Carburetor Adjustment; Carburetor - Honda CR250R 2004 Owner's Manual

5. CARBURETOR ADJUSTMENT

CARBURETOR

The carburetor used on your CR will seldom experience
trouble with the standard settings under average load,
climatic and barometric conditions. However, to fine
tune the engine's power output, the carburetor may re-
quire adjustments for specific racing conditions. To
change the carburetor settings, observe the following
instructions.
Construction:
•
Starting Circuit
A very rich mixture must be delivered to the cylinder
when the engine is being started. When the choke knob
is pulled up, fuel is metered by the starter jet and is
mixed with air from the air passage to provide a rich
mixture for starting. The mixture discharges through
the orifice into the cylinder.
4
2
(1) CHOKE KNOB (2) STARTER JET
(3) AIR PASSAGE (4) ORIFICE
46
•
Slow Circuit
Fuel is metered by the slow jet and is mixed with air that
has been metered by the air screw. The mixture enters
the venturi through the bypass and pilot outlet.
6
(5) SLOW JET
1
(7) BYPASS
3
•
Fuel is metered by the main jet, jet needle and needle
jet. It is then mixed with air coming from the air jet and
enters the venturi past the needle jet.
•
The baffle plate prevents foaming of fuel or abnormal
7
fuel level around the main jet.
•
The float and float valve operate to maintain a constant
level of fuel in the float bowl.
8
5
(6) AIR SCREW
(8) PILOT OUTLET
(9) MAIN JET
(11) NEEDLE JET
(13) BAFFLE PLATE
(15) FLOAT VALVE
Main Circuit
Baffle Plate
Float Bowl
#
&
$
9
(10) JET NEEDLE
(12) AIR JET
(14) FLOAT
%
"
!