Dirt bikes may seem to many to be quite simple machines, but there are many important components that need regular care and maintenance for your dirt bike to function properly. One of these components is an air filter, but many riders may wonder if they can ride their dirt bike without one.
You can ride your dirt bike without an air filter, but you really shouldn’t. Air filters are vital components of dirt bikes, and they ensure your engine only receives clean air – to run efficiently – and to keep it free from debris that could seriously and permanently damage the engine.
While it is possible for your dirt bike to run without an air filter, it’s highly recommended that you never do this. Below, we’ll go into more detail about just how important dirt bike air filters are, how they work, and how you can properly clean and replace your dirt bike’s air filter.
What A Dirt Bike Air Filter Does
Clean air is imperative in your motorcycle’s performance and longevity. If oil is the life’s blood of your engine – and it is – keeping your air filter well serviced keeps the motor’s heart and lungs healthy. Your engine is basically a complex air pump. It also needs fuel and ignition to run, but you’re going nowhere without air in the equation.
So, we have to have air. And as the spark plug goes bang and ignites the fuel, the engine sucks in air through the motorcycle’s intake at a considerable velocity. That previously mentioned fourth component, oil, creates a thin film that allows your piston and your cylinder to peacefully coexist.
Your air filter prevents this peaceful coexistence from being disturbed, by ensuring that it’s only air that gets into the engine – no debris. But how do air filters do this?
Why Do Dirt Bikes Need An Air Filter?
First, let’s be clear that all engines need an air filter. Your car, your truck, your lawn mower, your leaf blower – if it is a machine powered by an internal combustion engine, it requires an air filter to ensure its longevity and proper operating condition.
Most showroom stock automotive application filters are paper, and are designed to be periodically replaced. But unless the owner lives down 30 miles of gravel road, most drivers ignore this maintenance. And as long as most travel is via paved road, it’s usually not an issue.
Putting The Dirt In Dirt Bike
But for us riders it’s all in the name: Dirt bike. By design, we ride in the dirt. In the mud. In the sand. In conditions that bring you and your machine into constant contact with debris that, if ingested, will lay waste to your engine’s cylinder wall, piston, rings, and worse in short order.
Even tiny particles of dirt can effectively act as sandpaper inside an engine spinning at thousands of revolutions per minute. Happily, dirt bikes are almost uniformly equipped with washable closed cell filters that are designed to be regularly removed, cleaned, re-oiled, and reinstalled.
It doesn’t take long for an engine breathing dirt, dust, and sand to expire. Repairs will be expensive, even if you can do the work yourself. That’s why the correct care of your air filter is essential.
How Do I Know If My Air Filter Needs Cleaned?
Regular cleaning is normal maintenance. Serious off-roaders will clean and/or replace their air filter every ride, or at least every day of riding. More casual riders can be a bit more lax, regular cleaning of your air filter is definitely not a bad idea regardless of how often you ride.
Sometimes you can tell by looking at a filter that it needs cleaning, but there are also two areas of coverage to be concerned with, and only the surface layer is visible. If the outer part of the filter is covered in dirt, dust, and debris, then it obviously needs cleaning.
But don’t forget that an air filter also has depth. Even a filter that looks clean on top can have small particles of dirt embedded in the foam below the surface. That’s why regular maintenance is just the best way to go about it. But how should you clean your dirt bike’s air filter?
9 Steps To Correctly Servicing Your Dirt Bike’s Air Filter
1. Remove Your Air Filter
There is no one way to remove your dirt bike’s air filter, as there is a small bit of variance in placement and attachment between brands and models. But for the most part, your air filter is located either underneath your seat or beneath one of your side covers.
Seats generally have a bolt on either side at the rear, and a hook up front that slides into a collar bolted into your tank. Side panels may simply snap on and off – be gentle, and make sure that they do just snap off before you start prying.
There may be screws or bolts affixing the bodywork. In any event, after getting to the air filter, a thumb screw located in the center of the filter is most often used to secure the filter and its cage to the intake. Be very mindful to avoid knocking or dropping dirt or debris into the air boot beneath.
The filter itself is made of foam that would not hold its shape under the vacuum of intake created by a high-rpm off-road machine. Thus, a “cage” is used inside the filter to prevent it collapsing on itself. You’ll remove the cage from inside the filter to wash the foam.
2. Clean Your Air Filter Using Your Chosen Cleaning Agent
Using a bucket or tub of some sort, completely submerge the filter in your cleaning agent of choice. Swirl it around, and knead the foam in order to work the dirt out of the foam. The best choice of cleaning agent is probably kerosene, as far as commonly available cleaners go.
Mineral spirits are also acceptable. Those agents will be less volatile and damaging to the foam and construction. Still better yet, however, is any number of products made specifically for the task at hand. A wide variety of air filter cleaners are available at motorcycle dealers and other powersports suppliers.
Your air filter is saturated in special oil. It’s the oil that actually catches and collects the dirt and dust, not the foam. The foam simply holds the oil. While hot water and dish soap can release most of the debris in a dirty filter, it’s best to go with something a bit stronger to force the oil particles to separate.
3. Let Your Air Filter Dry
Once you’ve thoroughly cleaned the air filter, remove it from the cleaning agent and allow it to air dry. This shouldn’t take long, as most cleaners will evaporate quickly.
4. Wash The Filter Again
Wash the filter again, this time in hot soapy water. You might think a second wash is redundant. However, the amount of additional dirt you’ll find in the bottom of that bowl will give you second thoughts!
