High Altitude Operation - Honda HRA215 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 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, 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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