Based on the picture above, when the throttle valve / gas valve is still closed at stationary speed, the vacuum in the inlet (after the gas valve) so that the high airflow can only flow through the pilot air jet (1) to the pilot outlet (4). Fuel from a float entry through primary space pilot jet and will begin mixing with the air in the pilot jet (4). High vacuum causes the mixture of fuel and air is pulled through the pilot hole / idle (no. 5 picture above). When the engine is on and the throttle has been opened slightly (low speed but still have above rev / speed stationary), then the mixture of fuel and air will flow through the hole no. 4 and no. 5 in the image above. Thus the spin machine will rise as the number of mixture entering the combustion chamber. Equipment which can add to the amount of fuel is the speed channel number two, three and sometimes four. CV-type carburetor footage showing the flow of fuel and air at low speed (see arrow) can be seen in the image below:
