High Altitude Operation - Honda HT3810 Owner's Manual

High altitude operation
At high altitude, the standard carburetor air-fuel mixture will be excessively
rich. Performance will decrease, and fuel consumption will increase.
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 lawn tractor at altitudes higher than 6,000 feet above sea level,
ask your authorized Honda lawn tractor dealer to perform these carburetor
modifications.
Even with suitable carburetor jetting, engine horsepower will decrease ap-
proximately 3.5% for each 1,000 foot increase in altitude. The affect of
altitude on horsepower will be greater than this if no carburetor modification is
made.
CAUTION: Operation of the riding mower at an altitude lower than the car-
buretor is jetted for may result in reduced performance, overheating, and
serious engine damage caused by an excessively lean air/fuel mixture.
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