air box lid.

[fjyct]

i have an 06 400ex , and eveyrone i knbow keeps saying to take the airbox lid off. what is the point of this, is it a good idea, and will it cause any damage by riding without the lid?

[yellowzo3]

it lets the engine take in more air thus increasing performance. your filter will probably get dirtier faster if you do this so youll have to clean it more often

[RiderTRX400ex]

a lot of people do it to get better performance.. and when i finally took mine off wow what an easy upgrade.. it wont heurt anything as long as you jet it right, and yes your filter will get dirtier a lot quicker.. so clean it OFTEN

[250r4life]

yah, i would definately do it unless you ride in some extreme conditions (lots of water and mud, etc...).

if you're really worrried about it, get an airbox outerwear lid- they work great...

might wanna go a jet fatter on your main... should be fine without it though...

and ya'll should be cleaning your filter after every good day of riding anyhow...

[GPracer2500]

I wouldn't do it without changing the main jet--it only takes 5 minutes anyway. With the lid removed and proper jetting you'd probably pretty much have the midrange of the green line AND the topend of the blue line. It's all in the jetting...

http://www.geocities.com/gtthunder.geo/400stk2.jpg
(graph from GT Thunder (http://www.gtthunder.com/))

[boricua]

i hate to be the one guy who feels different, but.....i felt i lost a little on the bottom end. i guess being that there is less air speed, velocity, i lost torque (or better yet moved it up in the rpm range)......because its not sucking through the snorkle.....i have to pin it more often or rev it a bit more........
what ever i lost on the bottom, i gain at the upper mid to the top. for the riding i do, that didnt help me. i do run in those rpms but not often and even less do i maintain that range.
thats just me....and
my 2 pennies:)

[ELewandowski]

I never tried the no airbox thing, but i did take the airbox off completely and added a k&n air filter with an aluminium air filter brace. No box, it just supports the k&n and blocks the engine heat from the filter.

[atvn]

This was how I compromised between not wanting to run a lid but still opening things up a bit with out spending to much extra cash. It did change things enough to require a re-jet.

[YFZ450Ridr]

just take off the airbox lid and buy an outerwears cover. thier water resistant and work great. i have one on mine and my dads z400. i run harescrambles and thiers a lot of water/mud involved and i have had no problems yet.

as far as the power gains expect alot more throttle response, increase in bottom end, and a slightly faster revving engine. with the guy saying he lost bottom end, im willing to bet that the jetting wasnt right.

[ryanh250ex]

no lid does make for more power, but right now i'm not even running a airbox at all so :macho

[jsmith2232]

I didn't want to run with no lid at all i go thru alot of mud and water so i Opted for the k&n power lid and it definitely helped alot.

[rooster300ex]

If jetted right it makes a difference. Take your lid off, then get a outerwears pre filter to put on the outside of your filter to protect it alil more from water, and it keeps it from getting dirty as fast. for more protection you could get an outerwears airbox cover.

Magic Racing (outerwears airbox cover) (http://www.magicracing.com/Outerwear-Airbox-Covers_p_256-523.html)

[red2004 TRX450R]

Outerwear Airbox Covers work

they are water repellent not water proof
you should replace it ever 3-9 months because the water repellent wares off.

my 450r with a Outerwear Airbox Cover over the top of a home made HRC lid!!!

cant ever see the quad !!!!

[boricua]

Originally posted by LTZ400ridr
just take off the airbox lid and buy an outerwears cover. thier water resistant and work great. i have one on mine and my dads z400. i run harescrambles and thiers a lot of water/mud involved and i have had no problems yet.

as far as the power gains expect alot more throttle response, increase in bottom end, and a slightly faster revving engine. with the guy saying he lost bottom end, im willing to bet that the jetting wasnt right.

well, i checked my jetting and seemed to be good. i just lost a little air speed from not sucking through the snorkle. not everyones machine runs the same. would i agree that there is some power to gain from taking off the lid? yeah. i feel that most of the gains are in the upper half of the rpm range. i too run no lid. i just have to slip the clutch a bit or gas it harder.....

[bmurray]

heres mine, I made a few extra frames.

[Iliketogofast]

Originally posted by atvn
This was how I compromised between not wanting to run a lid but still opening things up a bit with out spending to much extra cash. It did change things enough to require a re-jet.

What did you use for the filter?

Okay, whichever one of you said taking the lid off lost some bottom end didn't rejet. You gotta rejet when you take the lid off or you're gonna lean out and loose power. Too many people see jetting as an option that will help out and isn't required: when you add more air, you aren't going to get any more power unless you add more fuel, and jetting is how you do that.

Also, I think a lot of people see it as being very hard, when there are only like 4 things to undo. On Honda quads all you have to do is undo the clamps that hold the carburetor on and flip it over, unscrew the hex cover on the bottom with a crescent wrench, and take the jet out with a 6mm socket wrench. Cake.

[boricua]

Originally posted by Iliketogofast
What did you use for the filter?

Okay, whichever one of you said taking the lid off lost some bottom end didn't rejet. You gotta rejet when you take the lid off or you're gonna lean out and loose power. Too many people see jetting as an option that will help out and isn't required: when you add more air, you aren't going to get any more power unless you add more fuel, and jetting is how you do that.

Also, I think a lot of people see it as being very hard, when there are only like 4 things to undo. On Honda quads all you have to do is undo the clamps that hold the carburetor on and flip it over, unscrew the hex cover on the bottom with a crescent wrench, and take the jet out with a 6mm socket wrench. Cake.

Thanks!:macho

While your post was/is informative, to some, I am no beginner and am familiar with jetting. My quad was rejetted, several times in fact. Ive made different lids with different styles and sizes and lengths of air inlets. Added a slip on. i have spent several hours riding without a lid, AFTER JETTING FOR THAT CHANGE, and felt a drop in torque in the lower rpms. after putting on one of my lids, and AGAIN REJETTING, torque was increased at the expense of some high rpm power. if you have a longer intake charge it will give you more bottom end, less top end....and vise-versa. the idea to get a happy medium of both.
I have no doubt you understand what im saying (maybe??)
but i know what im talking about, and again this is just my experience. in no way will i say taking the lid off is a bad or poor performance enhancement.....as long as YOU REJET!:rolleyes:

[jsmith2232]

That makes alot of sense, when i went to the 42mm 450 carb from the 38mm stock on my ex i felt as though my throttle "snap" had moved from the bottom to more into the mid range. So i guess that when you increase carb size it reduces velocity therefore pushing your peak throttle response into a higher rpm bracket. I know this has nothing to do with airbox lids but it would work the same way by taking the lid off and reducing velocity.

[rooster300ex]

Originally posted by bmurray
heres mine, I made a few extra frames.


I have a lid similar to that, and when i put it on there is a difference in the amount of air that i get because it messes my jetting up when i put it on.

[boricua]

as i said and many would agree.....opening up, removing or otherwise modifing your lid/air box will generally allow more air in through the filter. and thus gaining power.

jsmith2232, your right. using a bigger carb, usually will affect air flow through it. this is why many cylinder heads have more than 2 valves. ill try to explain: a 2" tube will allow a lot of air to pass thru it will low velocity/air speed. now take that same tube and reduce it to 1-1/4".....velocity has increased greatly but now the volume of air is low....not add another 1-1/4" tube. now you have 2 tubes, when combined is 2-1/2", and has a higher velocity and can flow a higher volume of air than the one 2" tube. The sizes here are just for describing purposes. so, 2 or 3 valves, though smaller than a single valve, combined flow more at a higher velocity.......

as soon as i learn how to post pic on here ill take some of one of my air box lids......