Rato RV160 Manuel Du Propriétaire page 14

PRE-OPERATE...INSPECTION
"Light knocking" or "spark exploding" sound can be hear when the
engine overloading. It is normal. Do not worry about that.
If " knocking" or "spark exploding" sound occur at a steady speed
under normal load, change brand of gasoline; if such phenomena still
happen, consult your dealer for help, otherwise the engine may be
damaged.
When the engine is running, continuously "Knocking" or "spark
exploding" sound occurring will damage engine.
"Knocking" or "spark exploding" sound from misusing will not be
within the valid warranty.
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