Honda EB11000 Owner's Manual page 29

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 hearalight "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 your servicing dealer.
1 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 Distributor's Limited Warranty does not cover parts dama,ged
by misuse.
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