Carburetor Modif ication 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 specif ic modif ications
to the carburetor. If you usually
operate your outboard motor at 3,000
feet (900 meters) or above, consult
with your authorized Honda Marine
Your dealer can determine the
appropriate carburetor settings for the
altitude at which you operate your
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
For complete information, refer to the
battery manufacturer's instructions.
12V-28Ah/5HR (CCA 265)