High Altitude Operation - Honda FR650 Owner's Manual

HIGH ALTITUDE OPERATION
At high altitude, the standard air-fuel mixture will be too rich. Performance will
decrease, and fuel consumption will increase. A very rich mixture will also foul
the spark plug and cause hard starting.
High altitude performance can be improved by specific modifications to the
carburetor. If you always operate your tiller at altitudes above 6,OOOfeet (1,800
meters), have your servicing dealer perform this carburetor modification.
Even with carburetor modification, engine horsepower will decrease about
3.5% for each 1,000 foot (300 meter) increase in altitude. The effect of altitude
on horsepower will be greater than this if no carburetor modification is made.
(NOTICE 1
When the carburetor has been modified for high altitude operation, the
air-fuel mixture will be too lean for low altitude use. Operation at altitudes
below 6,OOOfeet (1,800 meters) with a modified carburetor may cause the
engine to overheat and result in serious engine damage. For use at low
altitudes, have your servicing dealer return the carburetor to original
factory specifications.
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