open air box good or bad?

[honda 400ex 69]

i just put in a jet kit and got the t -4 pipe so i figuered i would run it with out the air box lid. is this bad cause my dad wasnt to big on it and by the way i put panty hoes over it to block dirt
works good

[Teufel]

The Delima here is to get asmuch air flow as possible with out letting dirt and water in. Riding in the water and mudwith he lid off is a definite NO. The panty hose and or outerware is a step in the right direction. Clean that filter often.

[RAPTORAZ]

The only downside to an open airbox is that you'll have to clean your filter more often. Make sure that you also keep the air filter well oiled. I've been running without the airbox lid on my EX and my Raptor for years. However I don't encounter much mud or water out here in the desert.

[86atc250r]

We've found that in many cases, on a 400EX you'll actually lose a bit of top end with the airbox lid completely removed.

You also have to be very careful about not getting any water or mud spashed onto the filter or you'll be well on your way to an engine rebuild. Certainly not worth the risk if you ask me if you ride in an environment with either.

So what is a person to do? Vent the lid. Vent it behind the filter with a 2 or 3" hole, preferably with something like a speaker box port to keep any water or mud splash from being able to directly contact the filter. Run with the airbox drain plug removed or modified (to make sort of a one way valve), so that any water that enters the box will drain by itself.

We did numerous timed runs on two different quads (one stock and one modified) and found that the vented setup was consistanly faster than either a completely closed lid or a completely open lid, even after making jetting changes.

[yamaha1470]

Originally posted by 86atc250r
We've found that in many cases, on a 400EX you'll actually lose a bit of top end with the airbox lid completely removed.

You also have to be very careful about not getting any water or mud spashed onto the filter or you'll be well on your way to an engine rebuild. Certainly not worth the risk if you ask me if you ride in an environment with either.

So what is a person to do? Vent the lid. Vent it behind the filter with a 2 or 3" hole, preferably with something like a speaker box port to keep any water or mud splash from being able to directly contact the filter. Run with the airbox drain plug removed or modified (to make sort of a one way valve), so that any water that enters the box will drain by itself.

We did numerous timed runs on two different quads (one stock and one modified) and found that the vented setup was consistanly faster than either a completely closed lid or a completely open lid, even after making jetting changes.


Is that totally open with no prefilter or outerwears?
Right now I have the lid with a huge hole in it with the prefilter and the outerwears attached to the lid. Should that be good?

Thanks

[86atc250r]

That was with the stock filter and a completely removed lid.

My guess is it had something to do with airbox volume. You'll notice on almost all late model cars that particular attention is paid to the volume of the intake tract.

We found the best results with around a 2.5" to 3" hole in ours, for our setup. Others may differ, depending on your particular setup.

Get a couple spare lids (they're VERY cheap from servicehonda) and do some testing to see what works best for you. The most important thing is to protect the filter.

Here's a pic (http://home.earthlink.net/~gellett/airbox_mods.htm) of what I ended up with, it's kinda dirty and the pic is a still from a webcam, so the quality is poor, but you can get the idea..... Notice how the vent protects the filter.

[honda 400ex 69]

dude i never go in deep water and the dirt and dust stays out pretty good with the panty hoes is this good

ne ways if u get water in the box isnt it in the exaust too the top of the box is high and a lil splashes will run down to the plug which i check often never has ne thing

[86atc250r]

You don't have to submerge the bike to get water and mud splashed into the open airbox.

I'd not be too concerned about water entering the exhaust, however, it is a big problem if you get it on the filter.

Take my word for it now, or learn yourself - your call.....

I run with no lid and an aluminum airbox. add some foam strips to your plastic, it will block the "splash" water and mud from getting into the box. you can see the gray strips here in this pic.

[racin 400]

hey fastnfurios.How much would u charge for a sub frame like yours.:confused: