Honda GX620 Owner's Manual page 26

SERVICING YOUR ENGINE
Paper air filter element: Tap the filter element several times on a
hard surface to remove dirt, or blow compressed air [not exceeding
30 psi (207 kPa, 2.1 kgf/cm )] through the filter element from the air
cleaner case side.
Never try to brush off dirt; brushing will force dirt into the fibers.
Replace the paper element if it is excessively dirty.
Foam air filter element: Clean in warm soapy water, rinse, and allow
to dry thoroughly. Or clean in nonflammable solvent and allow to
dry. Do not put oil to the foam element.
6. Wipe dirt from the inside of the air cleaner body and cover, using a
moist rag. Be careful to prevent dirt from entering the air chamber
that leads to the carburetor.
7. Place the foam air filter element to the air cleaner cover. Make sure
the seal around the paper air filter element is seated properly. Then
reinstall the paper air filter element and cover to the air cleaner case.
Hook four latch tabs securely.
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