I don't see how anyone knows how these filters are sealing once installed without using a bore-scope type inspection camera. It's the face that makes the critical seal & no one can see it once in place. If these replacement filters have a slightly different OD or the rubber/foam frame has a different thickness or it is not as pliable - you're likely to have a gap once installed. As pointed out already there's no flange for the top side of the filter to press against inside the air box, this is the area that's most vulnerable to leak. If nothing else you pioneers will want to check for dust getting around these filters after dirt rides - please let the rest of us know how it goes. ------------------------------------------------------- On the subject of improving the airbox & without looking in it again, I'm wondering if it's possible or practical to... 1) Cut off the plastic frame that the filter sits in & throw it away, keeping only the plastic panel as a cover plate. 2) Make & install a top face flange (that's currently non-existing), maybe use small, like 1/16" thick, aluminum angle. 3) Make & install back flanges. 4) Slide the filter in place between the flanges, now we can visually ensure a snug fit before installing the cover plate.
FWIW, the frame that the filter sits in is screwed to the cover plate, so it doesn't even need to be cut off, just unscrewed. You can even save it and if not happy with R&D, put it back to stock.
I'm reviving this thread since Am.E and HighFive have put their heads together on an airbox solution. For those who aren't following, they used a 3d printer to create a solution for the stock airbox, thus eliminating the need for the pod mod. So that being said, they used the stock filter size. I think both used the Uni AU1016, however any stock size filter should work. Is the K&N our only option other than the Uni? Does anyone have any other suggestions?
Hold a K&N filter up to the light and see all the big holes that provide the increased flow. Don't you think dirt can get through those holes also?
Are you asking me? If so, mail me a K&N filter and I'll test it as directed. I've honestly never used one.
I use to race off road and always used a K&N filter, but I always used a pre filter. When the filter would get clogged we would yank the pre filter off and stick a new oiled pre filter on. I always carried two pre filters in the truck and had one at every pit. I never had dirt in the carb. The pre filters always did a great job with the filter always looked brand new when I removed a pre filter.
I'm not mailing you anything. Use whatever filter you like, however, it's been proven over and over that K&N filters are nothing but BS hype and have been responsible for "dusting" numerous engines. Do a google search on "dusting, K&N, Powerstroke" and you will get an education.
I wondered when this thread was going to go this way. Go ahead and read the tests, but think about the validity of the testing methods, and their relevance to the application. Also remember that Can-am motorcycles came with K&N's from the factory. The 82 and 77 I just sold were still on their original 40 year old filters, and standard bores. If the filters were not up to the task, I'm sure we would have heard about it by now. Oiled foam, or oiled cotton. Choose your poison, but next time you're looking at your foam filter, note that it's more holes than foam.
Alleged elimination of the pod mod. The pod mod is the best solution PERIOD for cleaning the air into the engine.
Watch the video and decide for yourself about what filter to use. Feel free to discuss the validity of this test. This is a basic controlled environment test, and the results are definitive. And... Dyno tests are somewhere here on CH.
Re: K&N FWIW. Some years ago a construction company did a comparison of K&N's with the stock paper filters on their heavy equipment, including dump trucks. They found accelerated wear in all that were using the K&N's. The oil analysis showed higher levels of silica as well. I quit using them after reading that evaluation. However, the use of a pre-filter would probably reduce the possibility of contamination. Me, I'll stick with oiled foam like I use on my dirt bikes.
All filters have holes. It's the depth of the media combined with the size of the holes that filter out the unwanted particles. With small holes, you can get by with thinner media (think pleated paper filters). With bigger holes, you need depth to create a convoluted path that causes the particles to "hit a wall" and be trapped in the oil as they are exposed to multiple turns in the path through the media. Foam filters have big holes and depth. K&N filters just have big holes.
And after some fair amount of use I can confirm that the filter still perfectly fit and did not warp, unlike the Unifilter. Also the sealing grease is still working like a charm.
