High Altitude Operation - Honda Marine BF25A Owner's Manual

7. OPERATION
High Altitude Operation
At high altitude, the standard carburetor air-fuel mixture
will be too rich. Performance will decrease, and fuel con-
sumption will increase. A very rich mixture will also foul
the spark plug and cause hard starting.
High altitude performance can be improved by specific
modifications to the carburetors. If you always operate
your outboard at altitudes above 6,000 feet (1,800 meters)
have an authorized Honda Marine or Outboard Motor
dealer perform this carburetor modification.
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.
NOTICE When the carburetors have been modified
for high altitude operation, the air-fuel mixture will be
too lean for low altitude use. Operation at altitudes be-
low 6,000 feet (1,800 meters) with modified carbure-
tors may cause the engine to overheat and result in
serious engine damage. For use at low altitudes, have
an authorized Honda Marine or Outboard Motor
dealer return the carburetors to original factory speci-
fications.
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