High Altitude Operation - Honda Marine BF40A 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.
-1 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 below 5,000
feet (1,500
meters) with modified 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 specifications.
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