The air filter on your bike handles the massive responsibility of preventing sand, dirt and foreign materials from entering your dirt bike's engine.
It can only perform its job properly if it is kept clean. If allowed to become dirtier than Arnie in his prime, it won't be able to keep out all the dirt. Plus your bikes performance will be affected by the lack of air flow through the mud-caked breathing holes in the filter. There is nothing exciting about cleaning the air filter, but if you neglect to do it on a regular basis you can cause some real damage to the piston and barrel and also block up the carby.
What your filter looks like after a few hours riding in the dunes! Before cleaning and after cleaning shots.
Here are 7 easy steps to cleaning the dirty bugger:
I use and can recommend No Toil biodegradable filter cleaner and filter oil.
Certain brands/models, like KTM, have the air filter located on the side of the bike or in other unique places. The process of cleaning the filter remains the same. Just make sure you put it back in properly.
Tip: Don't do what I've done here and use your bare hands. Use some throw-away latex gloves as the chemicals in these products aren't good for you long term.
When cleaning the filter, always check for holes or tears. If there are any replace it immediately! A new filter is less than $30. Don't risk damaging the engine or gunking up the carby because you are lazy, or you'd rather spend the money on a cold dozen for after the ride.