8. Operation of Carburetor
1) Pilot system
Pilot system adjusts flow in range of 0 to1/4 opening of Throttle Valve (Th.V.). Fuel will enter from Main Jet (MJ), and subsequently measure by Pilot Jet (PJ). On the other hand, air weighed at the Pilot Air Jet (PAJ) is mixed with fuel, and sprayed from Pilot Outlet or Bypass (BP), and will further make mix condition better by main air and supplied to engine.
Under idling condition, air will be sucked in from Bypass (BP) also, and mixed air will be sprayed from Pilot Outlet (PO), but when Throttle Valve (Th.V.) is opened slightly, negative pressure applied on pilot system becomes large, and mixed air is also sprayed from Bypass (BP).
In addition, in opening range of 1/8 to 1/4, fuel of main system will be added along with pilot system. When Throttle Valve (Th.V.) is opened, air volume is increased, and pressure drop increase. As a result, fuel will be sucked up from Main Jet (MJ) and sprayed by Main Nozzle (MN). At this opening, mixed air will be sprayed at 3 pints: Main Nozzle (MN), Pilot Outlet (PO), and Bypass (BP), and then supplied to engine.
2) Main System
Main system will work at over 1/4 opening where pilot system is almost disabled.
When Throttle Valve (Th.V.) opens, air volume will increase. Since airflow resistance is increased at venture tube, pressure drop at the tip of Main Nozzle (MN) increases. Thus, sucked fuel is increased. Here, fuel is measured at Main Jet (MJ), and sprayed by Main Nozzle (MN).
A bleed port is provided at Main Nozzle to suck high-pressure air at venture tube through Main Air Jet (MAJ). Then, fuel inside Main Nozzle will be thinned through use of this bleed port to compensate tendency of thickening as high speed is increased. As a result, mixed gas with proper mixing ratio can always be sprayed.