Opening up Your air box.

[Spyke]

The question i have for all the off roaders is how do you open up an air box without making the airbox pointless of having because it doesnt stop any the shit getting to the filter??? I have a ts185 i'm doin up and would like to free her up a little, i could use a poddy but that would be impractical because i'd have to clean it every ride. Any ideas folks?

[Macstar]

Dirt was not a concern when I drilled holes in my KTM motard air box - man did it make a difference BTW!

I was told however that you can buy an adhesive, waterproof yet breathable film by a KTM mechanic. Sorry can't give you more details than that as I didn't pay much attention at the time. There is a product out there though!

[Str8 Jacket]

careful, airboxes can be tricky.
I wouldn't reccomend doing anything irreversable unless you have a spare.

[Spyke]

I've got two to play with, lol what could go wrong?

[98tls]

Squeeze what you will into it but unless you do something at the other end

[cheese]

I saw a trick that was all the rage a while back.

Use a 40mm hole saw and cut two holes either side of teh air box. Then put mesh behind it and rivet it into place through the side of the airbox.

Looked pretty cool, not too sure if I'd bother though.

[koba]

careful, airboxes can be tricky.
I wouldn't reccomend doing anything irreversable unless you have a spare.

Opps, wrong user ID! that was meant to be me saying that.
Fucking about with the airbox could make it run like shit basically.
Do some reading on it, modern ones are a fascinating science plus a bit of background knowledge could give you idea of where to start.
Generally it is not a case of letting more air in but more of using pulse effects to "supercharge" your engine in the disired manner.

Read.
Have a go, could be a real good experiment.
Let us know what you do and what effect it has.

[Henk]

I've cut away most of the airbox lid on a KDX. Small performance gain but mainly to use more of the filter. The stock box and snorkel funnel the air through the same 2 square inch chunk of filter. Having said that this is one of the well documented mods to the trusty ol KDX. Your mileage may vary.

[Spyke]

Squeeze what you will into it but unless you do something at the other end

That isn't to hard on the old ts, it's got a slip on muffler held on by a bit of rubber. i'm making a strait through muffler at school at the moment, real good experience.

i'll read up more on it before i try it, i've got the filter and oil now all i have to do is do it.

[Spyke]

I've cut away most of the airbox lid on a KDX. Small performance gain but mainly to use more of the filter. The stock box and snorkel funnel the air through the same 2 square inch chunk of filter. Having said that this is one of the well documented mods to the trusty ol KDX. Your mileage may vary.

I noticed that too on the old filter one part is really dirty. Which part of the box would be the best to cut so theres less dirt exposure?

[F5 Dave]

As high as possible. On my old KDX some turkey had drilled holes in the side. Which meant it was as waterproof as a a Morris Minor going over stream crossings. Obviously this doesn't worry a Motard.

I will mention that given the decent intake & the correct jetting there will be no improvement from extra holes. If extra holes make an improvement it will be as the jetting was too rich from std (often the case for safety) &/or the intake noise is noticeably increased. You can get to the point where there is no more restriction to the power from varying intake size but more will require richer jetting for no benefit in power. Henk's point about more filter area on a dirt bike is valid though.

Holes make pretty crappy intakes btw. Flat sharp edges (with no smoothing ie: drilled in an airbox side) flow badly compared to rounded intakes. However these can be over restrictive to meet noise stds. Many bikes lose power if the intake trumpets are merely just removed.

On old bikes (like TS I'd imagine) the airboxes are so small they are restrictive.

[Spyke]

Ok I've done a little bit of research on the air boxes and generally what I've taken in from some of the other sites is to basically take the snorkle out and cut a bigger hole if needed.

I was thinking of a hole saw for the job? and then filing the edges.

for some of the newer dirt bikes they say just to leave the top lid off, then do a couple of slight adjustments.

and does anyone know the best way of sealing the airbox lid. mines on the side and that could lead to drowning the bike quikly in the river.

OH and i read something about pressure waves in the carb, if i make it breath more will it tamper with them?

[crazyxr250rider]

All road legal bikes(or bikes meant for it in other countries) are over resrticted
in the intake to meet noise restrictions just cut the lid out.
I got a big bore high comp. piston kit for My '91 XR250 opened the exhuast and air box (chopped whole top off) and it goes at like hell now beats mates KLX with ease...

[CRF119]

My first MX bike was a 1990 XR200 motor in a RM125 Frame. Went well. The top of the air box had a rubber intake wich wasnt overly big. I got one off a 400 and cut the box to suit. had to make the bike alot richer to compensate for the extra air. Also found the bigger exust system helped was about 5-10mm bigger header and muffler then std. Of course to put more in it still has to get out.