A universal type air filter, commonly called a power filter, offers less intake resistance than the OEM air cleaner case version and better protection of the engine interior than the air funnel version.
The K&N filter, which is synonymous with this type of filter, is made of special cotton that is infiltrated with oil to prevent the entry of dust and debris. Therefore, regular maintenance is necessary because the filter becomes clogged when the mileage increases or when driving on off-road courses.
- Dirt accumulated in the pleats of the filter increases inhalation resistance
- Spray with a special cleaner and gently rinse with water.
Dirt accumulated in the pleats of the filter increases inhalation resistance
Removing the air cleaner case and installing a power filter reduces intake resistance and transforms the carb’s appearance into a sporty one. However, since the negative pressure generated in the venturi of the carb changes significantly depending on whether the cleaner case is installed or not, it is often necessary to change the settings.
The installation of a power filter is considered to be a custom effect in terms of both looks and performance in modifying the intake system. The OEM air cleaner box, which was developed with an emphasis on filtration performance to prevent intake noise and damage to the engine internals, does not necessarily bring out 100% of the engine’s potential. There may be a so-called stretch.
Nevertheless, a funnel specification that completely removes the air cleaner will certainly reduce intake resistance to near zero, but it will also allow dust and dirt to be sucked in as much as possible, causing wear and damage to the engine interior. This is where the universal type air filter, the so-called power filter, which can filter the intake air while eliminating the intake resistance of the cleaner box, comes into close focus. K&N, a pioneer and still the leading brand in power filters, commercialized the high-flow air filter more than 50 years ago, which is still used today.
This product features a high-flow effect, in which four layers of cotton gauze are stacked to rectify airflow and improve inhalation efficiency. Although layering gauze filters may seem to increase intake resistance, they are stacked to regulate turbulence. The air that the carburetor draws in flows faster and at a higher flow rate as the throttle opening is increased. Therefore, dirt accumulates in the cotton gauze of the filter, which causes intake resistance. Therefore, periodic cleaning is essential for K&N and other power filters. The timing for cleaning is not indicated by a clear mileage as is the case with the genuine air cleaner element. Unlike the filter element inside the air cleaner case, the power filter is exposed to the outside and can be exposed to rainwater depending on weather conditions or to dust from the wind while parked in the open air. As a rule of thumb, when the entire aluminum mesh holding the cotton gauze becomes black and dirty, it is time for cleaning. As described later, filter oil permeates the surface of the element, and the time when the oil on the aluminum mesh absorbs the dirt can be judged as the criteria for a decrease in air intake efficiency.
Spray with a special cleaner and gently rinse with water.
Spray filter cleaner. This cleaner is water-soluble and specially formulated not to damage the filter material. Be careful not to use parts cleaners or oil washes as they may damage the cotton gauze filter.
The cleaner that cleans the filter will remove oil and dirt and turn the filter black. The OEM air cleaner box opening is located under the seat and inside the side cover, which avoids dust and dirt to some extent, but the power filter is in direct contact with the outside air, so the amount of dirt and grime will be greater.
Filters soiled with sand and dust are cleaned with a special filter cleaner. If it is oil, parts cleaner or oil wash may be sufficient, but cotton gauze is delicate, unlike filter sponges made of polyurethane, so a water-soluble cleaner should be used. This cleaning procedure is for K&N filters. Filters made by other manufacturers use different materials and may require different cleaning ingredients, so follow the filter manufacturer’s instructions. After applying the water-based K&N filter cleaner to the filter surface, allow it to penetrate each part for about 10 minutes, then apply water from a water hose in the direction opposite to the airflow to push out dirt. If the filter is the type shown in the image, place the hose inside the tapered shape and run the water through it. If you apply water from the outside to the inside in the same direction as the airflow, you will push dirt into the cotton gauze. Filter cleaner only dissolves filter oil, not dirt or dust. Therefore, it is a prerequisite that solids on the surface of the filter be pushed away by the water flow.