Carburetor Modification For High Altitude Operation - Honda BF8D Owner's Manual

TECHNICAL INFORMATION
Carburetor Modification for
High Altitude Operation
At altitudes above 3,000 feet
(900 meters), 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.
High altitude operation can be
improved by specific modifications to
the carburetor. If you usually operate
your outboard motor at 3,000 feet
(900 meters) or above, consult with
your authorized Honda Marine dealer.
Your dealer can determine the
appropriate carburetor settings for the
altitude at which you operate your
outboard motor.
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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.
When the carburetor has been
modified for operation at one of the
higher altitude ranges, the air-fuel
mixture will be too lean for operation
at a lower altitude. Operation at
altitudes below the range for which
the carburetor is set may cause the
engine to overheat and result in
serious engine damage. For use at
lower altitudes, have an authorized
Honda Marine dealer modify the
carburetor for the correct altitude
range.