Honda WH15, Owner'S Manual

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53
TECHNICAL INFORMATION
Carburetor Modification for 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 will also foul the spark plug and cause hard starting. Operation at an
altitude that differs from that at which this engine was certified, for extended
periods of time, may increase emissions.
High altitude performance can be improved by specific modifications to the
carburetor. If you always operate your pump at altitudes above 2,000 feet
(610 meters), have your servicing dealer perform this carburetor modification.
This engine, when operated at high altitude with the carburetor modifications
for high altitude use, will meet each emission standard throughout its useful
life.
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.
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 2,000 feet
(610 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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