air box removal

hi i have a 08 wr250x and i was wondering if it would hurt performance or whatnot if i removed the airbox and put a cone airfilter directly onto the throttle body.

You got a fuel programmer?


I think somebody did this for a really bizarre street fighter conversion.

I'll have to dig around to find pics.

Yeah fuel programmer is needed with that. I'll see if I can find the pic; iirc it was a black one.

click me <-- dave _in_michigan at supermotojunkie

The black one that was REALLY freaky did not have airbox removed from what I found.

i dont understand why a fuel programmer would be needed for that modification. shouldnt the IAT sensor along with the ECU be able to compensate on its own?

You are TOTALLY changing the intake equation to a point that over-lean conditions COULD occur.

No real facts or evidence of this other than what I've heard and read for years.

The second you start changing the intake and exhaust you need to have the ability to add fuel to prevent over-lean conditions.

By completely removing airbox you are certainly making a drastic change.

If you have a stock exhaust you may be okay - but why open the intake so much if you have stock exhaust?

although your reply does make sense to me and i agree with it. although wouldnt this mod essencially be the same as removing the airbox door?

No.

Not in my opinion.

I also wouldn't suggest removing airbox door without a efi programmer as well.

Again - I've never once heard of a catastrophic engine failure on a 250x/r due to over-lean conditions.

Just going by what the masses report. which is this: "It's not recommended."


Are you willing to chance being the guinea pig for finding out where the limit is on "too lean"?


Do you have stock exhaust or not?
Obviously you don't have efi programmer.


What's your thought process on why you want to remove airbox completely?

What are you trying to achieve or gain?

hmmmm.. well ive been running with a K&N airfilter and the airbox door removed and the bike hasnt had any issues as far as performance goes.... none of the tell tale sines of running lean... i dont necessarily intend to completly remove the airbox, i just had the thought today while staring at the bike while it sits in my basement begging for some mods :P

Well, for starters a 250cc can only suck so much air at a time.
It can suck all that potential, efficiently or not.
One can open the air box fully...or even remove it. This engine will only suck, so much, from that hole,l where it is.
If a bike was modded to its full potential...removing the air box, or not, in the end...would be a minimal, if noticable effect...IMHO

If not a track/pro bike...I can not see the benefit....even if a pro.

...but that is just me...