BannedCR500Riders.com

I know that there aren't many of us with this chassis but for what its worth. Recently I purchased a nice 03 CR125. My AF is also on an 03 CR125 chassis. The airbox on the new 125 had been modified with 5-1" diameter Unifilter airbox vents added and an 05-07 rubber boot between the airbox and carb. Doing a little research I learned that one of the worst design flaws of this bike is that it has tiny airbox intakes so teams were adding extra vents. I added 5 to the airbox of my 500 and took it out yesterday and wow, pretty big increase in power. I had to go up one size on the pilot immediately. haven't changed the rubber boot yet but I'm thinking about it. apparently the 05-07 boot has a less restrictive turn around the shock.

is it the same # as a 250 then?

125 and 250 boots have different part numbers.

hmmm.
the air filter thread i started before was to question partially the airbox aswell. at idle i can see the carb boot pulse with the gen 3 closed up like stock. havent tried it witout side plates or seat tho

Hey Adam,
I noticed my Gen 3 CRF450 airbox had been hacked up quite a bit for the 500. Its not pretty, but considering how open the gen1 airbox was i could see the need.

this is how my 125 was done, doesn't seem to be a problem as I ride in sand. not sure if it would be good for mud though. It also has all Cycra plastic and the Cycra rear fender is supposed to let more air into the box.

I have stainless steel screen and outerwares filter cover material on hand, just havent got the nerve to cut the airbox yet

got a full custom polished aluminium airbox for my 450 conversion to suit the 44mm am running and YES the bigger airbox is mint,def increase,even with the original 450 engine fitted they were choked up..

here is my first 500AF I built myself with modified airbox...

nice, i was thinking the same thing, but i'd use ourterwares over that to keep the water and dust out better

cool, yeah I think outwears was a very new product in 2005 when I built it.
Great idea though!

Thinking back to the first gen 3's I recall reading that Honda had updated and opened up the 450 airbox in 2005, for better flow, so it was already restrictive for the 450 I guess.