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Wes Woodin

James Stewarts New BIKE!

34 posts in this topic

have you noticed the pictures of Stewarts YZ at indy from transworld that you cant see carby breather pipes?

is his bike already running FI ?

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For more power...

Not kidding.

Well I realize that. . I am not stupid. But it doesn't look like that when he is racing they must have some kind of cover for it maybe? That is what I am more curious about how do they cover it up??????

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....and you will notice that the cut-outs are only on the left side. They dont want the right side to be cut for sound requirements. There is a chance that if it was open, the added noise from the intake would make it fail sound check.

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Really that is pretty interesting I will have to check it out at the Seattle SX I am taking my 4 year old son-the one in my avatar- to the pit party.

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Why are the sides of his airbox cut away??
For more power...

Not kidding.

I doubt it. The existing air path into the filter element of a standard YZ450 is already at least 4 times larger than even a bored out carb. In order for the cut out in the air box to be of any benefit, the existing setup would need to be restrictive enough to drop pressure below atmospheric in the air box at the outside of the element.

In '04, I believe it was, Doug Henry's Super Moto team experimented with several reconfigurations of the air box, including cut outs and removing the flame screen, and found no advantage on the dyno to any of it. They did see a very small improvement in one configuration, but only at speeds above 90 mph.

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have you noticed the pictures of Stewarts YZ at indy from transworld that you cant see carby breather pipes?

is his bike already running FI ?

Nope, his bike has to have a carb by AMA rules. His vent tubes are likely tucked into the skid plate.

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I doubt it. The existing air path into the filter element of a standard YZ450 is already at least 4 times larger than even a bored out carb. In order for the cut out in the air box to be of any benefit, the existing setup would need to be restrictive enough to drop pressure below atmospheric in the air box at the outside of the element.

In '04, I believe it was, Doug Henry's Super Moto team experimented with several reconfigurations of the air box, including cut outs and removing the flame screen, and found no advantage on the dyno to any of it. They did see a very small improvement in one configuration, but only at speeds above 90 mph.

....

Power has been shown, heck, here is a link for a honda 450 that details it.

http://www.gomxracing.com/forum/showthread.php?t=31670

If not done so already...register and you can see the images...

On a mod bike....it becomes extremely important.

Now maybe henry's didn't make more power. Maybe his set up didnt' need it (though for supermoto you would think he is cranking out a lot of hp...)

But either way, stewart is running it! Maybe he has a trick up his sleeve for a finish line victory celebration...air box grap bubba scrub or something

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Now maybe henry's didn't make more power. Maybe his set up didnt' need it (though for supermoto you would think he is cranking out a lot of hp...)

Henry's bike wasn't a Honda at that time. The YZF has a much roomier air box, and a cleaner path into it. CRF's also appear to benefit from removing the flame screen, but again, it had no effect on the YZ450 when it was tried.

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Im sure they are running that setup for some performance gain, power or weight savings. Im sure every ounce counts for them.

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Quote:

Originally Posted by 299RACER

have you noticed the pictures of Stewarts YZ at indy from transworld that you cant see carby breather pipes?

is his bike already running FI ?

Nope, his bike has to have a carb by AMA rules. His vent tubes are likely tucked into the skid plate.

why couldnt he run efi, if yamaha was doing it for testing

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why couldnt he run efi, if yamaha was doing it for testing

He has to run the bike the way it is produced. i.e. JS can't run a steel framed 450. Remember when McGrath rode for Honda he was running a '93 frame for like five years and when they switched to aluminum he hated the frame so he switched brands.

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You can run a pre-production prototype for one year, then it has to be a production unit to a very large degree. That's how they were able to run this bike in 1997:

YZM400F2sm.jpg?t=1236040199

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Seeing that bike makes me all warm and fuzzy I knew there was some stipulation just couldn't quite remember. Thanks for clearing that up. So he can only run it if it is going to be production in 2010? I would sure like to see a test bike from the Factory guys over in Japan.

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