04' airbox mod

I was wondernig how to do the airbox mod, i found the air filter but i dont know what to remove.If anyone has pics please post them thanks.

Start by taking off the opposite side cover, and cutting out the 2 pre-molded 'punchouts'. I haven't learned yet to harness all the power the WR has after that, plus the grey wire, YZ-stop and PMB/or GYT-R exhaust insert, but you can get more radical. Maybe Indy's Airbox Mod and/or the YZ exhaust cam? Can find both by Searching.


Check this link for photo's under "make it run right" it might give you an idea what to look for. :)


the airbox mod in the link above isn't the same as the pre-indented cut outs on the RH side of the 2004.

i don't know if the 03 and 04 air box are the same....are they?

The airbox was updated for '04. Not sure if you could retrofit one or not.


yes and no. the '03 doesn't have the premolded areas on the side of the air box. we have rivets holding the black cover in place instead of screws. go easy on cutting big holes in the sides of you airbox. if you ride around much water it may not be your best option. first off make sure you have removed the snorkel from the standard air intake. if you see two holes that are about one inch square, it's still there. if there is just one hole with a single "web" in the middle, then it's out. to remove it you have to use a screw driver to help it over the little metal clip. cut out the indented area on the left side number plate to match the right. change the pilot jet to a 48 and start there. your still going to have to play with the needle or replace it with a j.d.

what is the snorkel?where is it?how do i take it out?I dont really understand your directions could you post a picture and give me step by step directions.Thanks :)

i haven't figured out how to post pictures yet but i think i can walk you through it. on top of the air box you have the air intake that is behind the battery area. in yamaha's effort to make the bike quiet, there is a baffle of sorts in that intake opening of the air box. it should be removed. if the dealer has not removed it it will appear that there are two holes for the air to go in. each hole will be about one inch square with about one inch between them. if you grab the lip of one of the holes the insert will move a bit. if you try to pull it out it will hit the battery strap clip. take your battery out. you can then use a screw driver to "help" it past the clip. if the insert has been removed there will appear to be just one hole. in the middle of that hole will be a single narrow cross piece that is only to give a little strength to the air box top since it holds the battery. hope that helps.

ok i got it out thanks for the info, i had to work at it though


the Canadian 04 450 air box doesn't have a removable lid or any kind of intake boot. just a big rectangular hole. and the indented cut outs on the side.

i cut mine out and re jetted my bike today. bike is really coming to life now.

Do you fellas really need this power? More power=less engine life! I tunned up my old wr426f 2002 and in the end my tranny died. I'm not going to do the same with my 2004. The bike has so much power stock! It is true I did some head mods that made 4hp on the real wheel (http://www.mototuneusa.com)

Thanks for the guidance on removing the air intake baffle. I ended up cutting the baffle in half with a screw driver and hammer. Then pushing each half down into the airbox and out the side cover opening. I thought I might break the battery tray if I pryed the baffle out the top. It was difficult. Two mods down (exhaust and intake), and two mods (gray wire, and throttle stop) to go. :)

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