250x airbox mod

With the airbox top cut out, my filter seemed to accumulate quite a bit of dirt. I just glued a square piece of window screen over the hole I cut. Has anyone tried this? Do you think there is a negative effect to this? I know there may be a little bit of air restriction, but is there anything I should worry about with the screen?


Try stretching a "Filter Skin" over the hole after putting some oil on it. That way you're not just creating a seive for the small dirt to get through. or maybe a little oil on the screen...er but then again maybe oil the sides of the airbox. I did this on my blue 02 400 and in the so cal desert and sand, it worked great and the clean up was a better deal than cr** in the carb.

I have not mod my box on the new X. Post if you're successful in making it better than what you got now.

PS how did you break in. Hard or by manual specs?

Air filters are supposed to accumulate a lot of dirt. This also means you are accumulating a lot of air. The surface area of an air filter is large enough to accomodate a certain amount of dirt buildup and still provide sufficient air flow. A filter skin pre filter isnt a bad idea but it will slightly reduce airflow. Pre filters are designed for air filters that are more exposed to the elements to keep large debris from sticking, clogging, and possibly damaging the element. As far as screening over the air opening, I say why. You shouldnt be getting any large debris in the airbox under normal conditions. What you are seeing on your filter is a build up of fine dirt that sticks to the oil (thus the design) . Todays filters are designed to let air pass through the foam causing it to change directions slightly causing airborn solids to adhere to the oil via surface tension. Any single layer pre filter, or screen that was fine enough to keep this micro fine dirt out of the air filter would also be keeping too much air out. When riding in central ca summer a filter looks dirty after one hour. After 3 two hour rides (in the summer) I will clean the filter, but cant honestly say that I can see a performance difference, thus maybe the filter isnt really as dirty as it looks! M in M

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now

  • Similar Content

    • By Connor Wright
      Hey I have a crf250x 2005 I was riding today in top gear flat out and when I slowed down blue smoke just poured out the exsaughst then I happened to open the air box lid and saw it has what looked like engine oil in it then took out air filter and noticed that there was splatters of engine oil on the inside and that and the channel that goes to the carby had engine oil all over it.
      Also bike got a top end rebuild 15 hours ago
      The engine still runs good and sounds normal
      why would this be happening on a resonabley fresh engine
    • By mikemcbride
      Hey everybody. Quick question for y'all. I recently went riding and about halfway through my ride my motor seized on my '07 CRF250X. I haven't investigated it much but I checked the oil when I got home and there basically was none so I'm assuming that was the culprit. There weren't any metal shavings in the filter or on the plug either. At this point I'm trying to decide to rebuild the motor or just sell the bike as is and let the next buyer deal with it (they would know the deal obviously.) I feel that I'm pretty mechanically inclined but rebuilding a CRF engine is a bit out of my league and I assume paying a shop to do it would put me out more money than the bike is worth. So, I have this question to ask; what would be a fair price for a pretty dang nice shape 07 CRF250X, with a seized motor with an unknown extent of internal damage?
    • By ThomasM.
      selling Hot Cams Valve Shim Kit that i bought for my 2005 crf250x, will also fit crf250r.
      used 1x 1.30 and 2x 1.55 shims. the rest is still there.
      $60usd shipped in the usa or canada
      please contact me for pictures or if you are not sure if it will fit your bike
    • By TerryA
      I have two rides in on my new Rekluse auto clutch and I have to say I'm very pleased. The install wasn't hard, but was pretty much a all afternoon sort of project. I also installed a left hand rear brake kit and a two finger cluth over-ride with the adjuster on the perch (which I rarely seem to need). It has all worked great right from the beginning. After struggling to get up a tricky hill in first gear, I tried it in second and the autoclutch helped me clean the hill easily. Not having to worry about clutch action in techinical sessions has also eased fatigue and just made it more fun all the way around. I ride mountain bikes alot, and having both brakes up on the bars has also been nice as it makes for a set-up just like the bicycle - in fact I like that as much as not having to worry about clutch manipulation. The brake on the bar is especially nice on tricky downhill sections where you need to paddle, such as nasty rock/rut stuff. So first impressions are that it was worth the investment -making the ride more enjoyable and easier at the same time!
    • By Mikey560
      I was driving the bike for 15min or so and all of the sudden the bike stalled. I tried starting it again with no luck. I took the spark plug out to see if there is spark so i ground the spark plug to the frame and there is no spark. I even put a new spark plug in the bike and still nothing. Any ideas what i should check??