Airbox design

CR500Rider
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CR500Rider
Edited Date/Time 1/26/2012 3:35pm
I'm not talking about the boot that connects the airbox to the carb, just the airbox itself. Does it really serve a purpose other than to keep water out and something from tearing the filter off? I have the big idea that I'm gonna TIG up an aluminum airbox in the near future.
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xnationalwrench 5/17/2009 1:36pm
5/17/2009 1:36pm
The airbox is a still air box that provides plenty of air for the carb to breathe. If the box is too small it will resrict air going to the carb and limit horsepower, you need for the airbox to be able to pull air into it and still limit any dirt or debris from following the air in also.
CR500Rider
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CR500Rider 5/17/2009 2:01pm
5/17/2009 2:01pm
xnationalwrench wrote:
The airbox is a still air box that provides plenty of air for the carb to breathe. If the box is too small it will resrict...
The airbox is a still air box that provides plenty of air for the carb to breathe. If the box is too small it will resrict air going to the carb and limit horsepower, you need for the airbox to be able to pull air into it and still limit any dirt or debris from following the air in also.
The intake boot I'm using won't quite line up with the stock airbox and I'm not into the heat and stretch method. We've all seen the dirt trackers run slip on air filters. I even run the slip on filters on my 66' Yamaha YM1. I guess what I'm really asking is, is the airbox basically there to protect the filter or does it perform some other tuning function?
xnationalwrench 5/17/2009 5:27pm
5/17/2009 5:27pm
Dirt trackers don't usually do mud or water.
CR500Rider
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CR500Rider 5/17/2009 6:58pm
5/17/2009 6:58pm
xnationalwrench wrote:
Dirt trackers don't usually do mud or water.
I think we're agreeing cause that's kind of my point! "IF" we didn't encounter that in MX, we'd probably run the same thing for superior air flow. Hence, I'm thinking the only real purpose of the airbox is to keep water and chunks of dirt and rocks from hitting the filter while struggling in some cases to get enough air into the engine. My reference to the dirt trackers was kind of saying "if an airbox was necessary (for anything but protection), they'd probably be running one. Thanks for discussing.

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lumpy790
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lumpy790 5/18/2009 1:45pm
5/18/2009 1:45pm Edited Date/Time 4/16/2016 11:58pm
I have seen dyno runs where they remove the air box and just run a big K&N filter but......Big HP loss everywhere except WFO......so why do it?
CR500Rider
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CR500Rider 5/18/2009 7:51pm
5/18/2009 7:51pm
lumpy790 wrote:
I have seen dyno runs where they remove the air box and just run a big K&N filter but......Big HP loss everywhere except WFO......so why do...
I have seen dyno runs where they remove the air box and just run a big K&N filter but......Big HP loss everywhere except WFO......so why do it?
I'm not sure you can get a slip on air filter to even fit with the aluminum frame and the carb jacked to one side on a CR125. I'm not planning on doing it anyway, it was just a question of if I fabricate an airbox and get at least as big as the stock, it should be ok.
lumpy790
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lumpy790 5/19/2009 7:45am
5/19/2009 7:45am Edited Date/Time 4/16/2016 11:58pm
If you make the alum air box to the same dimensions it will work the same power wise.

Back in the day there was a company by Chicago that imported super trick aluminum parts like gas tanks & a sub frame with the air box made into it.....I think it was on the line racing.

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