Air Filters: What Many Overlook, But Shouldn’t

Many riders are quick to change the oil in their bikes, lube the chain, check the air pressure in their tires, and even replace the top end. However, one aspect many riders, and mechanics alike as well at times, overlook the air filter, and this can cause greater trouble than not changing oil. A dirty air filter, or air filter system for that matter, can lead to a poor running bike in terms of a rich condition, thus possible fouling of spark plugs, or it can even lead to engine seizure in worst case scenarios. The air intake system uses an air box, air filter, and air box drain, and all of them must be maintained, and often, for your bike to operate at its full potential. However, and most importantly, what stands between you and a properly running engine is a simple piece of foam that is fully covered in a thin, yet liberal, film of oil. This piece of foam, and a thin layer of oil, is one of the most important aspects protecting your engine from harmful debris and expensive repairs.

This filter is doing it’s job of trapping dirt. Notice all the dirt inside the air box. Reason for cleaning the air box.

Air filters should be cleaned after each ride for best performance, especially after rides in extreme dry, dusty conditions or muddy, wet conditions. Each time the filter is cleaned you also need to check the seams for tears or separation, and also check for extremely dirty areas that may need special and extra attention. Most filters are bonded together with adhesives, and over time the seams will split and the foam starts to break down. As a rule of thumb, most filters should be replaced after 15-20 cleanings, but can last longer if you take proper care of them. The higher end air filters will usually last far longer than cheaper made ones, so buy the best you can.

The higher end filters are usually what is known as a “two stage filter system”, and we agree with many that these are far better than other single stage systems on the market. The reason for this is that a two stage system will have what are basically two filters in one. There are two foam filters, one fitting into the other as a rule, and this gives you what amounts to double protection that exceeds single stage system that usually consist of a single, thicker piece of foam. In our opinion, three of the best filter systems on the market are DT1 Filters, Twin Air, and Uni-Air. There are other two stage filters out there that offer great protection and function, just do your home work when making your next air filter purchase. We happen to use each of these listed above and can say that there is not much difference in one over the other for offering great engine protection and serviceability.

Dirty air filters ready to be cleaned.

Dirty air filters ready to be cleaned.

Although, how do you clean your filters so that they last longer? There are several cleaning agents on the market to help you with this; however, some only work with their own products, so it is wise to read the descriptions before you buy. However, one of the ways we have found to clean air filters works very well, does not damage the filters, and also is cheaper than many products on the market.

Pour your selected cleaner onto the filter. Make sure you have a clean catch pan to contain the cleaner.

Pour your selected cleaner onto the filter. Make sure you have a clean catch pan to contain the cleaner.

What we have done when in a pinch, and we have done this for years without issues providing you follow all the steps, is to use low odor mineral spirits to clean the filters. You want to use low odor as it is less stringent on the filter, yet it will still clean the filter without doing damage to the seams or the foam itself, so make sure to use low odor mineral spirits only for this. You will need a couple sets of simple exam gloves, two small 1 gal. buckets, your favorite filter cleaner or low odor mineral spirits, and a good supply of warm water as needed. We use a large utility sink usually found in laundry rooms of your home either made of plastic or metal.

Work the cleaner into the filter by squeezing it. Add cleaner as needed.

Work the cleaner into the filter by squeezing it. Add cleaner as needed.

While wearing simple, yet effective, exam gloves that can be bought in any local pharmacy or hardware store, We will first separate the foam inserts (some two stage filters are two pieces), and then with a clean bucket we will take the filter cleaner or low odor mineral spirits and fill the bucket. Next, we submerge the filters into the cleaner and then squeeze, never wringing or twisting, the cleaner into another clean bucket. We do this until we have thoroughly cleaned the filter, and then we simply take warm water and dish detergent to wash & rinse the cleaner from the filter. This usually takes around 10 minutes to do, and then we allow the filter to air dry while we strain the cleaner via a terry cloth so that we get the dirt from the cleaner and we are able to reuse it again. The filter will usually be completely dry, if left in the sun, in less than 30 minutes, and it will take a little longer on a colder day or if inside your home or shop. Never use heat to dry a filter such as clothes dryer, a hair dryer, or heater. These can do damage by melting the foam or seams and thus ruining your filter.

