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View Full Version : YFZ 450 air intake mod.



quadboy-55
08-27-2009, 01:21 AM
heres an intake mod i did recently to my 07 YFZ. it noticably incresed airflow, and is fairly easy to do. it took about an hour and all you need is:

-10ml socket and socket wrench
-Screw driver (+ for removing clamps)
-Dremel with a disk cutter
-Glue gun
-paper towel
-Sharpie or other permanent marker.
-common sence and a set of basic knowedge to get the job done right (LOL)

1. start by removing the seat and the four 10ml bolts holding the air box on. loosten the engine breather from the airbox. loosten the clamp on the intake hose to the airbox. now compleatly remove the airbox.

2. remove the stock air box lid and place it to the side. remove the airfilter and place it in a **clean** low traffic area

quadboy-55
08-27-2009, 01:22 AM
3. remove the stock rubber end from the top of the airbox lid, you will need it for later so hang onto it.

quadboy-55
08-27-2009, 01:26 AM
4. using the rubber piece, on the back side of the airbox (filter outlet being on the opposite side of you) use the rubber end piece and outline the thin side onto the right side of the part that sticks out. then repeat this step with the airbox lid inlet on the same spot. now you should have two outlines of the same 4 sided shape, one inside the other. refer to the pic below.

quadboy-55
08-27-2009, 01:27 AM
without the rubber end piece in the way you can get a better understanding of step 4.

quadboy-55
08-27-2009, 01:29 AM
5. use the dremel to cut inbetween, but closer to the inner line. the outer line represents the airea you do not want to go past.

heres after what youre cut should look like.

quadboy-55
08-27-2009, 01:31 AM
6. the rubber piece will not yet fit in here yet, so continue fine tuning the cut, by expanding outwards untill you achieve a perfect fit for the rubber end piece.

here is the finnished cut.

quadboy-55
08-27-2009, 01:35 AM
7. hot glue the perimeter of the end piece and place it inside the airbox like this. then glue the edges of the rubber end piece so it remains in the box for a long time.

quadboy-55
08-27-2009, 01:40 AM
8. for those of you who want to still use youre airbox lid you will find that it blocks just over 50% of youre new hole. what can you do? this! start by installing yorue lid, and through the hole outline the new hole onto the snorkel piece of youre airbox lid like this with a permanent marker.

quadboy-55
08-27-2009, 01:41 AM
when you trim the air box lid snorkel it should look like this.

quadboy-55
08-27-2009, 01:44 AM
9. when you place youre air box back onto youre quad you will find a number of things. one of them being that a plastic wall is covering 70% of that new hole and that there is no place for it to breathe fresh air. fear not, the next few steps show you how to trim youre plastics for optimal airflow to youre new air inlet.

quadboy-55
08-27-2009, 01:50 AM
10. with the airbox back in the quad, but not bolted yet, its time to pull out that sharpie again, and outline (again) on the plastic the same shape of the fresh cut piece. this will open things up a bit again, and move that piece out of the way, but still act as a snorkel to keep unwanted water and track dust out.

quadboy-55
08-27-2009, 02:06 AM
11. with that area cut out, solves one dellemma, but brings up a new one, where does the air come fromm? at the bottom of the plastic you will find youre answer. by shining a light from the top casts a shadow you can see from the bottom, trace this with the sharpie about 1/8th of an incha back, to leave room for error. once you have drawn the triangle, cut it out, and fine trim untill it sits flush with all three sides of the triangle.

it should look like this.

quadboy-55
08-27-2009, 02:11 AM
12. now, re-install the airbox in reverse order from wich you removed it, making sure all bolts and clamps are tight. but no overly tight. when properly installed the new airbox inlet should sit flush with the cut out area in the plastic that leads to the opening. and the new hole should sit close to the airbox lid hole with kindof a little fin for the air to go both ways.

when you fire it up you should be able to feel it sucking from the triangular hole when you rev the ATV.

