6. OPERATION 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 rich
mixture may also foul the spark plug and cause hard starting.
High altitude performance can be improved by installing a smaller diameter
main fuel jet in the carburetor and readjusting the pilot screw. If you always
operate the mower at altitudes higher than 6,000 feet above sea level, have
an authorized Honda lawn mower dealer perform this carburetor modification.
Even with carburetor modification, engine horsepower will decrease about 3.5%
for each 1,000 foot increase in altitude The effect of altitude on horsepower
will be greater than this if no carburetor modification is made A reduction in
engine horsepower will reduce mowing performance.
When the carburetor is modified for good high altitude operation, the air/fuel
mixture will be too lean at low altitude. Performance will decrease, and the
engine will overheat.
To avoid an excessively lean air/fuel mixture and engine damage, reinstall the
standard main fuel jet and readjust the pilot screw for operation at altitudes
lower than 6,000 feet above sea level.
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