Using dish soap and water for final cleaning.

Using dish soap and water for final cleaning.

Work the soapy water into the filter for final cleaning. Next rinse the filter with clean water.

Clean air filters sun bathing until dry.

Clean air filters sun bathing until dry.

While the filter is drying, and after removing your air filter, we take a flash light and inspect the inside of the air box behind the filter for any dirt which would indicate a leak. We will then clean the intake itself by taking a clean, wet rag and wiping any excess dirt and debris away from the opening where the filter covers. Then we will cover that with a cover made of hard plastic to keep water and other debris from out of the engine. Now I can use a garden hose to clean out where the filter is housed and also make sure that our clean filter does not go back into a dirty housing. Every few rides we will remove the intake completely and clean it with a hose & soap and wipe it down thoroughly to make sure we always have a properly prepared and clean intake track.

Inspect the intake track for dirt.

Inspect the intake track for dirt. Best to use a small light to shine down into the intake area.

Air box cover installed.

Use your favorite cleaner and a small brush if needed. Use the hose without nozzle to rise the air box.

Use your favorite cleaner and a small brush if needed. Use the hose without nozzle to rise the air box.

Once the filter(s) are dry and again using exam gloves and a clean bucket, we will use our favorite or suitable air filter oil to saturate the filter. Once the filter is fully saturated, we again squeeze out any excess oil, again making sure to never wring or twist. The oil that is left we can use again for this same purpose, so be sure to keep it and do not discard it.

Saturate the filter with oil.

Work the oil into every part of the filter. Make sure the enitre filter is oiled.

Squeeze the filter of any access oil into your clean catch pan. Never twist the filter.

However, if you want a quicker method, and do not mind spending a bit more money, one of the more popular oiling and cleaning products on the market these days is a product by the name of No Toil. This system has oil, cleaners, and even pre-oiled filters for you to use. However, and as we stated before, this system only works well with itself and not other systems out there. You can use it on any filter, but No Toil cleaner will not work well, if at all, on other products similar in nature. See No Toil cleaners and oil work together to release the dirt and oil from the filter. Also, many filter companies will also make their own cleaning and oiling systems, such as DT1 Filters offers a biodegradable cleaner and oil for maximum protection and it’s environmentally friendly and is a product that we enjoy using, so check on those as well. We can say that DT1 Air Filter cleaners and oil works best when used together just as the No Toil, even though DT1 doesn’t advertise that they should be used together.

When we go to replace our filter(s) back onto the intake, we will apply a thin, but thorough, layer of grease around the edge of the filter where it contacts the intake so that we have a sealed system that will not allow any debris into the intake.

However, never clean the filter with gasoline or diesel fuel due to these being flammable and they also attack the adhesive used to bond the filter parts together.

Tips For Air Filters

To help make air filter maintenance easier you can have an extra two or three filters already cleaned and oiled in separate plastic bags to help you keep yourself clean as well as the filters themselves. Having a box of disposable gloves are great for keeping your hands clean while applying filter oil or changing filters, and they also serve other purposes like covering your end cap on your silencer when you wash your bike.

Another good buy are filter covers. Filter covers are a cloth like cover that slips over the air filter and it extend the service intervals of the air filter. Most have a strain that can hang outside the air box and as needed you just pull the strain to remove it during those super dry dusty rides and underneath is a clean air filter ready to finish the race. One last item, don’t forget to clean the air filter cage and retaining bolt with contact cleaner.

We hope this helps you out with your filters and allows you to keep your bike running to its best potential. Keep watching for more tips and tricks from Dirt Hammers, and thanks for reading.

The Hammer Crew

Ryan Hackney

Richard Hughes



  • Alex

    Nice write up! Clean filter, happy bike, happy rider.

  • hughes2224

    Thanks Alex.
    Hope to get our clean air filters dirty this weekend.