When it comes to air filter maintenance, I personally recommend changing and cleaning the filter after every ride. This ensures the bike can breathe freely and take in only clean, filtered air each time you hit the trails. A fresh, clean air filter optimizes engine performance.

Removing the Old Air Filter

Removing the old air filter is the first step in this maintenance process.

• Start by taking off the air box panel to gain access to the filter. You'll see the old filter situated inside. Before pulling it out, release the plastic tabs on the bottom and top that secure it. This will allow you to lift and detach the air filter from the filter cage mounted inside the air box. Be gentle as you maneuver it out so as not to rip the foam edges.

• Now you've got the air filter removed and with a four stroke air filter you can see the wire mesh inside. On the two stroke you don't have that. It helps to stop any dirt being dragged through in to the air booth.

• You can unhook the two little lips on the airfilter and pop off the filter from the air filter cage.

Now you're ready to oil and install the new filter without worry of contamination.

Cleaning the Air Box

Before installing a new air filter, it's important to thoroughly clean out the air box. Use a degreaser like the A9 Racing All In One Spray and rag to wipe away any dirt, moisture, or debris inside the air boot and surrounding air box. Make sure to carefully inspect inside the throttle body as well, as dirt can get dragged through past the air filter.

Don’t forget to remember to remove any shop rags or tissues that may have been stuffed in the air boot when washing the bike. Many riders cover the air box opening when cleaning their bikes, shoving a rag inside to prevent water intrusion. However, it's easy to forget to remove this debris which can cause starting issues with a new filter. So always double check for any foreign material before bolting the air filter back into place.

Taking a minute to properly clean the air box will allow your new filter to perform optimally.

Oiling the New Filter

Oiling the new air filter is a key step to ensure no dirt sneaks past into your engine. For this you can use the A9 Racing Air Filter Service Kit. This contains everything you need

• A9 Air Filter Oil

• A9 Air Filter Cleaner

• A9 Air Filter Cleaning Bucket

• A9 Air Filter Oil Bucket

• Dirt Grill

And separately I’ve got a new MX Twenty Air Filter. This one is dry and oil up ourselves. You can also buy pre-oiled filters.

Now put on your gloves and follow these steps to oil the new filter:

• Start by submerging the entire foam filter into a bucket filled with 100ml of filter oil. It’s critical to coat all surfaces of the filter foam with oil, so take care to fully soak it.

• Once submerged, massage the oil thoroughly into the foam, squeezing it between your hands. Really work it to saturate deep into the filter. You’ll likely need to flip it inside out as well, coating both sides. The oil creates a sticky barrier that traps dust.

• After it’s fully coated, wring out any excess oil by squeezing the filter. You don’t want drips inside the air box.

The filter should now have an even coat ready to block debris when installed.

Reinstalling the New Filter

First, clip the filter back into the filter cage, feeding the two rubber nipples on the end into the corresponding holes. Make sure the filter lines up properly and fits snugly within the cage.

Next, insert the cage back into the air box, guiding those rubber nipples into their fittings inside the air box. Make sure the air filter sits nicely in the boot. Closing any gaps. I intend to use my hand all the way around the air filter to double check this. Now the air filter is installed.

With the gloves off you can put the cage back on. You may need to give the cage a gentle tap to fully seat it. If fitted correctly, the filter will now be securely installed and ready for use.

Cleaning the Old Filter (Optional)

While replacing air filters each ride is ideal, constantly purchasing new ones can get expensive. Luckily, you can reuse old filters by properly cleaning them.

• Start by putting the A9 Air Filter cleaner in to the A9 Air Filter cleaning bucket. Make sure the dirt grill plate is placed on its feet in the bucket.

• Now submerge the used filter ( top down ) in an air filter cleaning solution. Pushing it down onto the dirt grill plate allows the solution to draw out embedded dirt and separate it from the filter foam. Let it soak for a few minutes.

• Once done soaking, lift out the filter and thoroughly rinse off the cleaning solution. Avoid dripping excess fluid everywhere. With the dirt rinsed out, hang or lay the filter out to completely air dry before oiling and reusing.

This cleaning process extracts significant life out of used filters. Though inspect them for cracks or heavy discoloration and replace when overly worn.

Inspect them for cracks or heavy discoloration

Even after cleaning, there will come a time when you need to replace your air filter. Check the filter carefully for any cracking in the foam or heavy discoloration. This often happens on the outer or inner surfaces after extensive use. The filter I demonstrated still looked in decent shape, with only some minor marking from regular rides. But if the foam integrity becomes too compromised, dirt and debris will get through so a new filter is required. Still, with proper maintenance, most filters can be cleaned and reused many times before needing replacement. It comes down to inspecting closely and using your best judgment on when performance will start to suffer. With a quality cleaner kit and routine care, you’ll get the maximum lifespan out of your air filters.

Final tip: 10 air filters at once

Taking the time to change your filter after every ride and thoroughly cleaning used ones before reuse pays dividends in the long run by allowing your engine to breathe freely. My way of handling this is having about 10 air filters clean so after every ride I can quicky replace it with a fresh one. Then I clean all 10 at once.

Keeping your dirt bike's air filter properly maintained is a quick and straightforward process that any rider can easily tackle themselves. As I demonstrated in this article, removing, cleaning, and replacing the air filter can be done in a matter of minutes with some basic tools and supplies.

By following the step-by-step filter maintenance process detailed here, you can ensure your bike always has a clean air intake, leading to optimal performance each time you hit the trails. Proper air filter upkeep gives you peace of mind that your engine is operating at its peak while you focus on the ride ahead.

Author information

My name is Charlie Frost, and I'm no stranger to the adrenaline-fueled world of extreme enduros. Starting my journey at 19, I seamlessly blended trials and enduro racing, honing my skills through youth events and extreme races like the Tough One and Erzberg. When I'm not tearing through rugged terrain, you can often find me in front of the 24MX camera, sharing my passion and insights with fellow riders, as we delve into the exhilarating world of off-road racing.