Fuel Delivery To Carburetor
Fuel inlet enables the fuel from the tank to enter the carburetor through the fuel filter. From the filter, the fuel flows into the bowl through the float needle valve.
With the fuel bowl empty, the float drops enough to draw the float needle valve completely away from its seat. This allows fuel from the inlet to reach the bowl. As the bowl fills with fuel, the float is pushed higher; this, in turn, presses the needle into its seat, first slowing fuel flow into the bowl, and eventually halting it altogether. As fuel is consumed by the engine, the float lowers and the needle valve re-opens to allow in more fuel via the fuel inlet.
See movie below: