I have a 1998 400 scrambler, 4x4. THe air box is broken. What are the suggestions on completely taking the air box out an installing a Straight filter. If so What would I jet the carb out to. This quad is new to me I would like to do things right, but get the most out of it I can. Faster for the money if possible without compromising the 4 wheeler.

 

The air box is used for a water tight seal in most cases. I assume you mean a K&N filter ..........Not K&M.
Is your quad running a pre-filter now?
Will there be enough protection with the stright filter for your riding conditions?
Example...Sandy, dusty,dirt roads at higher speeds.....etc,,,,.
I for one would rather the most protection rather then the most I can get out of it!
Just my point of view though........Caper......

 

If you're not gonna be dunking it like a donut at the local precinct, you might try a k&N filter (with prefilter) and a k&n airbox lid.

I would not get rid of the airbox. Like Caper said, it's there for protection too. Imagine going through the woods and having a stick stab the filter. Could leave a hole, could tear it completely off.

 

There is a post on the first page now of a stick going through a gas tank on a Polaris Sportsman 450..........Yes a Gas tank....He should buy a lotto ticket......LOL............Caper...........

 

Had a nice sized one come up through the nerfs on my kfx. Darn glad I was wearing my alpinestars.

 

That all makes alot of sense. I Like what You all posted. Part of the reason I posted this is when I bot this the inner filter frame on this air box is broken out. So I guess I am looking for a new Idea. Thankyou Madvmax

 

If your Scrambler is still all stock you might not make anymore power with the clamp-on filter.Back when I first started working on my Sport 400 I didn't find the factory airbox to really be that restrictive with the basic bolt on mods like a pipe, silencer and matching clutch work.It wasn't until I switched to a bigger carb that the factory airbox became a restriction and at that point all I did was take the top off of it.

With a high compression head, extensive port work with a matching pipe and a fairly big carb (something like a 42mm) then the factory airbox might might actually become a restriction.I've never tried the factory airbox on my Sport 400 with this setup because to be honest with you it just takes up too much space under my seat and I need that room for my nitrous solenoids, fuel pump and wiring.

If you do go with a clamp-on filter then I would suggest bracing your carb with something to keep it from jiggling around so much and having fuel flow out of the vent tubes so much at idle because of the vibration of the motor.