Kohler COURAGE SV710-740 - Section 5. Fuel System and Governor

5.4
Section 5
Fuel System and Governor
Slow Circuit: (See Figure 5-2) At low speeds the engine operates only on the slow circuit. As a metered amount
of air is drawn through the slow air bleed jet, fuel is drawn through the main jet and further metered through
the slow jet. Air and fuel are mixed in the body of the slow jet and exit to the transfer port. From the transfer
port this air fuel mixture is delivered to the idle progression chamber. From the idle progression chamber the air
fuel mixture is metered through the idle port passage. At low idle when the vacuum signal is weak, the air fuel
mixture is controlled by the preset idle mixture seing. This mixture is then mixed with the main body of air and
delivered to the engine. As the throle plate opening increases, greater amounts of air fuel mixture are drawn
in through the xed and metered idle progression holes. As the throle plate opens further the vacuum signal
becomes great enough so the main circuit begins to work.
Figure 5-2. Slow Circuit (Typical).
Fuel Inlet
Float Valve
Seat
Float Valve
Main Jet
Float
Main
Emulsion
Hole
Idle Speed
(RPM)
Adjustment
Screw
Air
Fuel
Mixture
Fuel Shut-Off Solenoid
with Main Jet
Main Jet
Slow Passage Pipe
Main Nozzle
Throttle Valve
Idle Progression Holes
Idle Limiter Jet
Low (Idle) Mixture Screw
Idle Port
Idle
Progression
Chamber
Slow Jet
Slow Air Bleed Jet
Choke Valve
Main Air Bleed Jet
Bowl Vent
Spring
Transfer
Port
Nikki Carburetors Only
Idle Port
Idle Limiter
Jet
Capped/Preset
Low (Idle)
Mixture Setting