Carburetor Modification For Altitude Operation; Fuel Recommendations - Honda HRJ216 Owner's 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.
NOTICE
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 origi-
nal 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 pro-
duces 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.
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 the Warranty does not cover parts damaged by misuse. For
oxygenated fuel information, refer to page 40.
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