Mod to the airbox.... has this been done?

Changing my filter and was wondering if anyone has cut the opening in the airbox to make installation and removal of the filter easier. Basically just trimming the opening so that it is the same size as the opening through the subframe. Would make getting the clean filter into the housing much easier. Thanks :cry:

It has never been much of a problem for me. :cry:

I figure for the MXers that would be fine. :cry: It is the trail riders I am worried about. Specifically, There is a lip that keeps water from just running in. When that is removed then there is nothing to re-route the water. Of course this lip is only about 3/32 of a inch high so it prolly doesn't do much anyway. Plus the side covers and seat protect from the direct water. I don't think there would be much of a problem...... just was curious whether others have done it. :cry:

Christien, the airboxes for both the WR and YZ are the same, thats why the opening is small and has inserts to secure a top lid.

My personal YZ426 has an airbox that is opened at the top, plus has been lightend by removing most of the airbox back wall and also cutting away the sides under the trim plates. Never had a problem.

I have taken real dusty times and stuffed a small chunk of foam at the front upper edge of the box by the tank, if it's wet you should use the oem optional deflecter at the tank/seat/airbox junction.

Done right this not only makes the filter change far easier, but also can change the airflow from under the seat/rear fender for a smoother flow which gains a little bit when getting on the throttle.

PK

PMK, the way you've modded your airbox sounds a lot like a stock YZ 2 stroke airbox. Have you seen one of those? :cry:

The '03 YZ airbox has a much larger opening in the top than the '01 does. I have often thought (whenever I wash the filters) about making my '01 250F airbox more like the '03. As Satch says, it isn't really a hassle to get the filter in or out, but you really can't put the newly oiled filter back in without dragging it across at least one surface of the airbox, as you can with the '03. Since the box isn't very clean, I worry about getting chunx-o-stuff on the inside edge of the sealing surface, so I make sure it rubs on the back side as it goes in. But then, if you don't clean it up, you end up with a bunch of crud stuck to the box where the filter oil got rubbed off on it. It's sort of a little thing, but the newer layout is a lot nicer to use.

I don't see a reason why it can't be opened up some, if you plan not to put a WR style lid on it in the future.

Chris

I might have seen the 2t, maybe :cry:, but common sense says the fender alone is a fine aft wall for the airbox, and the outer panels your boots destroy is a fine side wall. I chopped it for several reasons, access, saves weight for 0$, more common sense airflow to airbox.

The weight savings my not be huge, but I bet I removed 2/3's of the black plastic box and dropped it in the trash. Plush tossed like 6 steel screws.

PK

The '03 YZ airbox has a much larger opening in the top than the '01 does. I have often thought (whenever I wash the filters) about making my '01 250F airbox more like the '03. As Satch says, it isn't really a hassle to get the filter in or out, but you really can't put the newly oiled filter back in without dragging it across at least one surface of the airbox, as you can with the '03. Since the box isn't very clean, I worry about getting chunx-o-stuff on the inside edge of the sealing surface, so I make sure it rubs on the back side as it goes in. But then, if you don't clean it up, you end up with a bunch of crud stuck to the box where the filter oil got rubbed off on it. It's sort of a little thing, but the newer layout is a lot nicer to use.

I don't see a reason why it can't be opened up some, if you plan not to put a WR style lid on it in the future.

My thoughts exactly. After changing the filter the walls of the box are covered in goo. The next filter change I am going to open up the top. WTH :cry:

Chris

I might have seen the 2t, maybe :cry:, but common sense says the fender alone is a fine aft wall for the airbox, and the outer panels your boots destroy is a fine side wall. I chopped it for several reasons, access, saves weight for 0$, more common sense airflow to airbox.

The weight savings my not be huge, but I bet I removed 2/3's of the black plastic box and dropped it in the trash. Plush tossed like 6 steel screws.

PK

The reason I ask, is that the 2 stroke YZ250 airbox and sidecovers can be made to fit the 400/426 with minor mod's. The advantage of using the 2T parts are meant to be a small weight saving, and increased airflow. I'm liking your idea..... :cry: :cry:

Chris,

Long time back when I first saw photos of Everts 2001 works bike with the 2t airbox, I planned on doing the swap. Shortly after several guys here started talking it also. Sadly I couldn't find what I felt was a reasonably priced airbox on ebay to just experiment with, (at this point it hadn't yet been done) so I opted out.

One nice thing of the oem airbox, if anything complementary can be said of a boat anchor, is it does allow for hand holds. The other novelty is that until now, most folks had no idea the box is modified, it is totally stock appearing.

There are many ways to make the 426 better, and most remain hidden from sight or take a very trained eye.

PK

try removing the airscreen, and cutting the rear wall of the airbox down flush with the fender if you are lookiung for better airflow. You can also trim the handholds on the side panels so thay they dont force the air to turn a corner too.

PK, I actually went as far as buying the 2T stuff, probably 2 years ago now. After bolting it all up, I wasn't happy with the way it all fitted together, a few ugly gaps here and there, so I put it back to stock. I simply didn't have the time to fiddle with it, back then I was riding almost every day. A TT member, 'aremean troy', did an awesome job on his a while back, but he now has all 450 plastic fitted. I'll check out cutting the stock airbox during the week, cheers, Chris. :cry: :cry:

try removing the airscreen, and cutting the rear wall of the airbox down flush with the fender if you are lookiung for better airflow. You can also trim the handholds on the side panels so thay they dont force the air to turn a corner too.

What do you mean by cutting the rear wall flush? Got any pictures of it?

I dont have a before pic since all of our bikes are done this way. But it's the rear wall that runs up from the fender to the subframe. Think of it as the end wall in a shoebox. With it in place the air has to scramble over it and then down to the air filter. With out it, it's a straight shot at the filter. With that wall cut out and the screen tossed in the trash it will definitely breathe better.

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OK, I see now. Thanks. Pictures say more then a million words. :cry:

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