here are some aditional pics.

quadboy-55
08-27-2009, 02:13 AM
*note, some jetting changes are nessesary after the install of this mod, as it allows noticably more air causing a lean mix.

mxpimp2000
08-27-2009, 08:32 AM
nice write up quadboy, now just cut that screen outta the intake and optomize ur flow:D

quadboy-55
08-27-2009, 12:22 PM
yea, i was thinking about doing that untill i can get an FCI.

justin1022
08-28-2009, 12:14 AM
nice mod weres that rubberfrom

quadboy-55
08-28-2009, 01:39 AM
used to be on the airbox lid.

racer 557
08-29-2009, 04:15 PM
justin it even says in the article take rubber off of air lid it will be used later

quadboy-55
08-30-2009, 12:29 AM
Originally posted by racer 557
justin it even says in the article take rubber off of air lid it will be used later

LOL, thanks bro.

quadracer55
09-27-2009, 11:16 AM
looks nice, what made you think of this :rolleyes:

quadboy-55
09-27-2009, 07:10 PM
MXpimp2000 did a similar mod on his YFZ.

mxpimp2000
09-27-2009, 09:12 PM
Originally posted by quadboy-55
MXpimp2000 did a similar mod on his YFZ.

:D

kyledvor61
10-01-2009, 07:00 PM
Also, you can drill holes in the airbox lid, or take the lid off.

quadboy-55
10-07-2009, 10:51 PM
Originally posted by kyledvor61
Also, you can drill holes in the airbox lid, or take the lid off.

my set-up is running with the lid off. the problem you encounter with no lid is the seat sits really close to the airbox anyway that you "really" dont gain that much performance out of it.

mods like mine, and mxpimp's gather extra air from a custom drilled out hole elsewhere in the airbox with its own intake hole.

heres an interesting fact i encountered to prove the capacity of this mod. after it was all done: if you place your hand by the hole in the rear plastic where it draws its air under the quad, you can feel it suck noticable ammounts of air, and thats with the airbox lid off aswell.

pondy
12-04-2009, 04:01 PM
im going to do this mod but am going to do it to the other side as i dont like the idea of it being next to the exhaust as it can suck in hot air, the coolant rezzy will give some protection to as i race mx but can get wet and muddy
sam

mxpimp2000
12-04-2009, 04:04 PM
Originally posted by pondy
im going to do this mod but am going to do it to the other side as i dont like the idea of it being next to the exhaust as it can suck in hot air, the coolant rezzy will give some protection to as i race mx but can get wet and muddy
sam

i decided to just get a FCI intake and ditch the box all together. also went to a uni foam instead of a K&N. i race mx and as long as i got a spare filter i should be good to go also kept my stock box incase i do get into a wet condition i can slap it on and be ready to go b4 race time more air = more power

quadboy-55
12-04-2009, 07:38 PM
Originally posted by pondy
im going to do this mod but am going to do it to the other side as i dont like the idea of it being next to the exhaust as it can suck in hot air, the coolant rezzy will give some protection to as i race mx but can get wet and muddy
sam

nice. the only reason i took the exhaust side over the other side was becasue the airbox lid rubber grommet would leave i nice (VERY CLEAN) matching factory look. becasue that side is the same shape as the airbox lid intake. good luck with performing your mod!

i also cant wait to get one of those HEP battery boxes so i can cut the plastic around it and that leaves way more room and a more open space for my new inlet to draw more air sooner.

