gently down the fuel line to each of the carbs - when you lift the float up you'll feel it block off the air. There must be two problems - 1: floats not shutting off the fuel supply and 2: shutoff not working on the fuel supply to the carbs themselves when the engine is off.

[R6_kid:Me]

I'll test the seats after my exam on Tuesday, in the meantime the inline tap seems to be doing it's job.

I have just noticed that there was no hose clip where the fuel supply from the tank goes to the fuel pump, and there wasn't much of a seal between the hose and the fitting (read: it was leaking slowly). Could air leaking in through here release the vacuum on the tap and therefore allow the fuel to flow?

[kwaka_crasher]

I have just noticed that there was no hose clip where the fuel supply from the tank goes to the fuel pump, and there wasn't much of a seal between the hose and the fitting (read: it was leaking slowly). Could air leaking in through here release the vacuum on the tap and therefore allow the fuel to flow?

No. Vacuum OPENS the fuel tap, not closes.

[mud boy]

blah blah blah blah blah blah
i agree

[R6_kid:Me]

Just skimming some of my olds threads. In the end I fitted an inline fuel filter and the issue went away. From memory the internal filter on the fuel tap was toast so I went with the easy fix and just put an $8 fuel filter in the line from the tap to the carbs.