CRF Air Scoop/Back Fire Screen/Air Box Mod

[Woody_393]

Here's my rendition of the above mentioned mods.

Air scoop mod (easiest )

Take the #er plates off the bike. and remove the scoops.

[Woody_393]

Now to the Backfire Screen (close second on ease)

I did all these mods when cleaning my filter so it would be easier since I'd have it all apart then anyway.

Once the filter is off bend the tabs off the filter cage, then you'll see some little tabs that hold the filter in around the edges, just wiggle her out. On the '04 models, the tabs I've circled don't exist so don't spend much time looking for it if you have an '04.

[Woody_393]

Ok, first off, no comments on what a mess my bike is... when I was all done I did clean all that crap up so it looks a lot better now.

I found that taking the rear fender off and going at this from the back side was the easiest. I also found that using a torch to heat up the blade I used to cut the plastic saved me a lot of time. it cut through the plastic like butter.

First take an un-heated (if you do in fact heat yours) and make lines where you want to cut. Then heat the blade and cut it off. If you don't use heat, simply go over and over the same cut spot until you've cut through it.

As you'll see it did a pretty clean job of cutting.




Notice my handy torch


From the back


From the side


Front view

[BigDad]

This is the best I've seen it explained. I can attest to the effectiveness of this mod. I did it a while back and there is a noticeable improvement in power. That's saying a lot, because I'm not that good of a rider and probably wouldn't notice insignificant gains. Very nice FREE gain in horse power.

[Woody_393]

Thanks BigDad, That was my aim... Hoping to make it easier for the next guy. Pretty easy mods to begin with, but still nice to have it laid out for you.

[VET393]

I did this same thing almost the same way. Great cheap mod I would say.

[smithers]

Id probably do all those mods except the air filter screen...Ive heard its not a good idea in case theres a backfire...havent seriously put thought to this yet or test fired my airfilter to see if it would explode.

[huffdaddy70]

Great write up Woody!

[Frakke]

Great write up Woody!! Did you change something to the jetting?

[strykmaster]

Wow Woody, that was a great write up. And to those who are afraid to remove the backfire screen.......don't be. It's not a problem. The only reason the manufacturers put them in there is because of liability. Not because there is a problem with these bikes backfiring. Honestly, has your CRF ever backfired? Mine hasn't. Remove it and gain a 30% increase in airflow. You're motor will love it. If you're nervous get a flame retardant air filter and use No-Toil.

[smithers]

I think I will do that this weekend...I need to get a new air filter also..mines not lookin so good around the wing-nut area. That was an excellent write up Woody...sorry forgot to tell ya that earlier.

[Mainjet2001]

Woody.......
You did an excellent job with the instructions and pictures.
Thank you.

Um...you could be our new ATM technical illustrator.

[Woody_393]

LOL, New Illustrator? Just doing what I can to help.

[MotoMojo17]

if you do that, just in case, you would want to think about one of those fire proof air filters...when you crank four strokes it is not uncommon to see them belch a flame or at least BOOM backfire

[Deano249f]

Can it be done on the CRF250R?

[Woody_393]

Don't know why not...

[Roostman]

Thats good stuff for you four strokers. And if your really worried about the firescreen, drill a bunch of 1/4 or 1/2" holes in it and youll at least have some protection and gain a descent amount of air flow. Just a thought.

[Woody_393]

Not a bad idea roostman.

[AndrewPA]

Woody, I am sure this is detailed somewhere but what were YOUR thoughts on the mod, did you notice the power gain or different characteristics. Also, any jetting changes?

Thanks

[Woody_393]

I thought it made a difference.

What it did, based off the seat of my pants, is made the bike a lot more ... hmmm... can't think of the word to describe it.. mean??? in the mid on up.