Best air box setup

[rgorm2500]

What are yor opinions on the best airbox setup. I am interested in the UM aluminum airbox with the 250R filter, I am not sure what brand filter i want to run with it, anyone have any ideas?
I really want it to breathe and take off when i open it up.:eek2: :eek2:

[cataway]

the best air box is no air box
http://i44.photobucket.com/albums/f9/cataway/8-11-2007LS008.jpg

[dylandrew1]

Did you have to adjust your carb after removing they airbox? I did a similar mod and it ran a little funny at startup (spit, sputtered and backfired a little). I plan to take it out tomorrow. Did yours run lean?

[cataway]

yes

if your carb is a stock setup and you remove the end cap from the muffler you should then change the main jet to a 142-145.
next thing is the pilot jet ,you may have to change that to ,going to a #25.
chances are the fuel screw will have to be adjusted ,it may be covered with a soft plug and have to be drilled to get to the screw

[dylandrew1]

Thank you. Do you have a detailed drawing of the carb? I may try to adjust it this weekend.

[cataway]

http://i44.photobucket.com/albums/f9/cataway/Carb_Labeled.jpg

[dylandrew1]

This is very nice. Thank you.

[fasterz69]

im running the pro design intake with an open airbox. i have a k&n filter with the outerwear and it is great. The nice thing about it is you can still hit water and mud without worrying about it going into your filter

[dylandrew1]

Oddly, in my experiment over the weekend with an open airbox, Pro Design intake, K&N, and Outerwears, I hit some water and killed it. After several attempts, I had to tow it back to camp (the first time it stalled, I was able to get it started again. The second time about an hour later wasn't so successful). After taking the filter and airboot off, it looks like water got in carb. Any suggestions? Do I need to take the Carb off? I guess since I planned to change the jets anyway, the timing is good :)

[jonboy]

I got the setup from JPMX to use the 400ex air boot and its large filter, I kept the airbox just to keep from getting mud,dirt ,and water into the carb and use an EHS airbox lid very effective and and stays pretty clean. It will also work with the FCR39 from the yfz450

NO the K&N will not keep all the water, mud and sand and dirt out. Even with the outerwears. If you are going to run in water or mud it is paramount to use at least some sort of splash shield if you get rid of the airbox.

[dylandrew1]

Understood. I'll modify a splash shield for the wet days. Thanks for the tip!

[dylandrew1]

OK. So I'm into the carb. The main jet is a 150-can't tell if is it Mikuni or Dyno. The pilot jet is a 60 and the needle is stock (I had a guy jet it when I bought the exhaust about two years ago, but didn't really know what he did). The plug is still in the fuel screw, so that was never adjusted. If the main is OK, could the needle diameter and/or position cause it to run lean? Or maybe the fuel screw position?

[cataway]

The pilot jet is a 60 ??? are you sure about that ? comes with a 22.5 ,most times it gets changed to a 25 and in some cases a 27.5.
seams to me the starter jet is a 60 leave that one alone.

drilling the plug out is easy but be very carefull ,it is thin and its the only way to adjust the fuel screw.

[airmobile101]

60 is your starter jet. Its the other two jets your after. Your pilot is the one that is inside the silver sleeve thats hidden in that pic thats posted.

[dylandrew1]

Understood. The other jet doesn't have a number on it. The other two have the numbers and then on the opposite side an "R" and what looks to be a square within a square. Any idea of what the blank jet is? Should I change it? What about the needle?

[dylandrew1]

All, I wanted to share the mods I made to the airbox. After removing the airbox completely, I got another one and modified it to work as a splash-box. Here's a few picks of the no-box:
http://i599.photobucket.com/albums/tt77/dylandrew1/noairbox2.jpg
http://i599.photobucket.com/albums/tt77/dylandrew1/noairbox4.jpg
http://i599.photobucket.com/albums/tt77/dylandrew1/Airboxtop.jpg
Here's some of the splash-box:
http://i599.photobucket.com/albums/tt77/dylandrew1/waterbox1.jpg
http://i599.photobucket.com/albums/tt77/dylandrew1/waterbox2.jpg
http://i599.photobucket.com/albums/tt77/dylandrew1/waterbox4.jpg
http://i599.photobucket.com/albums/tt77/dylandrew1/waterbox5.jpg
I haven't tried the splash-box yet, but hope to this weekend. Both are cheap alternatives to buying aftermarket or custom boxes. Hope these save you all a few bucks!

[dirtcrasher]

Big props to CATAWAY!! Great stuff for this forum

That was an awesome diagram to post up for this guy. Along with jetting recommendations etc etc.

Great help :cool: :D