Carburetor (Wg972-E2 - Kubota WG972-E2 Workshop Manual

WG972-E2, DF972-E2, WSM

[2] CARBURETOR (WG972-E2)

Designed for general purpose use, this carburetor provides engines with the ideal fuel-air mixture for all speed
ranges.
1) Float Chamber
When the gasoline in the fuel tank flows into the float chamber (10), the float (9) rises and, when a predetermined
amount of gasoline is in the chamber, it pushes the needle valve (15) against the valve seat (16) to stop additional
gasoline from entering through the inlet port (17). As the gasoline is consumed, the float goes down and more gasoline
is led into the chamber to maintain a constant distance between the main nozzle (6) and the level of the gasoline.
2) Starting System
To start an engine in cold weather, the fuel-air mixture must be richer than normal. A choke valve (18) controlled
by the choke lever (1) is provided to enrich the mixture.
As the choke valve is closed, the air supply is restricted to make the mixture rich. This rich mixture is then supplied
to the intake manifold to facilitate starting.
3) Slow System
When the throttle valve (5) closes, air that flows into the cylinder passes along the valve at a high speed. As a
result, a negative pressure is crated in the pilot outlet (21) which has an outlet port in the inner wall. This causes
gasoline in the main nozzle (6) to flow through the pilot jet (24) to be sucked into the cylinder. Air that enters from the
pilot air jet (25) is mixed with gasoline in the pilot jet (24), atomized in an appropriate condition, sprayed from the pilot
outlet (21) and sucked into the cylinder through the main passage. The slow speed of the engine is controlled by
changing the jet area with the pilot jet (24).
4) Main Carburetor System
The speed of air that flows into the cylinder increases when it passes the venturi (2), and the negative pressure
increase as a result at the tip of the main nozzle (6). The negative pressure causes the gasoline in the float chamber
(10) to flow through the main jet (20) and to be sucked into the main nozzle (6). Air which flows from the main air jet
(4) into the bleeder hole (7) of the main nozzle (6) is mixed with gasoline, atomized in an appropriate condition, then
sprayed from the nozzle tip to the venturi (2) and sucked with the main air into the cylinder.
M-15
GASOLINE / LPG ENGINE
(1) Choke Lever
(2) Venturi
(3) Throttle Shaft
(4) Main Air Jet
(5) Throttle Valve
(6) Main Nozzle
(7) Bleeder Hole
(8) Float Chamber Gasket
(9) Float
(10) Float Chamber
(11) Jet Holder
(12) Solenoid Valve Assembly
(13) Earth Cord
(14) Float Pin
(15) Needle Valve
(16) Valve Seat
(17) Inlet Port
(18) Choke Valve
(19) Carburetor Body
(20) Main Jet
(21) Pilot Outlet
(22) Throttle Stopper Adjusting
Screw
(23) Pilot Screw
(24) Pilot Jet
(25) Pilot Air Jet
W1012968
KiSC issued 01, 2006 A