3 Types of Motorcycle Air Filters and How to Tell When to Replace It.

Your motorcycle engine needs to intake air in order to run properly. The air filter’s job is to purge the incoming air of dirt and particulates. Without the air filter the engine would be left unguarded to dirt and debris entering the cylinders causing wear and tear on the engine internals.

A clogged or dirty air filter will weaken your engine’s performance and fuel economy. That’s why it is important to follow your maintenance manual on air filter replacement or cleaning. Most motorcycles recommend replacing or cleaning the air filter every 10,000 – 15,000 miles.

Three Different Types of Air Filters

There are three types of motorcycle filters: paper, oiled cotton gauze, and oiled foam. Most motorcycle’s OEM filters are disposable filters made of paper. Paper filters are not reusable. They are designed to capture as many particles as possible

Paper Motorcycle Air Filter

Normally these filters have small pores which can plug up quickly and restrict airflow. Although paper OEM filters do a good job of stopping particles from entering the engine, they can be constrictive. Aftermarket filters have several key advantages. One of those advantages is that they can offer increased airflow into the engine while still protecting it from dirt and debris. The other advantage is that they are normally reusable. Another type of filter is the oiled cotton gauze air filter.

Oiled Cotton Gauze Air Filter

This oiled cotton gauze air filter is washable, reusable and designed to last the life of the motorcycle. These air filters consist of multiple sheets of cotton gauze layered between sheets of aluminum wire mesh. This media is also oiled to enhance its filtering capabilities and performance. The end result is a reusable air filter that provides high amounts of flow to the engine and is built to last for the life of your motorcycle.

The last type of air filter is the oiled foam air filter. Oiled foam air filters are known as depth filters. The foam is usually an inch thick. The air molecules will have work its way through the oil coated foam before it can get to the engine.

Oiled Foam Filter

The oil coating works to stick to and stop any dirt or particles other than the air that would otherwise harm the engine. These types of filters are very effective in cleaning the air as long as the oil hasn’t dried out.

How Long Does an Air Filter Last

An air filter’s lifespan depends on the environment that it operates in. For instance a motorcycle’s air filter in a dusty desert environment will last much shorter than an air filter in the Midwest area. Most experts recommend changing or cleaning your air filter every 10,000 to 15,00 miles if you have a paper filter or an oiled cotton filter. If you ride your bike on dusty roads be sure to change or clean the filter closer to 10,000 miles than 15,000 miles.

Most bikes that use foam filters operate in extremely dirty and dusty environments. That is way they need the superior filtration that the thick oiled foam filter provides. The disadvantage to this filter is that it needs to be cleaned far more often. These filters most often scene on dirt bikes and atvs should be cleaned after almost every ride. There are different techniques for cleaning foam filters, but if you’re looking for a good guide, check this article out here.

Signs you Need to Change or Clean Your Air Filter

There are different warnings and signs that your motorcycle will give you when its time for air filter maintenance.

  1. The Air filter is dirty. The most obvious sign its time for maintenance is that the air filter is visually dirty, or the oil dry. Some air filters are external and can be easily seen while others are hidden under a housing that only takes a few bolts to remove. Its a good idea to check on the filter ever so often.
  2. Reduced Fuel Economy (Carbureted Motorcycles Only) . Motorcycles are very efficient, but if your motorcycle mpg drops significantly this is a sign of a problem. The problem could be caused by a clogged or dirty air filter. This problem is only caused on motorcycles with a carburetor. Fuel injected motorcycles will adjust for dirty air filters, and you most likely won’t notice a difference in mpg.
  3. Reduced Power. Reduced horsepower can be caused by a lack of air getting to the engine. This can again be caused by dirty and clogged air filters. If you’re bike has lower power and is running rich (high fuel low air), it would be a good idea to check out the air filter.
  4. Cylinder Misfire. Air filters can also cause misfires in the engine. If the engine isn’t getting enough air, unburnt fuel will exit the cylinders in the form of soot residue. This residue will coat the spark plugs hindering their ability to function. This can even cause an engine misfire or difficulty starting the bike. If this occurs, the spark plugs will have to be cleaned or replaced, and the motorcycle’s air filter will need maintenance.

Can Aftermarket Air Filters Improve Motorcycle Performance

Aftermarket air filters could improve or hurt performance depending on the filter. While that answer isn’t very helpful, it is important to research each filter before you install it on your bike. Studies have shown that aftermarket air filters can increase horsepower by as much as 3.8%. However inexpensive filters or even some high performance filters can have reduced filtering capability compared to their OEM counterparts.

Another point to make is that many aftermarket air filters will increase your motorcycles horsepower, but these filters have to be maintained/cleaned properly and on schedule. A high performance air filter will not do your bike any favors if it is never cleaned.