Carburetor Modification For High Altitude Operation - Honda BF5A Owner's Manual

Carburetor Modification for
High Altitude Operation
At altitudes above 2,000 ft (600
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 2,000
ft (600 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.
Settings:
Standard setting is for sea level to
2,000 ft (600 meters).
Mid-altitude setting is for 2,000 ft
(600 meters) to 5,000 ft (1,500
meters).
High-altitude setting is for 5,000 ft
(1,500 meters) and above.
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.
TECHNICAL INFORMATION
When the carburetor has been
modif ied f or operation at one of the
higher altitude ranges, the air-f uel
mixture will be too lean f or
operation at a lower altitude.
Operation at altitudes below the
range f or 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
modif y the carburetor f or the
correct altitude range.
75