drilling holes in the airbox lid?

[chargercalvin]

a previous owner drilled some big holes in the airbox lid on my 300ex. it has a k&n air filter. would it run better if i covered up the holes or should i leave them?

-calvin

[chevys&honda$]

is it jetted?

[chargercalvin]

i dont know for sure. it probably has a jet kit. it has an fmf megamax pipe, 14tooth up front& k&n filter. i would think a jet kit would have been done also. does that matter?

[DEVINF450R]

If you ride in any dusty or sandy conditions I would ditch the K&N

[HCRacing]

Originally posted by DEVINF450R
If you ride in any dusty or sandy conditions I would ditch the K&N

Why would you want to ditch the best air filter in the world. just get a pre filter for it. I have run trails and hills of sand and everone i know uses K&N.. I don't think this guy know's what he's talking about..

[DEVINF450R]

I dont know a single person that uses K&N Air filters that I race with... Know a few guys who run a FUEL Intake and use an 8-ply cloth filter and had good luck. K&N are 4ply and suck. Why do you think every dealership sells them??? so they can get paid to put new rings in your quad:D

[JParisi48]

the holes r fine, leave it, but get a prefilter and your all set, ull get a wee bit more power with the holes drilled out, i had the same setup on my old 300....

[Scro]

As long as you are jetted to compensate for the increase in airflow, you should be good to go. Does it backfire when you let off the throttle, fall on it's face at a certain RPM, or hard to start? These are some of the things that may happen if it's not jetted correctly.

Definately get a pre-filter for your K&N. Or better yet, buy a UNI filter and prefilter, and have the peace of mind that no mud or dust is getting past it:macho

[Tommy Warren]

If the guy you bought the bike off of knows anything he would have jetted the bike when he put the exhaust and air filter on. K&N makes a powerlid but i've only seen it for 450r's and 400ex's if you go to their website you might find one for the 300ex of maybe the 400ex's air box lid is the same as a 300ex i don't know for sure does anybody know? here is what a powerlid looks like.

[631kfx400]

K&N just isnt good. i run a UNI in my dads 400 and its a great filter. some people say cutting holes in the airbox lid lets more air to travel into the airbox for more power. i personaly think it is Bull Shyt

[Scro]

Originally posted by 631kfx400
i personaly think it is Bull Shyt

It's not, as long as you rejet. More air + more fuel = more power.

[Tommy Warren]

i agree it's gotta give you a little more performance getting it straight from the lid rather than sucking air through the frame like these 300exs. what a stupid design

[MTDman11]

Originally posted by Tommy Warren
i agree it's gotta give you a little more performance getting it straight from the lid rather than sucking air through the frame like these 300exs. what a stupid design

stupid design? any woods rider would love this! you can ride in maddd deep water on a stock sport quad! it is actually a genious design. a racer can simply pop off the lid while a mudd bogger would need a snorkel.

[Tommy Warren]

Originally posted by MTDman11
stupid design? any woods rider would love this! you can ride in maddd deep water on a stock sport quad! it is actually a genious design. a racer can simply pop off the lid while a mudd bogger would need a snorkel.

I see what your saying but I don't know where the air gets into the frame. If it comes from a low spot in the frame you could just suck water through the frame. I don't know where the air comes in therefore I don't know how deep I can go. My buddy's 450r has a stock snorkel that comes out of the air box lid and up to the front of the seat, he knows how deep he can go. I'm always worried about that when i get into water.

[MTDman11]

it comes in right near the handle bars. way up there! i have gone thru water that is just below the seat and no problems. just a little water may seep into the airbox cause the caps arent always water right.

[trey porter]

what size UNI filter should i run in my kfx 450r

[chargercalvin]

cool ok i will do prefilter and rejet

[justin1022]

k&n just let more dirt by i run no air box at all and have a sock but i clean it like once every couple tanks of gas.

[MnBluePits]

Originally posted by MTDman11
it comes in right near the handle bars. way up there! i have gone thru water that is just below the seat and no problems. just a little water may seep into the airbox cause the caps arent always water right. Im guessing here u dont have a stock air box cause i look at mine and there is a drain hole on the bottom and with the air being sucked then wouldnt that suck in water too? and thats about mid bike i would say ??

[Tommy Warren]

Originally posted by MnBluePits
Im guessing here u dont have a stock air box cause i look at mine and there is a drain hole on the bottom and with the air being sucked then wouldnt that suck in water too? and thats about mid bike i would say ??

if you take your filter off you'll see where the hole is in the bottom of the airbox. It has a cover over the hole to stop water from coming in but you can take it off and let water out.

[MnBluePits]

mine just has a hole with a tube no cover should i have one?