I have installed a K&N airfilter with an outer wear. i have been told that they were meant to be used WITH OUT my air box lid. i am not very fond of this idea. i do ride muddy trails but i "sally it" when i go through the mud so i dont get covered on my new toy. but anyways back to my predicament. do i have to rejet my carb if i drill holes in my air box? i already have had it re-jetted for my pipe and air filter. but should i get it re jetted again if i drill holes in my air box lid? i realize that if i dont like my results i will use duct tape to fix it... if you can duct it.... well you know the rest. thanks for any reply

 

u could get the uni air vents that pop into the lid, their cheap too

 

Do I have to rejet or not? drilling holes is FREE

 

Lid alone shouldn't be enough to need re-jetting. You could always carry your lid with you, and throw it on when you go through the really deep stuff. You shouldn't need it until it gets to about as high as a couple inches under the seat. The outerwears should deflect the minute amount that would splash up from 10-20 inch deep water.

 

I read something on a post in this forum that made a lot of sense but I don't remember who said it. Anyway this is the point. Removing an airbox lid or replacing a stock air filter with an aftermarket one serves one purpose: providing more air for the combutsion mixture. ANYTIME that this mixture is changed, the jetting should be changed to get the OPTIMUM results out of this mixture being burnt. The question that you know have to ask yourself is whether all of the work of re-jetting your carb is worth the extra performance that will be obtained by doing so. The amount of power gained from re-jetting is probably not very noticeable ,but just realize that "more" could be gotten out of your engine by re-jetting.

 

http://www.ehsracing.com/ Get an EHS racing lid. It has an Outerwears cover to keep the worst of the dirt out, yet it flows lots of air. Solves the holes vs open issue.

Just for the record, I have to say that I really distrust K&N's filters, even with an Outerwears. My suggestion is to stick with foam, like a UNI. The UNI for the 400EX is a nice, very large filter. It comes with a wire insert that replaces the restrictive stock one.

If you don't need to rejet, you have wasted your time and money!

 

You're getting some misleading information here. Do you know if you are running rich or lean with your current set-up? If you are running slightly rich you may not have to re-jet when you cut holes in the air box. If you are running slightly lean you will definately have to re-jet when you cut the holes. Obviously you know that by cutting holes in the air box you are letting more air into the motor. This will cause you to lean out your air/fuel mixture. A lean mixture can do serious damage to your motor.
If the quad is running good as is, you probably aren't going to gain much by cutting holes in the box. IMO.

 

it just depends on the size hole you drill into the lid.

 

figure out weather your running rich or not, then drill you some holes and slap in some super cheap external airbow filters for good measure. imo