How to Clean a Dirt Bike Air Filter (and Oil the Foam Correctly)

The overall procedure includes the following steps:

1. Removing the air filter
2. Inspecting the filter for obvious defects
3. Cleaning the filter
4. Oiling the foam filter
5. Reinstalling on dirt bike

It’s important to note that the air filter uses a polyurethane inner and outer piece which cannot be separated. A dirty, water-soaked, worn-out, or defective air cleaner will allow dirt, dust, mud and other impurities to pass into the engine. Not good. This will destroy your bike.

Also, it’s important to note that whenever you’re washing your bike – make sure not to get water and dirt down your exhaust pipes, as this will also destroy your bike. I like recommending the use of an exhaust plug on your dirt bike whenever cleaning it, however there are DIY options out there as well.

Remove the Air Filter

Remove the seat so that you can get to and see the air filter inside of the air box and then remove the retaining bolt and washer.

Now you will be able to fully remove the air filter from the air box. You will also want to remove the skeleton/framework that holds the foam and keeps it in shape.

Inspect Air Filter for Damage

With the air filter foam out and free from the frame and air box, you should inspect it for any damage. You are looking for any split seems, tears (no matter how small) in the foam, deteriorating rubber seal, etc. If you find any, I strongly recommend you throw the foam filter away and spend the $20-30 to buy a new air filter. I like the Twin Air filters. You don’t want to mess around with this.

If the filter looks good, proceed with cleaning it. If it’s not, no need to spend the time cleaning something that you’re going to just throw out.

Clean the Air Filter Foam

Wash the air filter in a clean, non-flammable (NOT GAS), cleaning solvent. I like this air filter cleaner & oil kit.

Once you’ve removed the majority of the dirt and grime, wash the filter in warm, soapy water. Squeeze the filter thoroughly to clean out and then rinse thoroughly with clean water.

Set the foam aside and allow to dry completely.

Clean the Air Filter Frame & Air Box

While the foam is drying, clean the frame that holds the foam as well. Depending on how dirty it is, you may be able to get away with using just the soap and water mix.

Also, you’ll want to inspect the air box and carefully wipe it out clean. Make sure not to allow dirt or debris to fall down into it.

Oil the Foam Air Filter

After the air filter foam has dried, apply the foam filter oil, starting from the inside.

Factory specs call for 1.7 US oz on most bikes, so just under 2 oz. Basically, you want the filter to be completely oiled all-the-way-through, and spread evenly throughout the foam.

Reinstall in Air Box

That’s it!

Put the foam filter back into the frame, put the unit back in the air box, reinsert the bolt and tighten down.

How Often Do You Need To Clean the Air Filter on a Dirt Bike?

It depends. What an answer, right!? 😉

In reality, cleaning your filter after every ride could be excessive or appropriate – depending on the conditions.

If you are at the track pounding laps and sucking down dust for a few hours then yeah, you’re going to want to clean your dirt bike’s foam air filter.

However, if it’s just you and a buddy (or just you) and you went out for an easy cruise up the mountain to take advantage of the tacky, non-dusty, non-muddy terrain, then you can no doubt get away with not cleaning the filter after every ride.

I like to have two filters; one in the bike and a clean one ready to go. If you’re looking to pick up an extra filter, check out these Twin Air filters. They’re solid.

Most manuals will recommend “servicing frequently” depending on dust and/or rain as well as how often you’re full throttle on the bike.

A good average is every 2-4 rides.

I hope this makes your job a little easier and more clear. Now it’s your turn.