nx650 fuel leakage

[rob46]

Hi folks.

My dommie has been leaking petrol (via the overflow pipe) on and off for about 6 months. It usually just meant i had to turn the tap off everytime i parked up. In this time i've had the carb off about 5 times. I'm assuming the float valve is not working correctly. However it looks fine, and when i put it all together the problem disappears for months or weeks.

It suddenly came back today, but this time it continues to leak even when the engine is running.

Is a new float-valve going to sort this problem or could it be something else. The thing that confuses me is why the problem comes and goes. Surely if the float valve was gone - it would leak all the time.

Thanks for any tips.
Rob