f2 fuel tap leak

[rdleigh55]

hi,my fuel tap lets fuel out in the res and on position without the engine running,i have done a tap overhaul with parts from norbo but still the same,what else could it be?? ,the fuel comes out of carbs overflow pipes quite rapidly,am i right in saying fuel should not leave the tap unless engine is running as it is a vacuum type system.the carbs have been done to spec float heights ect!!!.any help appreciated.cheers leigh

[Shytalk]

I don't think the F2 uses a vacuum system... either way if fuel is coming out of the overflow pipes on the carbs then the float valves aren't sealing, the rubber O ring will be perished.

[rdleigh55]

if its not vacuum type. why is there not a off position on the fuel tap.only prime,reserve and on

[Denzil]

It does use a vaccum system. The small opening is for the pipe that attaches to it and then to the opening on the right hand carb. As said there is no off position because it is under vaccum pressure.

[loop]

I had exactly the same problem after I rebuilt the tap on my F2.
I stripped it down again, in there was still some dirt (old o ring) in the seating.
Wrapped a pencil in a cloth & thoroughly clean it, now works fine.

By rights, fuel shouldn't come out the carb overflows, sound like dirt on the float valve seats as well.
Like Shy says, if you take the seats out the o rings fall apart.

Good luck, let us know how you get on.

[rdleigh55]

thanks for help guys ,have another play with it tomorrow.let you know if i solve it

[rdleigh55]

hi,sorted the tap leak.the plastic part that separates the diaphragm has a very small hole that was blocked.seems to be working how it should and the bikes running great ,even got a quick blast on it