5. Let The Filter Air Dry
Again, after the second wash, let the filter air dry. Blowing it out with compressed air can speed up the process, but easy does it. High pressure air can damage the foam. Shy away from throwing it in the dryer or using a heat gun. Heat will also damage the glue holding the filter together.
6. Clean The Air Box
Now, while the filter is drying, it’s a good time to clean the air box. Cover the air box inlet with a rag, tape, or an aftermarket cover designed for your bike. Then, using a combination of soap and water, and a bit of contact cleaner if needed (and compressed air if available), clean any debris from the interior of the box. DO NOT allow dirt or debris to enter the air boot.
7. Submerge Your Filter In Oil
Submerge the dry filter completely into your air filter oil of choice. Yes, air filter oil. It’s specific, and it’s important. It’s possible to substitute motor oil, but that’s ill-advised. Air filter oil is much thicker in viscosity and sticky, designed of course to specifically trap dirt.
Engine oil is designed first and foremost to be slippery. It’s also far too thin, and will slip right through the filter, into the bottom of the air box, and eventually onto the floor of your garage or driveway. That’s bad because it makes a mess. What’s worse is that your filter is no longer properly oiled!
8. Remove Excess Oil
Once the filter is completely saturated, remove it from the oil and squeeze out the excess as best you can. Do not wring or twist the foam, just squeeze, working from one end to the other and back until the excess runs off. Twisting can tear the web-like structure of the foam. Use paper towels or an old rag to blot out any remaining excess oil from the foam’s surface.
9. Reinstall Your Air Filter
Either reinstall the filter into your dirt bike, or put it into a sealed plastic bag for future use. Having at least one spare filter, already prepped from last time, means you can quickly just reinstall the clean one and skip the cleaning steps until after your ride, if you’re pressed for time.
But regardless of whether you plan to go straight out or not, remove the dirty filter, check the air box, and install the spare immediately. This allows you to take your time with the more tedious steps in the middle.
Dos And Don’ts Of Cleaning Dirt Bike Air Filters
Do Oil Your Air Filter Before Using It
Remember, it’s not the foam that catches the dirt, it’s the film created by the oil. Also, your dirt bike is tuned for a set amount of air to be delivered through the air box. An oiled filter delivers the right amount of air flow.
Do Be Gentle When Washing Your Filter
Excessive wringing and rough treatment can break down the tiny foam particles. This is seldom something you can see visually, but even small tears can compromise your filter’s effectiveness.
After following up with another gentle wash in warm soapy water, rinse and squeeze the filter. Folding is acceptable, and a second rinse is not a bad idea. Air dry the filter, or leave it in a well protected spot outside in the sun.
Do Thoroughly Oil Your Air Filter Before Use, But Not Excessively
Use an oil designed for the purpose. Soak the filter completely. Squeeze out the excess oil gently, but sufficiently. You can blot any excess oil with paper or cloth towels. Ideally, allow the freshly serviced filter a few hours to “cure” before riding. This is essentially just the oil becoming tackier, and therefore better at catching dirt and dust.
Don’t Use Gasoline To Clean Your Filter
When properly cleaned with the appropriate liquids, air filters will withstand nearly infinite cleanings and still be useable. Conversely, repeated cleanings with gasoline will eat your glue and eventually your foam and require replacement.
Gasoline and parts cleaner type solvents will damage and age the foam, and will quickly attack the glue that holds your air filter together. Repeated washings in gasoline will sooner than later result in you holding unusable pieces of foam in your hands instead of a useable filter.
If you’re in a pinch or just stubbornly insist on using gasoline, at minimum wash the filter a second time in hot water and soap as soon as possible to get all the gas out of the filter before it harms the glue.
Don’t Use Heat To Dry Your Filter
Heat will harm the glue that holds the foam together. Compressed air is also iffy, as it’s very easy to damage the foam with high pressure air.
Don’t Overlook Or Underestimate The Value Of A Clean Air Filter
Your airbox is performance central for your dirt bike. Induction creates power, but induction of the wrong substances creates problems. The unimpeded flow of fresh air results in maximum horsepower and performance. A leaking or filthy air filter not only hinders performance, but it can also result in potential destruction of your dirt bike’s internals.
When To Replace Your Dirt Bike Air Filter
If you’re riding a relatively new, low hours machine, you can get countless hours of service from the original equipment filter assuming it hasn’t been damaged. High quality filters – which are thankfully generally provided by the manufacturers – can withstand hundreds of proper cleanings.
On the flip side, if your machine was previously owned, possibly neglected, and its maintenance history is unknown, replacing your filter immediately is probably best. It’s better to be safe than sorry, as air filters are far more affordable than engine components.
Which Products To Choose
Quality aftermarket filters are available from a variety of sources, and in a smaller variety of styles. Popular brands Uni Filter, for example, use a two stage foam system with an inner and an outer filter that are cleaned and oiled separately. These are often the choice of riders who spend their time in sandier conditions.
Twin-Air likewise uses a dual-stage foam, but theirs is a one-piece unit with the two foam layers bonded at the factory. Twin-Air also, along with others like Maxima, also offer pre-oiled filter units that are ready for installation right out of the package.
There are also many other brands available, each with its advantages and disadvantages, so shop around. But bear in mind it’s likely that a new filter from any reputable manufacturer is preferable to one that’s been cleaned countless times – or worse, never been cleaned at all!
While you can ride your dirt bike without an air filter, it’s definitely advised not to do this. Dirt bike air filters ensure that the correct amount of air gets into your engine for maximum performance, and they also ensure your engine doesn’t get damaged by dirt and dust.