When I got my bike I figured I'd be doing mostly off road. Then I got it and road about 90% road, if not more. So I got a K&N because of that. And when I did go offroad I'm not riding with people that kick up dust so I figured I'm good. And I also of course kept the airbox lid on with the snorkel removed.

Anyway, fast forward. This year I did mostly offroad instead of road riding. But still, I'm not riding in dusty conditions. As in riding behind people kicking up dust. And most of the time,being it rained all year, it was wet. But apparently, that doesnt matter. If the ground is even dry, what little dust kicks up off the front tire will get sucked into the box........cuz thats what happened to me.

And for the first time in my life.....that I can recall...There was dirt inside the air boot. Now, I know K&Ns dont filter as well as foam, but all the years I've been off road I've seen people with them all the time, even with no airbox at all. Now I know its not the best, but I still figured ti worked..........it doesn't.

Maybe I left it go too long between cleanings. Maybe I didnt get a good seal. The damn fins on the air filter were bent a little. It BARELY fits in the airbox, and its near impossible to get that metal cover over it in the back. It probably bent some. However, I remember feeling around the bottom with my fingers and I thought I felt it seal, but then that plastic lip covers it a bit some too.....so..........I dont know. I also don't know how much dirt got in either. I always smear oil inside the boot, just in case some does get it. And there was a little bit of dirty laying at the bottom, and a tiny tiny bit on the airboot walls. So, its not enough to make me take it off, I'll keep an eye on it. If it does it again, its gone.

I could pass the same amount..........probably more I'm sure, of air by putting a foam back on and taking the lid off. Or I was thinking of cutting the back of the lid off, where the hole for the air snorkel is. That way, if I want to put it back on, I can fit it up like a two piece. That should increase airflow. I'll probably pick up a twin air though, those UNI's are trash. I always hated that two piece system. You never know if its lined up right. And sure enough, the inner filter doesnt fit properly over the cage. Its like these companies don't even test their products. I'm not putting the stock sponge back on, It filters well, but it should be replaced. I just keep it for emergencies. So....I guess Twin Air it is if this doesn't work out.

 

I am not doubting your results or circumstance, and I've read this type of report many times about K&N's...but...in many years of running K&N's on dirt bikes, I honestly have never experienced this issue. I raced enduros from the mid 70's into the 90's. All my dirt riding now is strictly recreational. When I started racing various 4-strokes in the mid-80's, I started using K&N's. Anyone who's raced enduros knows how dusty some of them can get depending on rider numbers and soil condition. I've been in some enduros so dusty that I've seen a rider have to remove his foam filter, squeeze out the dirt with some gas from his bike, and continue with an unoiled filter just to keep going. Any K&N that I had never plugged up this badly, though it did look like a chocolate cake at the end of the race. And doing bike maintenance after the race never showed any noticeable buildup of dust in the clean side of the airbox, airboot, or carb. Frankly I was amazed.

Yes...I hear these horror stories quite a bit on forums, so where there's smoke I"m sure there must be some fire...or dust...LOL! I have no stake in K&N stock or a reason to promote them. I'm just honestly saying I've never seen this oft mentioned issue through many years and models of bikes running the filter off road. Frankly, servicing a K&N is a bit of a pain IMO over a foam filter, so it's not even from an ease of service issue for me. I'm not dissin' anyone's circumstances on this issue, so don't take this wrong.

 

Couple filter facts.

1. The more dirty it is the better it Filters....ie effeciency goes up.
2. The more dirty it is the harder is is to get air thru it....ie bigger pressure drop.

Those two statments never change with any particulate filter...ever.

Sounds like you didn't get that k&n filter seated good in the airbox and it was getting bypassed.

FYI ..... I would say the exact same thing for any brand air filter. Physics is Physics.

 

ive seen the flow carts for k&n vs foam, seen the pictures of up close (spacing for air/dust to move), and have used both. i only use k&n on cars, foam for bikes. k&n lets a lot of dirt threw, it actually filters better dirty cus of this, but k&n probally makes more power, and my single cam honda needs all the help it can get. the foam filters 10x better, and with a single cylinder to mess up, thats what matters to me on my bike. i have also experinced the "i ride alone 99% of the time, how is my filter so dirty" situation, the thing got caked bad.

 

Yeah I dont know what to think, thats why I'm giving it a second chance. I just bought a new bright flashlight and one of those telscoping mirror things over at Harbor Freight so I can get a good look in the box when I put it back in.

 

I have never had any problems with k&n filters and have been using them for 20 some years. One thing to remember is always use grease on the sealing services. It's a biach to get them in but after a few times it gets alot easier.

 

Jason,

I've had a k&n in my klx since 06. Most of my 11k+ miles are in dusty azzz sugar......and riding with my fast friends and me on the only dual sport, I get a lot of roosting and never mind the dust from playing sweeper. I usually got a bandana over my face.

Never had visible dust, downstream of the filter, except the first cleaning, which I did back in 06 after first ride with it. I could see it was not seated right, letting sand bypass.

I use marine axel grease to seat it now......it's a bitch to get in there right, but once its in there and seated right, its fine. If not for the lifetime warranty on the sucker, I'd be tempted to just put in a foam filter on da klx.

 

Finger Mullet touches on an important issue. I always dab a tiny bit of grease on the rubber that seats the K&N into the OEM airbox. Some foam filters recommend the same thing...or at least used to back when I used them. It's amazing how dirt can squeeze through the seal of a filter and the housing, and on a rubber based K&N it's even easier without some grease IMO. I notice Kawasaki even has a recessed rubber seal on the backside of that removable filter mount in the OEM KLX box...the one you pull to cut out the backfire screen. That shows how critical that area is for sealing against dirt.

Here's an interesting circumstance that I observed some years ago. I worked part time at a motorcycle shop to pay for my habit. Three of us in the shop all had '86 XR250's that we raced every enduro on our state's circuit..."B" long course class. At the end of the year, my XR was the only one that didn't require a piston and rings. I went nearly half way into the next season before needing a piston and rings. The other two guys weren't goobers who didn't maintain their bikes. They used Honda OEM foam air filters, and I used a K&N. They frequently kidded me about using an old "rag" filter...referring to the fabric based design. One of those guys was the one who had to wring out his foam filter with gas during a particularly dusty enduro because it nearly shut the motor down. What does this prove?...nothing conclusively. But it was pretty clear that the K&N didn't kill my engine at the very least. I've experienced the same thing on every bike I've owned that ran a K&N. I've seen some fairly hot-and-heavy debates over the K&N vs. foam issue, but I guess I've been lucky or blessed to have excellent service and results on my bikes. Anyone with the least concern about it should just run one of the many fine foam filters out there and worry about other things.

 

Foam all the way. Too easy to carry a pre oiled spare in a zip lock bag for those longer ADV rides and swap it on the go. K&N is goo for the slab.

 

duhhhhhhhhhh, grease? I thought that seal said for oil or grease? I had plenty of sticky air filter oil around there....apparently thats the problem?