i am thinking of a 440 kit, any suggestions?problems?durability?

 

ya 440 kits are nice bro...fmf or whitebrothers...ive heard nuffin but good things bout umm but if u dont wanna spend that much first drop a k&n air filter in it and take off ur air box..then buy a jet kit of e bay or from a shop then put a pipe on it not big gun tho becuase they dyno it at .4 less hp then stock go with a whitebrothers type r or a supertrap or something...my friends has that exact config and beats the other 400s by bout 2 bike lengths up the hills

 

Can anyone explain why taking the airbox lid off would give it more power? I have heard this many times and am wondering.

 

HondaGuy300EX, With the Air box lid on it starves the motor for Air at high RPM's. I run a 2.5" hole for most riding and remove it on Race day...

 

If you ride in water, do not take your air box lid off. Can get very expensive.

 

i already have k&n,pro-circuit pipe,jet kit.i dont have a problem with low end power,just the middle to top.on a large jump,sometimes i need more power just before the take off,can't always get another gear on a tight moto-x track.just wanted to get the skinny on a 440 kit,thanx.

 

Consider a cam before the 440 kit.