screenless cage

17 replies to this topic
  • ncmountainman

Posted March 31, 2005 - 07:03 AM


well i decided to try to save a little money. instead of buying the twin air cage & filter for $100. i found that the same year yzf parts work on the wr intake. although i run a yzf airbox already this will work on the wr box also(as its still the same intake shared by both bikes) i had to order the fire resistant twinair(yz450f) and then the yz 250 2-stroke filter cage, wing bolt,& washer(don't skimp on the washer its a special one) then the cage reciever from yzf (the part that attaches to the intake) all this totaled less than $70. now i know people say " no more HP on the dyno" when removing the screen. BUT,this swap also lets alot more airflow just because of the design(the wr stuff is much more restrictive) ok well now you all say well your gonna lose bottom end! well,yes and no. i've done so much to enhance the bottom that the addition of the boyesen ap cover about made it too much. now the power comes in right off idle but is a much smoother power that builds evenly to a (now unbelievable) mid and top. this power delivery is awesome for the tight woods i ride. i call it luggable screamability :naughty: ...... now that i think about it , if i would've bought the twin air cage it just would have been for the wr reciever and i would not have gotten as much airflow;just no screen !

  • Dan_Lorenze

Posted April 01, 2005 - 08:23 AM


Nice report and mod... :naughty:

  • ncmountainman

Posted April 01, 2005 - 01:12 PM


i just ordered the yzf 450 filter cage (it has a screen) just to see if it might move a little more power to the bottom. it was only $13 ,so if it finds a happy medium between what i had(stock wr) and the wide open yz250 cage it'll be perfect. i kinda like the idea of a screen anyhow. and i'll still have gained flow because the yzf setup has about 15% more opening. the filter is the same for the yzf450 and the yz250 so thats not an issue. i knew you could easily move power around with the exhaust,but never realized how easy it is to do on the intake side :naughty: will let ya know which cage works better on thurs. :naughty:

  • kirkw

Posted April 01, 2005 - 03:01 PM


Thanks NCMM, I always appreciate your experiences you report.

  • beezer

Posted April 01, 2005 - 05:43 PM


I think you can open up a WR airbox pretty easily. The 05's make it easy with no drilling rivets and cutouts on the side. The lefthand sidecover has an opening that the earlier bikes don't

And of course the snorkle pop out easily.

The side panel cutouts for earlier bikes can be found in 250 FAQ section.

  • ncmountainman

Posted April 02, 2005 - 06:16 AM


i'm not talking about opening the box, i'm working with the actual intake end. the wr has alot more restriction after the filter than the yz's do :naughty:

  • beezer

Posted April 02, 2005 - 11:38 AM


But 99% of us are going to use the stock WR airbox.

The debate is still open about eliminating the backfire screen.

I have heard that many Supermoto teams still use them.

I have tried it on other bikes and didn't notice a difference but I'm a yardape not a professional tuner.

I have my WR going fast enough for me, I just wish the rain would stop so I could ride it.

  • beezer

Posted April 02, 2005 - 01:00 PM


I was fooling around in the garage with an 05 YZF250 and I noticed there was no screen in the filter cage so maybe there is something to be gained by the screen removal.

My 05 WR has the screen but not the YZF250.

Its the first 4 stroke I have seen come without it.

  • ncmountainman

Posted April 02, 2005 - 01:25 PM


i think the biggest gain is from the improved flow of the larger hole and more filter surface of the yzf450. the cage and reciever bolt right up to the stock wr intake and box. the seal is alot better with the wingnut also. as i said i'm gonna try it with the screened cage also(yzf450) any way you look at it this mod gives you a whole new mid and top. i'm running a 170 main and usually drop down to 168 for summer,but won't have to now! :naughty: MO powa MO betta

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  • luke_n

Posted April 02, 2005 - 06:40 PM


So with the standard WR airbox you order...
The YZF receiver.
The YZF 450 filter cage. (with the screen)
The bolt and the washer.
So the YZF receiver has the threads for the bolt to screw into and hold the filter on. I have been thinking of going to this style setup since I bought the bike, just doesn't seem very secure with the strap.

At the forefront as always Mountainman,


  • Indy_WR450

Posted April 02, 2005 - 07:37 PM


Great idea to test both. Let us know what you find out with the differences. Thanks NCMM :naughty:

  • xcracer123

Posted April 02, 2005 - 07:50 PM


I have cut the screen out of every filter cage or airbox on all the 4 strokes that I have owned with no problems. I always just figured that it restricted too much airflow when my goal was to increase said airflow. I have not experienced any problems thus far in doing this. It was done on a '97 XR400, '02 DRZ400 and now on my '04 WR450. Figured it was cheaper than buying that $100 Twin Air mod.

  • ncmountainman

Posted April 03, 2005 - 02:28 PM


So with the standard WR airbox you order...
The YZF receiver.
The YZF 450 filter cage. (with the screen)
The bolt and the washer.
So the YZF receiver has the threads for the bolt to screw into and hold the filter on. I have been thinking of going to this style setup since I bought the bike, just doesn't seem very secure with the strap.

At the forefront as always Mountainman,


don't forget the yzf filter,make sure you order the same year parts

  • ncmountainman

Posted April 07, 2005 - 10:14 AM


ok , i threw in the screened yzf450 cage today and ran it through the same paces with my SOP dyno (seat of pants) accurate to within 1/10 hp :D. results were exactly as i suspected,it smoothed the transition from bottom to mid but did not lose any percievable top end. damn near perfect power delivery :naughty: so for anyone wanting to do this mod just get all yzf450 parts from the same year(i know it works on 03-04,everyone else is gonna have to do their own R&D) intake reciever,filter cage,bolt,washer,and filter. all yzf450 yielded the best results. and yes it is a big improvement over the WR setup. i'm gonna check battery box clearnce on indy_wr450's bike this wknd just to be sure. i'm fairly confident it fits. will report back mon. :naughty:

  • Ga426owner

Posted April 07, 2005 - 11:06 AM


I would suggest purchasing TwinAir's - flame retardant air filter if you are going to do this mod....unless you like to worry about the filter catching fire from a has happened :naughty:

  • ncmountainman

Posted April 07, 2005 - 02:51 PM


ya somewhere back i mentioned it just forgot to include that in the rest,its only $8 more than the regular one. but i think you'll find i also mentioned better power delivery with the screened yz450 cage.

  • wr450oregon

Posted April 07, 2005 - 04:03 PM


ncmm I'm a bit confused (nothing new) while Looking on bike bandit for parts are you talking about the yz450f or the yfz450 ATV. You have yzf which is a 4 cylinder street bike :naughty: ?

  • ncmountainman

Posted April 07, 2005 - 07:05 PM


i guess properly it would be yz450f ? any how after looking again at my old parts this whole thing might not work unless there is about 1/2" of air space below the battery tray for the taller filter assembly. i can't remember and i don't have the old air box. anyone care to measure the stock ones clearance? the yz450 setup needs a 1/2" more headroom. it works in mine because i've changed out the airbox and no longer have a battery. i hope it fits the stock box as this really added some giddyup :naughty: if it does fit theres another issue of where the extra air would come from on the stock box (its kinda restrictive) so i guess if it fits one would have to open up some more flow somehow. man,this is getting complicated. well for all those people with 03-04's who have removed their starter and battery,its quite simple; order the yz450 airbox $50, a yz450 cage reciever $23, a yz450 filter cage w/screen $13 (it actually runs better with the screened one) ,wing bolt and washer $6, and regular twinair filter for yz450 $24. and if the stuff does fit under the battery then its also worth tryin'.....i didn't figure things gettin' so complicated :naughty:


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