Come to think of it, all air filters suck air. The problem is that some of them suck more than air. Not good!
If you are an off-road rider you should service your air filter in a timely fashion or you may start sucking dirt at some point. Even if your multisurface motorcycle is kept on pavement most of the time, a neglected air filter can cause you trouble. You may ask, “How can that be?”
The DR-350’s, DR-650’s and KL-650-A’s I’ve ridden (over 500,000 miles since 1990) come equipped with foam air filters made of cheap material. I learned long ago to use the factory air filter until it needs replacing and then discard it. If you attempt to clean and oil them too many times, the foam material will break down and ultimately get sucked right into your engine.
Way back in 1990 I sent my KLR-650 air box to Uni-Filter so that they could create a filter element for the KLR. In return, they shipped my air box back to me with the first two Uni-Filters ever made for the KLR. Even though Uni-Filter uses the best filter foam and adhesives, I discard the filter before the material breaks down. Particles of foam rubber are not good for the carburetor or the combustion process.
Although I use Uni-Filters in both my multisurface and paved surface DR’s, I prefer the K&N air filters when I’m riding in a dust free environment. The trouble is K&N ‘blew it” on the engineering phase of the project. Fortunately, I can fix the problem with a little machine work, a drilled hole, some washers and a fastener. With this small tweak the K&N filters are the best choice for my pavement DR. Why? Because they are easier to clean and oil than foam, and they breathe much better, allowing me to get full benefit from my Vey de la Cruz porting.
I don’t intend this article to be a commercial for Uni-Filter or K&N. My goal is to convince you that DR and KLR stock air filters are generally not high quality or permanent. Use them until they are ready to be replaced and then install a unit made of better material and held together with a superior adhesive.
Oh, and keep them clean!