See also:

When checking or servicing in the engine compartment while the engine is running
A running engine can be dangerous. Keep your fingers, hands, clothing, hair and tools away from the cooling fan, belts and any other moving engine parts. Removing rings, watches and ties is advis ...

Air cleaner element
Do not operate the engine with the air cleaner element removed. The air cleaner element not only filters intake air but also stops flames if the engine backfires. If the air cleaner elem ...

Fuel
Use of a fuel which is low in quality or use of an inappropriate fuel additive may cause engine damage. ...