Bad Boy MZ 42 Owner's, Service & Parts Manual page 24

The air cleaner is the engine's only defense against
damaging foreign particles. It is very important that the air
cleaner element is inspected prior to each use. Remove
the element and tap its sides in order to remove debris.
Do not blow the filter out using compressed air. Doing so
will greatly reduce the air cleaner's effectiveness. Replace
yearly; more often in dusty environments. Adhering to these
practices will help prevent loss of power and premature engine
failure.
3.3 Changing the air cleaner
1) Unlock the air cleaner cover and remove to access
the air cleaner.
2) Remove the paper element and precleaner.
3) Replace or wash precleaner in warm water with
detergent. Rinse and allow to air dry.
4) Lightly oil precleaner with new engine
oil; squeeze out excess oil.
5) Replace paper element and place
precleaner onto new paper element.
6) Install onto base and place cover back
on and lock into place.
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