hello i have a piaggio zip 50 ac its been a project bike and is held back from its m.o.t because of a leaking carb. iv tested the suction pipe thats fine fitted a new tap on the petrol tank and tried another float valve form my other bike and its still leaking. the petrol is coming up from the float chamber and is running out the back of the carb into the air box saturating the sponge filter in the air box with petrol. the only other thing i can think of an im nit picking here, is the size of the main jet its a 72. my local bike mechanic has told me that a normal main jet size for a 50cc is around 65. if you can help please do, cheers.
im suffering same issue on nrg leakiing all around carb (but looks like leaking from float bowl gasket (gasket perished maybe) but isnt the needle supposed to shut it off anyway? so im guessing i got crud in it still even though ive cleaned the needle and valve seat 100 times errrrrrrrrrrrrrrr
i have replaced the float valve it is leaking up from the float chamber through the main jet as soon as i cut the engine out it builds up with fuel around air intake straight away .
On the white plastic float there is a tiny metal part that pushes on the needle valve, carefully bend it up to shut petrol off at a lower level.
50cc only have plastic floats which you cant adjust (i think) well mines not leaking anymore theirs only a few things for a leaky carb 1. check bowl gasket is ok 2. check float needle looks ok 3. check float needle seat looks ok/clean (what the float needle pushes up into) 4. some carbs like mikuni etc have a removable float needle seat which has a oring in it heres a way to check your carb take float bowl off your carb then take vacume pipe of your carb now get your hand on the float bowl and suck on vacum petrol will pour out the valve seat push up float bowl slowly (but keep sucking) then see if the petrol shuts off when float bowl is pushed up level even better take carb off bike and just pour petrol on it and push up float bow
