Onederer wrote on 04/06/08 at 12:46:59:I have a problem with noticable amounts of dirt getting past them. If I had a pure race vehicle that the engine was gona be torn down after x hours, then I'd run one, but on the cars and bikes I've used them on, after I run them for a while then look inside the intake, I have seen dust in there. I put on the stock filters, and no dust. I threw them all away because I felt I'd be wrong to give em to someone, well, someone I liked anyway. The K&N's were properly oiled and cared for, but still did'nt filter well. They have a place, but not (on my street machines. I have'nt put one on the Savage cause that durn filter does'nt seal well anyway. Last one I put in it, I used filter rim grease all over the foam to see if it helps. If it does'nt, I'll be changing to some other type of filter.
There is an interesting article somewhere on the Internet about air filters. It comparison tested various brands and showed the results. It concluded that the engineers who designed the engine know what the best air filter design is, for their engine. It said that an air filter has to be a compromise which allows sufficient air-flow, while still filtering the dirt out of the air. The tests showed that the K&N design did allow more air flow into the engine, but simultaneously allowed more dirt to pass through as well. It said that there is no mystery to making a K&N style air filter, and if the engine manufacturer thought this was the best design for the engine, it would have equipped the engine with that type. But the engineers also have to take into consideration engine reliability and a K&N type filter allows too much abrasive dirt into the engine to satisfy the engineers' requirements for long component life. ( It showed a comparison test of K&N against others, and showed the difference in particulate matter that passed through. K&N ( and foam filters) let more dirt through the filter than conventional designs.) The study went on to say that you cannot have both high flow and optimum particulate filtration simultaneously. It asked that don't you think that the manufacturer would have put that design (K&N or foam) filter on the engine, if it safely increased HP?
I suspect that the dirt some owners have found in the intake hose or carb mouth is the result of sloppy fit of the air filter in the airbox, due to poor quality control in the manufacturing of the airbox housing, and or from using a K&N or foam style filter.
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