Whats a good air filter for my 85 250R?

[AngusJustice]

I am running a stock air box with filter but I am considering putting a K&N filter on it and removing the box. Is there any reason why I should not do this? And what filters are you guys running on your machines and how do you like them? Thanks.

[Mr. Clean]

Most popular are the K&N or UNI. I have found that people feel the K&N flows too well and allows particulates thru the filter and run an outerwear. I used to run K&N's but have switched to UNI (no outerwear) and just maintain them regularly. I ride almost exclusively sand so every ride or every other I clean and re-oil.

A good test is to go and ride your favorite spot and at some point after some good riding and kicking up some dust, remove the filter and check the air box tube behind the filter for particulates. If there are any then you would certainly want to run an outerwear for maximum engine life.

And as Red Rider says below the choice of filter also requires you to consider if you are running a full airbox with lid.

[Red Rider]

All I've ever used is K&N filters, but I wouldn't run one without an airbox, especially if you're riding in any wet conditions. I run my K&N in a stock airbox with a ventilated lid. I tried using an Outerwear over the K&N, but it caused my bike to sputter & break up on top end, so no more Outerwear for me. Also, 90% of my riding is done in sand dunes. I hope this helps you out in your decision.

[RIDE-RED 250r]

Very much agree with Red Rider! Up here in norther NY, it often gets wet and muddy, so eliminating the airbox is out of the question for me.... Plus, about the only benefits to running airbox eliminator and centermount exhaust I have heard from trustworthy sources is a little better heat dissipation and possibly a gain of about 1hp depending on the engine setup...

I run my airbox with an un-altered lid, but I have removed the snorkel that connects the box to the mainframe under the tank. I still have adequate water protection for the kind of riding I do, (i wouldn't go pond crossing with it) and it flows really well. Had to step up 2 main jet sizes removing the snorkel. Oh, and I run a K@N with water resistant Outerwear. So far, no bad side effects...

[audioworks04]

I run a K&N and outerware on all of my bikes and have never had an issue. I 99% of the time I ride sand, I clean my filter and outerware after every trip. I have had people tell me to run a UNI, but ran it for one ride in the dunes and it was so filthy that I felt that it couldnt possibly flow correctly, and have since switched back to k&n and outerwares.

[Red Rider]

Allow me to clarify my statement about the Outerwear making my bike run like crap. My bike was jetted for a bare K&N, and ran great that way. I decided to try it with an Outerwear over the K&N, and it ran like crap. I probably just needed to re-jet for the Outerwear, but to me, that indicated the Outerwear was reducing airflow, which was the main reason I switched to K&N's in the first place.

[STiForester]

from experience, k&n will also lean out your motor a bit... i only run uni or stock if you can get your hands on one, but thats just my 2 cents

[zzmegad]

if its dirty and dusty use a foam filter(UNI) thats what i say,, yes they get dirty, you will get good at cleaning and oiling them. When I used to ride a lot I would have two filters that way I would have a clean one ready to go. I always use grease on the base of the filter to make a seal and the spray on oil makes things a little easier i think. When they get dirty I clean them in a bowl with gas then rinse with the hose. I like K&N, I have them on my street bikes and stuff, but I feel for offroad you should use a foam filter. keep them clean and oiled

in all fairness i have never tried an outerwear, I imagine that makes a k&n a lot better in the dust

[Gripit'n'ripit]

I run a UNI with an air box. I've taken it all over NY and to the sand in OK. The air box doesn't seem to restrict air flow, and it mostly protects the filter from water and large debris. Currently working on a 2nd gen 250r that my buddy took mudding with an uncovered air box and a UNI. Ridiculous amount of mud and debris just sitting in the box, but the UNI seems to have done a good job.