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Discussion Starter #1
So I was looking at my 748 thinking about some things and I wondered why the cut outs in the side fairing are facing the opposite way of the wind flow on the bike. It seems to be a bit counterintuitive to me. If the purpose is to actually bring air in to cool the engine it seems they should face the other way to better "scoop the air up"?

If somebody can explain how this works that would be great. I've noticed quite a few bikes like this so there must be some theory behind it.

Maybe it causes a suction as the air passes over the cut outs?
 
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Re: How do the cut outs on the side fairing work? (themagicalswitch)

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by themagicalswitch »</TD></TR><TR><TD CLASS="quote">Maybe it causes a suction as the air passes over the cut outs?</TD></TR></TABLE>

....and draw air through the radiator.
 
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Re: How do the cut outs on the side fairing work? (Mental998)

I think it has something to do with creating an area of negative pressure, which, as Layne said, "pulls" the air through the rads.
 
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Re: How do the cut outs on the side fairing work? (DesmoBob)

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by DesmoBob »</TD></TR><TR><TD CLASS="quote">I think it has something to do with creating an area of negative pressure, which, as Layne said, "pulls" the air through the rads.</TD></TR></TABLE>

Yup
 
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Re: How do the cut outs on the side fairing work? (themagicalswitch)

As the bike moves through the air, air stacks-up in front producing a higher air pressure at the front of the radiator. If there were no air outlet holes in the fairing, the air pressure inside the fairing would be the same as that in front of the radiator, so there would be no differential pressure, and consequently no air flow through the fairing. The cut-outs are simply there to exhaust the air but are also placed at a point at the trailing edge of the fairing where there's a lower air pressure - so they also help to pull air through.

A good example of an air scoop design is the NACA duct in the lower right fairing that is used to cool the voltage regulator.
 
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Re: How do the cut outs on the side fairing work? (Shazaam!)

998 has the same bodywork but deals with this issue differently. More than one one way to skin a cat.
 
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Re: How do the cut outs on the side fairing work? (themagicalswitch)

Yeah I've always wondered why the 998's didn't have the side exhaust ducts. What's different about their cooling needs that doesn't neccessitate those ducts? Or does that just mean that the exhaust ducts on the 748/916/996's are purely aesthetic?
 
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Re: How do the cut outs on the side fairing work? (ten~39)

998 doesn't have side ducts, but there are screens at the trailing edge where the earlier bikes have a solid piece.
 
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Re: How do the cut outs on the side fairing work? (Buckelew)

Is dat due ta dat daarre venturi effect?
 
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