High Altitude Operation - Honda FF 300 Owner's Manual

High altitude operation

At high altitude operation, 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 specific modification to
the carburetor. If you always operate the tiller at altitude higher than
1,500 m (5,000 feet) above sea level, have your authorized Honda
dealer perform these carburetor modifications.
Even with suitable carburetor jetting, engine horsepower will decrease
approximately 3.5 % for each 300 m (1,000 foot) increase in altitude.
The effect of altitude on horsepower will be greater than this if no
carburetor modification is made.
Operation of the tiller at an altitude lower than the carburetor is jetted
for may result in reduced performance, overheating, and serious en-
gine damage caused by an excessively lean air/fuel mixture.
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