High Altitude Operation - Honda Outboard Motor BF40A/50A Owner's Manual

6. 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 plugs and cause hard starting.
High altitude performance can be improved by specific modifi-
cations to the carburetors. If you always operate your outboard
at altitudes above 5,000 feet (1,500 meters) have an authorized
Honda Marine 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
hiah altitude oueration. the air-fuel mixture will be too lean
foi low altitude use. Oderation at altitudes below 5,000 feet
(1,500 meters) with moditied carburetors may cause the
engine to overheat and result in serious engine damage. For
use at low altitudes, have an authorized Honda Marine
dealer return the carburetors to original factory specifica-
tions.
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