Fuel System - Honda G100K2 Applications Manual

FUEL SYSTEM

CARBURETTOR OPERATION
Choke operation
With the choke valve closed and throttle valve open, vacuum in the carburetor venturi is high.
Fuel is drawn up through the pilot jet and mixed with air from the pilot air jet; this fuel/air mixture passes through the
idle port and bypass port. Further enrichment of this mixture is done by fuel supplied through the main nozzle.
Slow circuit (low rpm and idling)
With the throttle valve opened slightly (idle position), a vacuum is produced in the bypass and idle port.
Fuel is drawn up through the pilot jet and mixed with air from the pilot air jet; this fuel/air mixture passes through the
idle port and bypass port. As this mixture discharges into the venturi, it mixes with air moving through the carburetor
body, thereby producing the final mixture for slow speed operation. As the throttle valve is opened further, it frees
more bypass openings and more air/fuel mixture is provided to the engine.
Main circuit (high rpm)
When the throttle valve is opened, enough air is moving through the carburetor venturi to produce a high vacuum.
Since the main nozzle is centered in the venturi, the atmospheric pressure in the float chamber pushes fuel through
the main jet into the main nozzle. Fuel moving up through the main jet is mixed with air from the air jet in the
emulsion tube. As this mixture flows out through the main nozzle, it is mixed with air flowing through the venturi to
produce the final mixture.
RELATION OF CARBURETTOR SETTINGS TO ENGINE PERFORMANCE
Main
jet
Fuel
level
Pilot
jet
Bypass
holes
Pilot screw
adjustment
Choke
valve
Governor
adjustment
Air vent
holes
Throttle valve
Bypass
Idle port
Pilot jet
Pilot screw
Emulsion tube
Wide open Partial
throttle- loaded high speed
loaded
O O
O O
O
O
O
O
Main nozzle
Main jet Float
No load- Start-ability Low
temperature
start
O O
O O
O
O
O
O
O
- 10 -
Choke valve
AIR FLOW
Pilot air jet
Air jet
Fuel entry
Float needle valve
Float chamber
Inclined Idle stability
usage
O O
O
O
O O
O
O O
O
Hot restart
O
O
O
O