Honda Car Engine G100 Owner's Manual page 28

Carburetor Modification For High Altitude Operation
At high altitude, the standard carburetor air-fuel mixture will be too rich.
Performance will decrease, and fuel consumption will increase. A very ric
mixture will also foul the spark plug and cause hard starting.
High altitude performance can be improved by specific modifications
to
the
carburetor. If you always operate your engine at altitudes above
1,500
meters (5,000 feet) have an authorized Honda servicing dealer perform
this carburetor modification.
Even with carburetor modification, engine horsepower will decrease about
3.5% for each 300 meter (1,000 foot) increase in altitude. The effect of
altitude on horsepower will be greater than this if no carburetor
modification is made.
I
NOTICE
I
When the carburetor has been modified for high altitude operation, the
air-fuel mixture will be
too
lean for low altitude use. Operation at altitudes
below 1,500 meters (5,000 feet} with a modified carburetor may cause the
engine to overheat and result in serious engine damage. For use at low
altitudes, have an authorized Honda servicing dealer return the carburetor
to original factory specifications.
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