136
High Altitude Carburetor Adjustment
Technical Information
When the carburetor has been modif ied f or
high altitude operation, the air-f uel mixture
will be too lean f or low altitude use. Operation
at altitudes below 5,000 f eet (1,500 meters)
with a modif ied carburetor may cause the
engine to overheat and result in serious engine
damage. For use at low altitudes, have your
servicing dealer return the carburetor to
original f actory specif ications.
At high altitude, the standard carburetor air-
fuel mixture will be too rich. Performance will
decrease, and fuel consumption will increase. A
very rich mixture will also foul the spark plug
and cause hard starting. Operation at an altitude
that differs from that at which this engine was
certified, for extended periods of time, may
increase emissions.
Even with carburetor modification, engine
horsepower will decrease about 3.5% for each
1,000-foot (300-meter) increase in altitude. The
effect of altitude on horsepower will be greater
than this if no carburetor modification is made.
High altitude performance can be improved by
specific modifications to the carburetor. If you
always operate your engine at altitudes above
6,500 feet (2,000 meters), have your servicing
dealer perform this carburetor modification.
This engine, when operated at high altitude
with the carburetor modifications for high
altitude use, will meet each emission standard
throughout its useful life.
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Содержание CRF70F 2009
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