air box screen = more power

I have a 02 yz 426, I was wondering if I removed the screen on my air filter cage would it make any improvments. It seems to choke the airflow a little, are there any safty hazards on doing this. Any help would be apprecated. :)

02 426 mine lots of mods

02 tt-r 250 wife

02 kx 65 son ( until yamaha comes out with a yz 125 F)

82 ktm 250 sx restoring :D

If backfiring and catching your airfilter on fire, then no! :)

If you really want to do this get the Twin air backfire proof filter, you could cut out the screen but i think they make a kit for that with a screenless cage. Seems to me like some guys on here were saying that a yz250 cage will fit. Just make sure you get one of those filters so you don't burn your bike down, i've never seen it happen but you probably don't want to be the first.

Buy a YZ 250 cage (25 bucks I think) and make sure there is NO flammable solvent in your filter when you install it and you'll be fine. You can still wash your filter in kerosene or gas, but after you do that wash it in the sink with hot, soapy water and let it air dry for a few minutes (10-15) to make sure there is no flammable stuff in there. Lots of CRF guys have done this (their screen pops right out). If you don't believe me, ask therapture in the Honda forum :)

Just to add a little more info. I contacted No-Toil because I'd heard that their oil is not flamable (onc the alcohal evaporates). The gentleman there said that it is true that their oil is not flamable but that the filter foam certainly still is. He definately recommended not to do it.

I have a YZ250 Filter cage in one of my bikes and it didn't make any real difference. The only thing that it seemed to do was to clean up the jetting a little. It is such a small deal that I am going back to my original set-up. Both bikes, both with screens.

I used the "fireproof" Twin Air filters, and think that they may restrict the air flow that would be made up by using a sreenless cage.

That is my $.02 on that matter. I am going back to stock YZ450F cage with normal Twin Air filters.

Thanks for everyones input on the subject, I dont think I will be taking my screen off. The last thing I need is to become a flamming ball in the woods. :)

I tried out the flameproof filter and alternate cage yesterday at the track. I ran three motos with a standard Twin-Air then switched to the no screen setup for the fourth moto. The track I was riding on is a clay/lime mixture of some sort and is mostly as hard as concrete. With blue lines coming out of some of the corners. The change to the no screen setup was immediately noticeable. The bike simply reved faster than before and seemed to pull a little better on top. Overall the performance was reduced at this particular track because the faster reving engine cause more wheel spin out of the corners and made it tougher to maintain control on the slick stuff. I liked the original response much more for this track but might like the quicker response at the local sand tracks. It could be that I need to change the jetting to go screen-less but I didn’t get the feel that the bike was running lean other than how quickly it reved. It pulled as strong as ever.

I would really like to see a horsepower / torque curve done with and without the screens. Personally I didn’t get what I was looking for by removing the screen and will now look at spending money on a pipe.


I've used both No-Toil and the TwinAir anti-backfire filter without the screen and prefer the TwinAir setup. My bike definitly runs stronger without the screen. Just doing a visual comparison of the two filters, the TwinAir is physically smaller which they claim lets more unobstructed air in( on LH the side where the NoToil and stock filters almost contact the side of the airbox). The TwinAir foam seems to have larger cells than the others and lets more light in when held up to a light source. I would guess that would make it flow better than the others. The black anti-backfire foam on the inside does not appear to be any significant obstruction. :)

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