Honda GX610 Owner's Manual page 28

SERVICING YOUR HONDA ENGINE
FUEL RECOMMENDATIONS
Use unleaded gasoline with a pump octane rating of 86 or higher.
These engines are 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 oiI/gasoline mixture.
Avoid getting dirt or water in the fuel tank.
Occasionally you may hear a 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.
m
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 Warrantydoes not cover parts damaged
by misuse.
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