High Altitude Operation - Honda HS521 Owner's Manual

HIGH ALTITUDE OPERATION
At high altitude, the standard carburetor air-fuel mixture will be excessive-
ly 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 snowthrower at altitudes higher than 6,000 feet above
sea level, have your authorized Honda Snowthrower dealer 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 effect of
altitude on horsepower will be greater than this if no carburetor modifica-
tion is made.
m
Operation of the snowthrower 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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