Cleaning Your Motorcycle’s Air Filter: How And When To Do It

It is a fairly simple task that really helps your engine to keep running efficiently. That’s because a dirty air filter can have a negative impact on engine and combustion performance.

Conversely, a clean air filter in good conditions will improve the bike’s performance and can optimize fuel consumption.

In this article, we will focus on the following:

1. what an air filter is and what it does
2. how to tell when the filter needs to be cleaned, and
3. how to clean it.

But that’s not all. One very important thing, indeed, it’s to recognize when change the filter is required. Actually, if you use your bike a lot or do motocross, sometimes simply cleaning the filter is not enough to improve the overall health of the engine, and the filter needs to be replaced.

Keep reading.

What does a motorcycle air filter do? 

The air filter is an essential part of a motorcycle’s fuel system because it allows the engine to “breathe” and to function properly.

A motorcycle engine works by burning a mixture of gasoline and air in a very precise ratio.

First the air passes through the filter, after that it is mixed with the fuel, then it reaches the combustion chamber, where it starts the engine and makes it run.

So, essentially, the role of the air filter is to clean the air and collect all the impurities suspended in the air, such as dust, sand, debris, and smog. If these foreign particles succeeded in getting past the air filter, they could impede combustion and damage the engine. 

What does a motorcycle air filter consist of?

Normally the filter consists of two parts. First, there is a more solid part, which is typically a sheath or a net. This more solid part supports the second one, the filtering element itself, which can be made of the following:

• paper,
• sponge, or
• fabric or cloth.

Different filter models come in different shapes. There are filters that are pleated (accordion style), rectangular, conical, cylindrical, and so on.

The filter is placed inside a box, which in turn is housed in the rear of the bike, on either the left side or the right side depending on the bike model. In appearance, an air filter is a medium-sized black box that is screwed or bolted shut and mounted near the intake ducts for the engine.

When the air filter is dirty or needs to be replaced, that can have an impact on engine performance.  That is why it’s very important that you take care of the filter and make sure to clean it.

Before we explain how to clean a washable air filter, in the next section we will discuss the most obvious signs that a filter is in urgent need of cleaning.

What are the first syntoms that a motorcycle air filter is dirty?

People often forget to check the condition of their motorcycle’s air filter until it is too late.  And when a filter has deteriorated too much overall, the best thing to do is to replace it. 

But before you reach the point where you have to change your bike’s air filter, it is important that you know in detail what the warning signs of a very dirty filter are.

When an air filter becomes heavily clogged, less air reaches the engine’s intake system. That inevitably causes a distortion in the ratio of air to fuel that powers the engine. 

When there is not enough air but too much fuel, the fuel cannot be completely ignited during combustion, and this reduces the power of the engine.

In the short term, you might notice the following syntoms:

• increased fuel consumption,
• slow throttle response,
• loss of response and power at high rpms,
• a telltale clogging noise when starting the engine,
• black exhaust gas, and
• overheating of the engine.

In the long run, if the filter doesn’t get cleaned, you could face much more serious problems, such as the following:

1. premature and unnatural wear on pistons, rings, spark plugs, etc.,
2. dirt accumulation on the throttle valve and/or the mass flow sensor, causing rpm instability, hesitation, and power loss,
3. clogging of valves and injectors, and
4. seizing of the engine due to debris buildup in the combustion chamber.

So, why risk wrecking your engine? Although cleaning the motorcycle’s air filter is a task that needs to be done meticulously, it is so simple that anyone can do it. By cleaning your filter, you can restore it to proper health in just a short time.

To find out the best way to clean an air filter, just keep reading, since we explain it in the next section.

How to clean an air filter that has become dirty from gasoline 

Before actually beginning to clean your bike’s air filter, you first need to take a look at it. When the engine is cold, open the box containing the filter. Remove the filter and look it over.

If the filter is broken, then your only option is to replace it. But if it is simply very dirty and clogged with debris, or is soaked full of water, gasoline, or oil, you don’t need to replace it immediately but can instead clean it.

In any case, you should clean the filter regularly. In many cases, the owner’s manual from the bike’s manufacturer will tell you how many kilometers you can travel between cleanings. 

As a rule, the filter needs to be cleaned roughly every 1,500–2,000 km. However, if you use your bike off-road, then you should check your filter — and clean it, if necessary — after every heat.

At Athena, we recommend you to check your filter frequently and either clean or replace it, especially if you ride your bike on particularly dirty, bumpy, or dusty roads.

In the case of filters made of foam, cotton, or similar fabrics, washing the filter and greasing it for use is quite easy. The following is the correct way to refurbish these kinds of air filters.

1. Remove the cover of the box that houses the filter.
2. Take the filter out of its housing compartment.
3. Spray a generous amount of detergent on the filter, and then let the detergent work on the filter for about 10 minutes, at which point the visible dirt should be dissolved.
4. Rinse the filter in low-pressure running water to remove all traces of dirt and detergent.  If you think it necessary, you can repeat this step a few times.
5. Let the filter dry completely.
6. When it is completely dry, saturate the filter with special lubricating oil and let the oil soak in for at least 20 minutes. Repeat this step until the surface of the filter looks red, like the color of the oil. If there is any excess oil, be sure to remove it.

That last step is very important because the oil helps the filter to filter out and hold all the impurities better. At this point, the only thing left to do is to mount the filter back in place. 

However, if it is a motocross bike, then make sure that you also clean the filter cage and the guide bolt well before you remount the filter. 

If your bike’s air filter is extremely dirty with oil or gasoline, or if the bike uses a traditional paper filter, then we recommend that you replace the filter rather than clean it. 

Attempting to wash a paper air filter or clean it with compressed air could reduce its ability to filter. To avoid this risk, change paper filters at least twice a year, just to be safe.

How often should other types of air filters be replaced? To find out, read the next section.

How often should you change your bike’s air filter? 

How long a filter will last and how efficiently it will be able to filter can vary depending on a number of factors, such as the ones listed below.

• The quality and model of the filter you use.
• The roads you usually travel on.
• Where you park your bike. (If you park your bike in a place that is dusty and exposed to the elements, you might have to replace the filter more frequently.)
• How often you maintain your filter.

That said, it is possible to give some figures in round numbers. For example, if you normally ride on paved city streets that are fairly clean, then your filter might last for up to 30,000 km. On the other hand, if you live in a dusty area or ride on dirt roads, that will reduce the figure by 15,000–20,000 km.

To know for sure when it’s the right time to replace the filter, we recommend that you periodically check the maximum number of kilometers that the bike’s manufacturer has specified in the user manual, and when you reach that number, we suggest you change the filter.

In general we can say that it is a good idea to change the air filter every 6 months, especially if there are conditions present that tend to wear out the filter quickly. Naturally, how much a new filter costs varies depending on the model and the size, but new filters typically cost between 7 and 15 euros, with filters for street bikes costing a bit more. Replacing a filter is easy, so you can do it yourself.

If the time has come for your motorcycle’s filter to be replaced, visit Athena’s website.  In our motorcycle parts section you’ll find a full line of filters at truly competitive prices. 

Our filters are top-quality and fire resistant, and are made with double-layer, polyurethane, open-cell construction that meets ISO 3795 requirements. This kind of structure guarantees optimal combined filtration and perfect air flow in all usage conditions.