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You must do this -

remove the mesh plate behind the airfilter....

drill 5-8 6cm holes in the air intake box....

less bogging - smoother acceleration and deceleration...

a bit more grunty

overall better ride..... simple and costs nothing....

it may be working better on mine as I replaced the stock exhaust as well - Ive done nothing to the computer or mixture..... Im going to expnad the whole to one inch and insert the filter plugs -

Now you have removed the mesh (Backfire screen) have you installed a low flamable filter and are using non petroleum based filter oil? I saw a Ducati burn to the ground once after removal of a screen, not pretty.
Think he saved half of the front wheel.

its a paper style filter - not a foam filter drenched in flammable oil - I think as long as not changing the standard filter - it will be ok.... http://crfsonly.com/forum/viewtopic.php ... 329e44ebbf - topic here

also - its not a carb engine - its fuel injected - so I dont see how its the same -

http://0.tqn.com/d/motorcycles/1/0/r/N/ ... way_lr.jpg - here is image - fuel injector is top right - air intake is right side - ..... this is cbr250

http://umarabuihsan.files.wordpress.com ... ensor2.jpg - reverse diagram

http://bikeadvice.s3.amazonaws.com/wp-c ... 250R-1.jpg - here you can see the full set up of the CBR - the backfire would have to come through the injection system - entire system - highly unlikely....

http://bikeglam.com/wp-content/uploads/ ... engine.jpg - this is the 250L

http://world.honda.com/CRF250L/engine/i ... htport.gif - Image from HONDA

http://www.cycleworld.com/wp-content/up ... t-port.jpg

A backfire would only have to come from the cylinder up the inlet port which is a pretty straight shot, and assuming the motor is running, the injector will ensure fuel is available to ignite.

The paper aircleaner should prevent the problem of having a foam filter with oil catching alight.

Yes injected bikes can still backfire.
road bikes have been injected for ages.

joevibe wrote:You must do this -

remove the mesh plate behind the airfilter....

drill 5-8 6cm holes in the air intake box....

less bogging - smoother acceleration and deceleration...

a bit more grunty

overall better ride..... simple and costs nothing....

it may be working better on mine as I replaced the stock exhaust as well - Ive done nothing to the computer or mixture..... Im going to expnad the whole to one inch and insert the filter plugs -

Are you replacing the mesh plate after the holes are drilled?

Can I buy you back fire screen
I bought my crf 450 on Sunday. By Monday it was on fire.

Toms_crf wrote:Can I buy you back fire screen
I bought my crf 450 on Sunday. By Monday it was on fire.

Ouch sorry man was it new?

Blow thru the filter, the backfire screen does not impede airflow at all.
I drilled all my holes up as high as possible to maintain the water tightness all aroung the filter box, not just the end cap. And the pugs really do nothing, thats why the filter is there!
But it does make it look cool, but added restriction!