DUROMAX XP18HPX, User Manual

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High Altitude Operation
At high altitudes, the standard carburetor air/fuel mixture will be too rich. The 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 engine at altitudes above 3,000 feet (900 meters), have a 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 by 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 3,000 feet (900 meters) with a modified carburetor may cause
the engine to overheat and result in serious engine damage.
Note: Jet kits available for purchase upon request, please contact us at 844-DUROMAX to set up your
parts order.
ENGINE SETUP (CONTINUED)