K&N filters seem to be great. They allow more air in for more power. That's why alot of car racers use them. But on the other hand, cars usually don't go mud riding and kicking up roosts in the dirt and sand. I think it all depends on what type of riding you do. Uni might be great for engine protection from the dirt, but doesn't allow enough air to gain more hp like the K&N filters and vice versa. I don't ride dunes, or deserts. I mainly ride grass and trails (not mud). I sometimes do MX riding to at the local track. I think I like the K&N.

 

It all depeds on your riding conditions. Like me I sand drag, ride in mostly sand and dirt. I run a K&N with no air box or prefilter. Like i said i clean it about evey month. I take it off and look inside the boot just to see if there is and dust or anything inside it by whiping my finger back up in it, NEVER EVER HAD ANY KIND OF SUBSTANCE ON MY FINGER YET.

Now when your talking about a UNI there thick 2 layerd foam, its harder for air to travel threw them and then for that air to reach the carb. yes they do stop more dirt from entering but to me K&N is just as good stoping dirt and dust as UNI. I would lose valuable HP if i went to a UNI and all i do is sit at the drag strip all day and i want as much HP as i can get

 

if you have an airbox get a kn and put an outerwear on it. I run dual kn's on my banshee and they work great

 

The power difference between a K&N and a UNI isn't really that big, its not like your going to lose 10HP here, your not gonna lose 5 and your not even gonna lose 2.. I would be suprised to see a 1HP loss. I don't know about everyone else but I'm not going to risk dirt getting into my engine over a half a d@mn HP. I've seen K&N's let dirt through more than once. My cousin is running twin UNI's on his SixSixT intake on his Raptor and those things flow a rediculous amount of air. We ride some EXTREMELY dusty and dirty conditions and they provide superb protection. I run foam filters and thats it. Run a K&N if you want, it will bite you in the @ss eventually.

 

All those people saying they see K&N letting in so much dirt. I've run one on my forman for 7 years with no troubles. I keep mine maintained and clean and its in an airbox. I wouldnt run one outside an air box because you'd have to clean it too often (plus I run deep water with a snorkel so I have to have an airbox.)

If these filters let in so much dirt, then there's something wrong. Either they heated the wet filter while drying and shrunk the cotton, dried it with pressurized air and disturbed the cotton element, or it got damaged from being exposed to the elements.

 

I have used a k&n on my machine for about 5 years. Never had a problem.

I have used UNI filters on previous machines... also no problems.

Always follow the directions for cleaning and maintaining per the manufacturer.

 

About 7-8 years here. 3 machines with K&N. No problems.

 

I ran a K&N on my warrior for the last 7 years and cleaned it like 3 times. the dirtier your K&N the better the filtration. you dont need to clean them all the time. if you see a white spot from the water washing the oil off squirt some more oil on it. that warrior was ridden at least a tank of gas everyday for the first 4 years of its life. If i wasnt riding it my buddy was. When i pulled the cylinder to rebuild. It was still like new. Valves looked new. Amsoil in the motor and K&N on the intake. ridden in Dusty clay powder to sloppy mud. asd anything inbetween and outside.

 

Actually u do lose HP. I watched the guys at the dyno run a 300ex stock witch was 16Hp then they ran a K&N, it pulled 19HP thats with being rejetted. They ran the UNI with it being getted up still it pulled 17Hp. They then jetted back to stock and run the UNI it stayed at the Stock HP (16HP). They ran the K&N with the 300 at stock jetting it pulled 18HP, the operator of the dyno said this was because the K&N is giving more air flow to the carb but not enough gas with the stock jetting. I watched this because i was tring to decide if i wanted to go with a UNI or K&N when i first got my Drag Bike. Would never run a UNI

 

I would have to see the sheets to believe that one. The fact that some of you say that you wouldn't run your K&N without the airbox means something to me, I'll run my UNI in any condition and never be worried. BTW, got any pics of that YFZ??