Leaking Carb

[545863]

I dismantled and ultrasonically cleaned the carb on my CB100N. I re-assembled it, (correctly as I thought), turned the fuel tap on and petrol leaked out via the drain tube. I tried a new float valve but fuel leaked straight out again. While re-assembling the carb I blew down the fuel tube, lifted the float and it cut off the air flow at the correct position so assumed that all was correct. Float height was set at 12.5mm. Any suggestions what to try next welcomed. Thanks.

[Bryanj]

The overflow pipe in the float bowl may be crackef

[545863]

The overflow pipe looks O.K.

I should have added that I tested the float in a bowl of water and it has no leaks.

[taysidedragon]

The overflow pipe in the float bowl may be crackef

That happened to one of mine. The fuel was leaking out between the overflow pipe and float bowl.
I got another float bowl to replace the leaky one.

[545863]

The petrol is coming out from the drain tube, I put the tube in a bottle to collect it, it is not coming from anywhere else.

[Bryanj]

Thats exactly what happens if the tube in the floatbowl is cracked

[545863]

Sorry to harp on about this, as I final test I filled the float bowl up with petrol while it was off the carb, nothing leaked out, surely if the tube in the float bowl was cracked or damaged fuel would have leaked past it, or am I just being thick here?

[Bryanj]

In that case fuel is leaking past the float valve

[545863]

I fitted a new float valve so assume that the seat might be worn? Are they replaceable?