[Logan]

Recently bought a trx400 and have a question about the air filter. The owner before me was running a K&N filter with the lid unmodified. After I purchased it I gave it a good cleaning but overall it was in very good condition. The air box container itself was awfully dirty so I gave it a good cleaning and put everything back together. Ive heard that the K&N's let small particles in and was wondering if I should switch to a UNI foam filter or something along those lines. I live in Wisconsin and the dust isn't terrible but there is some I suppose. Another thing, there's a plastic tube inside the air box that goes towards the front of the engine and I was wondering if it should have a filter or something on that also? Not entirely sure where it goes but I haven't looked into it to much. Any advice would be appreciated.

 

[Here 2 help]

The tube that goes toward the front of the machine is a snorkel that helps prevent water from getting into the air box - if you don't ride in water, you can safely eliminate it, but there is no need to.

Yes, K&N's let in more dirt than foam filters, but if you are racing and need that extra 1/10 HP at 9000 RPM's, then it might be a good thing. I race a motorcycle in hare scrambles and run the stock air filter in my 04 CRF250X - the engine has been rebuilt regularly as a normal maintenance procedure, but I am still using the original cylinder. Guys I race with using K&N filters have replaced their cylinders several times due to excessive wear. I keep a re-plated cylinder on hand so they (and I) don't have to wait for one when it is needed.

What part of WI are you in? My daughter lives near Madison. District 17 has one race scheduled at Adams, WI in Sept.

 

[Logan]

I'm in central wisconsin near eau claire. I have no intentions on racing I ride trails and woods. So I guess I'll invest in a foam filter. Thanks!