pondy
12-06-2009, 07:29 AM
i dont want to remove the air box completly due to muddy conditions we can get, im in the uk so an fci is out of the question, im running a stock air box with the pro design k&n set up with lid off, you are right the seat almost acts like an air box lid and i didnt really with about it untill i saw your post

im getting back on the dyno in the new year as have changed exhaust, last dyno numbers was kinda low so with new pipe and this mod hoping to see a good increase. i have been thinking and will be doing this to the coolant bottle side, but may also do somthing on the other side also, when washing the bike i will have to remove the filter and bung the hole up

i have also cut all the plastic out from around the battery box
sam

quadboy-55
12-06-2009, 01:46 PM
Originally posted by pondy
i dont want to remove the air box completly due to muddy conditions we can get, im in the uk so an fci is out of the question, im running a stock air box with the pro design k&n set up with lid off, you are right the seat almost acts like an air box lid and i didnt really with about it untill i saw your post

im getting back on the dyno in the new year as have changed exhaust, last dyno numbers was kinda low so with new pipe and this mod hoping to see a good increase. i have been thinking and will be doing this to the coolant bottle side, but may also do somthing on the other side also, when washing the bike i will have to remove the filter and bung the hole up

i have also cut all the plastic out from around the battery box
sam

sweet. i hope you enjoy you mod you are about to do. and just for the record. i dont believe how many people i have to tell this to, but an FCI WILL WORK WITH YOUR STOCK AIRBOX! its just a new tube and an adaptor that mounts to your box.

pondy
12-08-2009, 03:16 PM
yes i heard that the fci does work with the stock air box, i think alot of people cut the back of the air box off to make the filter easier to fit and remove. its not really an option for me to import an fci, would be to much and take a while to get it here

today i cut both the holes out fit the rubber parts, just waiting on another air box to get the part off. should make a good increase in power, thanks for posting this
sam

mxpimp2000
12-08-2009, 03:36 PM
you can cut the rear out of your box and leave the rear fenders housing stock because it covers up around the sides of the air box which will block alot of water id say 80%. with just this mod done you wont be able to feel the gains but u will gain some air flow. to actually feel a HP gain youd have to actually get rid of the airbox and stock intake its self

heres a link to something neat i found but it wouldnt be something i would use im about saving weight and making every hp possible

http://images.google.com/imgres?imgurl=http://www.blingracing.com/images/YFZ450-Undertail-no%2520tails.jpg&imgrefurl=http://www.blingracing.com/yamaha%2520YFZ450%2520Undertail-no%2520tails.htm&usg=__rDHAkpPA9OE0gNou603U5oZuyys=&h=221&w=311&sz=45&hl=en&start=13&um=1&tbnid=mUdIspEhn_reLM:&tbnh=83&tbnw=117&prev=/images%3Fq%3Dyfz450%2Bair%2Bbox%26hl%3Den%26um%3D1

mxpimp2000
12-08-2009, 03:42 PM
this is a pic of what it would look like if u cut ur rear box out. you will still have the protection of the plastic guarding ur filter

http://i121.photobucket.com/albums/o224/mxpimp2000/yamaha4.jpg

pondy
12-08-2009, 03:53 PM
thanks for the pic, i have already cut out the plastic around the back of the air box as i run a aftermarket battery box
sam

quadboy-55
12-10-2009, 06:10 PM
overall, i think the new tube with the FCI is much more worth it.

and no problem, im glad my write up helped you out Pondy.

and the FCI filter is the same sise as the Prodesign K&N, or the Sparks foam filters. so really theres no hassle in removing it.

mxpimp2000
12-10-2009, 06:15 PM
you can buy parts of the fci you dont have to buy the kit. theres a fci vendor on yfztech forums that can sale you watever parts it is that you need. but if u just want the tube u gotta have the transition ring and boot to run it. here is what garret quoted me

"If you just want the tube its 120 and the adpater is 20 with hose clamps, transiton ring is 45. It would be 180 plus shipping"

quadboy-55
12-11-2009, 07:26 PM
be better to go with my route then. TQS, 169 shipped, sell the K&N privatly, buy a foam with the money you get giving someone else a replacement FCI filter.

that way you get everything MXpimp2000 said, + a Foam filter of your choice, and a 'lil change left over to go buy a donut, LOL.