Interesting Air Box mod idea, need input

7 replies to this topic
  • armourbl

Posted March 31, 2002 - 06:21 PM


Here is the thread I posted...


  • Guest_Guest_*

Posted March 31, 2002 - 09:33 PM


1. You are going to get EXACTLY the SAME amount of air going into the carb because it ALL still has to come thru the top of the airbox.
2. If you take the filter off of the original place it is designed to fit and seal off the debris from getting into the carb and put it on the top of the airbox, you are allowing stuff to get in thru the bottom of the airbox.(I believe there is a hole somewhere in the botto with a hose on it to allow escape of foreign debris such as oil and water.) Take a look!
Just my $.03

  • armourbl

Posted April 01, 2002 - 07:05 AM


On the WR model that hole in the bottom is plugged with a closed clear hose and must be removed to allow the box to drain if needed. Unless you are doing lots of water crossings, there really isn't much need to have that hole open.

The larger space in the air box should allow the air to travel into the carb more freely. The air will still have to pass the filter, so yes some restriction will still be there.

Only real problem I see with this is there will be less surface area of filter, so it will most likely get dirtier faster.


  • Shawn_Mc

Posted April 01, 2002 - 08:40 AM


The major problem with what you want to do is, the exposed area of the filter isnt large enough to pass enough air for the engine at operating RPM. The size of the filter in the air box really doesnt matter until the filter becomes clogged. The top of the air box isnt large enough to accomodate a filter with enough area to flow enough air, unless you were dealing with street ridden application. As an example, look at the shear size of the airfilters on an offroad racing truck. Massive is the word your looking for. If it was practical, a filter that was twice as big as the factory unit would be preffered on the YZF's.

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  • armourbl

Posted April 01, 2002 - 11:51 AM


I'm loving the valid points posted so far. I've received some useful information.

Biggest problem I see is it will very hard to tell if this makes a difference unless it is a huge difference for the better or worse.

I'm still gonna try it. It will only cost me some time and the $$ for the foam. I'll take pics and try to provide some measurable proof of any performance gains...

I still find it hard to believe that the air has to travel through such a restricted set up. Haven't they learned that getting cool, unrestricted air into the carb is vital to performance.

Could it possibly be that the off throttle bog we all experience is simple the bike choking for air?

Guys, improvements can be made on the airbox set up, we just have to bring all of our knowledge together to make it happen. This is the site that has tons of useful performance mods that don't cost jack. I truly believe the airbox is the next cool mod...


  • motojunkie

Posted April 01, 2002 - 01:13 PM


Ben, just make sure that your air box is sealed, and won't allow any dirty air in. You probably won't notice any difference until the filter gets dirty, then it will be worse than stock. It seems to that you are just moving where your air restriction is. If you want gains, get more air into the air box using the stock filter arragement. You can do that by installing the 1" filtered vents into your airbox. Hope this helps. Later.....Tom

  • neWRiver

Posted April 01, 2002 - 01:29 PM


Maybe I'm missing the point here, but why have an air box at all if the filter is on the outside? How will moving the filter allow more airflow unless it provides a larger filtering surface area?

  • armourbl

Posted April 01, 2002 - 02:13 PM


Well, in the street world we have RAM air. We also have airboxs without RAM air. In both cases, a bigger airbox that allows more air flow will improve performance. Filters have always precented a "wrench in the gears" effect to this theory.

They take up valuable space in the airbox.

I'm no scientist or physics major, but the way I understand it is, the air box provides for a pressurized chamber for the carb to draw air -- keeping a high volume of air on hand for immediate power demands.

The pressure on a RAM air systems is developed by forcing air into the airbox with shear velocity. The pressure on a non RAM system is developed by a vaccum effect from the carb and the normally restricted airbox intake. Or something like that anyways.

Ok, our air filters take up a lot of space in the airbox, more than half for sure. This doesn't allow much space for the incoming air to occupy. The limited space doesn't allow for the air to get turbulent, or resinate.

You are right, I'd be moving where the air is restricted. I think moving it further from the carb intake will simply allow for better final flow and may help increase the airbox air pressure, allowing more air to be available at a moments demand -- say a handle full of throttle on the face of a jump.

Like I said, I'm no expert on the physics of all this, but if this is possible as a performance improvement, we can develop it together as member of TT.


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