Carburetor Modification For Altitude Operation; Fuel Recommendations - Honda HRJ216K2 Manual

Carburetor Modification for 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 lawn mower at altitude
above 1,500 meters, have your servicing dealer perform this
carburetor modifications.
Even with carburetor modification, engine horsepower will decrease
about 3.5% for each 300 meters 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
altitude below 1,500 meters with a modified carburetor may cause the
engine to overheat and result in serious engine damage. For use at
low altitude, have your servicing dealer return the carburetor to
original factory specifications.

Fuel Recommendations

Use unleaded gasoline with a pump octane rating of 86 or higher. This
engine is certified to operate on unleaded gasoline. Unleaded gasoline
produces fewer engine and spark plug deposits and extends exhaust
system life. Never use stale or contaminated gasoline or an oil/
gasoline mixture. Avoid getting dirt or water in the fuel tank.
Occasionally you may hear light ''spark knock'' or ''pinging'' (metallic
rapping noise) while operating under heavy loads. This is no cause for
concern. If spark knock or pinging occurs at a steady engine speed,
under normal load, change brands of gasoline. If spark knock or
pinging persists, see an authorized Honda servicing dealer.
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 the Warranty does not cover parts
damaged by misuse. For oxygenated fuel information, refer to page
43 .
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