K&n Air Filters

K&N Air Filters

EVALUATION

Better Filtering, Less Restriction and Easier Cleaning

Suzuki's new RMX motocrossers made a big splash with most owners but it didn't take long to learn the stock air filter caused more restriction than necessary. And extreme care was called for when cleaning and replacing the stock filter.

K&N has come to the rescue with replacement filters that make maintenance easier and less frequent. K&N filters are basically a thin gauze material sandwiched between fine screen wire and folded into pleats. A soft plastic material ties the foam and screen together at the ends, forming a good sealing surface at one end, a leak proof cap at the other.

Special K&N filter oil, available in spray or spout cans, is applied to the filter gauze and the sealing edge is greased before the filter is installed. Filter style and shape vary with the vehicle involved, each having its own design so stock air boxes are retained in most cases. On the new RMX, the filters fit perfectly in the airbox. Several things combine to give the buyer lots of product for his money. The first benefit is performance. Most engines have an instant increase in power due to lessened air restriction through the filter material. In fact, K&Ns airflow machine shows restriction through K&N filters on a stock RMX 465X airbox with the stock side covers in place, is cut in half. The restriction through the K&N filters is only slightly more than with no filters in place. K&N also has flow figures for the RMX with the side panels removed. Flow is only slightly restricted by the covers whether the stock or K&N filter is used. So much for chopping the covers up for improved performance, the difference isn’t worth losing the water protection of the stock covers.

The second reason for using K&N filters is the extended period between cleanings. The pleats greatly increase filtering area and the filter is designed to utilize the dirt that sticks to it for additional filtering. Thus, as long as the filter looks wet it will filter fine without cleaning. If you hate cleaning air filters, this is the filter to buy.

The K&N was easily installed and instantly gave better breathing. Air flow was so much better that we had to go to a richer main jet and higher needle, so the engine has gas to match its new air supply.

During the three months since then we found the other improvement, in that the bike has been raced and ridden in the dust and sand, no rain for eight months at this writing, and the filter has only needed cleaning and re-oiling once.

The filters are available at most motorcycle stores. Prices vary with application but are usually about the same as for a stock filter.