Carburetor Modification for High Altitude Operation
At high altitude,the standard carburetor air-fuel mixturewill be too
rich. Performancewill decrease, and fuel consumption will
increase. A very rich mixture will alsofoul the spark plug and
cause hard starting. High altitudeperformance can be improved by
specific modificationsto the carburetor. If you always operate your
mower at altitudes above 5,000 feet(1,524 meters) have an
authorized Honda servicing dealerperform this carburetor
modification. Even with modification,horsepower will decrease
about 3.5% for each 1,000 ft (300 m) increase in altitude. The
effect of altitude on horsepower will be greater than thisif no
carburetor modification is made.
NOTICE
When the carburetor has been modified for high altitude
operation, the air-fuel mixture will be too lean for lowaltitude use.
Operation at altitudes below 5,000 feet (1,500meters) with a
modified carburetor may cause the engine to overheat and result
in serious engine damage. For use at low altitudes, have an
authorized Honda servicing dealer return the carburetor to original
factory specifications.
Fuel Recommendations
Use unleaded gasoline with a pumpoctane rating of 86 or higher.
This engine is certified to operate on unleadedgasoline. Unleaded
gasoline produces fewer engine and sparkplug deposits and
extends exhaust system life. Neveruse stale or contaminated
gasoline or anoil/gasoline mixture. Avoid getting dirtor water in
the fuel tank.Occasionally you may hear light “sparkknock” or
“pinging” (metallic rappingnoise) while operating under heavy
loads. This is no cause for concern. If sparkknock or pinging
occurs at asteady engine speed, under normal load, change
brands of gasoline.If spark knock or pingingpersists, see an
authorized Honda servicing dealer.
NOTICE
Running the engine with persistent spark knock or pinging can
cause engine damage. Running the engine with persistent spark
knock or pinging is misuse, and theDistributor’s Limited Warranty
(page 51) does not cover parts damaged by misuse.For
oxygenated fuel information refer to page 58.
MAINTENANCE
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