Air Filter Basics
                                                        

                                                  
You basically have 3 filter medias;

1. paper, (treated & untreated)

2. foam, (single or multiple density)

3. fiber, (manmade chemical or natural)

The basic untreated paper element is the worst out of all the 3 medias.  Our stock paper elements are basically just that. It is 'mildly' treated with just a light spraying ofoil and needs replacing most frequently.

The foam and treated fibers are the best for cleaning ability and longevity of filtration, in our RoadStars. The K&N's fall under the fiber class. 

The multi density foam filters would be right up there with their abilities of filtering and longevity, 'but', they require a little more maintenance than the man-made fiber types. Plus, their longevity may or may not be as good as the man-made fiber filters. Mainly because of their natural ways of 'breaking-down', over time. They also don't absorb heat and flame very well under a backfiring thru the carb.

An air filter article is really, another of those topics that takes a LOT of info to write, and it WILL generate a lot of diverse opinions which is best, .  

World of difference in ALL the different medias and what the air filters are utilized for, . Having an air filter designed for a multi-cylinder, high performance engine, and trying to use 'that' filter in a low compression, V-twin, like our R*'s, is just NOT going to work, . An air filter HAS to be designed for the application that it will be utilized in.

If I really had to write an indepth article of air filters and just our RoadStars , , I'd have to take at least a year off the Forum just for all the research and testing that needs to be done, LOL ! ! !

I wasn't fussing at you about the air filter article that you posted. Really.  Just wanted to make a comment that folks take an article like that with a grain of salt and just remember, we ride a low compression, low RPM, V-twin.

We've all seen the articles about Brand 'X' oil and how it's THE BEST, 'because', it was utilized in a fleet of 4 million 18 wheelers, that made non-stop convoy trips to Pluto and back, with only 1 oil change, etc., etc., etc., .  

Well, that's all well and good for the 18-wheelers, but folks want to say that Brand 'X' oil should be used in our RoadStars because of that 'fleet test' with a HIGH compression diesel motors, LOL ! ! !    WRONG, ! ! !   2 different worlds, (my opinion), .

Love reading the different articles of different products, when the test vehicle is a stock 2 cylinder V-twin, regardless if they're water cooled, air cooled, etc. At least the article is talking about a V-twin, LOL ! ! 
                      
Joel (Odo)