High Altitude Adjustment (California Type Only) - Honda 2004 CRF250X Service Manual

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HIGH ALTITUDE ADJUSTMENT
(California type only)
At high altitude, the standard ca r buretor air-fuel
mixture will be too rich. Performance will decrease,
and fuel consumption will i ncrease. A
very
rich mix-
ture will also foul the spark plug and cause hard
starting. Operation at an altitude that differs from
that at which this eng i ne was certified, for extended
periods of time, may increase emissions.
High altitude performa nce can be improved by spe-
cific modifications to the ca rbu retor. If your cus-
tomer always operat es the motorcycle at altitudes
above 6,500 feet (2,000 meters), you should perform
this carburetor modification.
Even with carbu retor modification, engine horse-
power will decrease about 3.5% for each 1,OOO-foot
(300-meter) increase in altitude. The effect of alt i-
tude on horsepower will be greater than this if no
car buretor modification is made.
This engine, when operated at high alti tude with the
carburetor modifications for high altitude use, will
meet each emission standard throughout its useful
life.
Remove the carburetor (page 5- 11).
Remove the float chamber.
Replace the standard main jet with the high altitude
type.
HIGH ALTITUDE MAIN JET:
'04 - '06: " 128
After ' 06: " 130
Check that the O-ring on the float chamber is in
good condition, replace it if necessary.
Install the float chamber.
Remove the jet needle (page 5-13).
Change the jet needle clip to high altitude clip posi-
tion.
HIGH ALTITUDE CLIP POSITION: 1st position from
the top
Install the jet needle (page 5-23).
Install the carburetor (page 5-24).
FUEL SYSTEM
NEEDLE CLI P
JET NEEDLE
5-29