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Posted Date: 2012-06-11
Throttle by wire - airflow by foil
Kip Woodring of Thunder Press discusses airflow tuning for Baggers
Originally Printed: Thunder Press Online Article
Written by: Kip Woodring

For those who might not be familiar with two-stroke technology, the company who makes these so-called X-wings made their reputation (a damn good one) primarily by messing around with reed valves on dirt bikes. Boyesen reeds are justly renowned in the hot rod two-stroke market. And, if air flow in four-stroke engines is still moderately mysterious, getting it figured out in engines with no poppet valves, which breathe through ports from the crankcases, is a flat out conundrum! Yet, for many years Boyesen has mastered the art of getting more performance via tweaked airflow. Now, they've come to market with the X-wing for Harleys. The basic concept would seem to be along the lines of Frank's screwdriver trick, but applied to intake air flow-namely to trick large masses of dead air into flowing faster and with controlled turbulence.

Airfoils (as in airplane wings, for example) work by changing the speed and direction of air movements-period. Whether it's getting an airplane to lift off the ground, a race car to stay firmly on the ground, or any dead flow zone to wake up and move some air, the principle remains the same. Boyeson reasons that by dividing up the large area of the "intake" (throttle body or carb) into essentially smaller vortexes with higher velocities, one will get (due to reductions in dead flow) better throttle response, superior power delivery and other tasty little benefits along those lines. I personally figured this was fairly incremental, when it came to using an X-wing on most Harleys. Then came 2008 touring bikes, with huge throttle bodies, inviolate electronically controlled butterflies and no cables to cope! In a nutshell, tuning throttle-by-wire EFI systems on '08 and '09 baggers is an exercise in frustration because of this lack of control over air flow. You can add fuel and mess with timing as before, but the bike's "brain," rather than the rider's right wrist, is really in charge of how much air gets in the engine at any given time, under any situation.

Anyone who's bothered to look can verify this tends to happen at lethargic rates, with an enormous butterfly moving through its arc at a snail's pace through the first 30 percent of its travel. Enter the Boyesen X-wing! It might not cure everything that ails the factory setup, but it stands to reason that on "built" engines any tendency toward sluggish response when you grab a handful (of electrons?) would be improved notably. Breaking up intake air flow through that gigantic 2008/2009 factory throttle body, into four smaller, faster-flowing vortexes, should make for a better situation all around. It sure couldn't hurt! Besides, for now, the X-wing is the only game in town for tailored airflow on late-model TBW baggers. For more techno-babble and retail sources for an X-wing visit
Keywords: Thunder Press, Power X-Wing, HD Touring Bikes, Airflow Control, Bagger Parts, V-Twin Performance, Boyesen V-Twin Products, Motorcycle Parts, Harley Davidson Power, Bagger, Custom Motorcycles, Custom Choppers, Custom Harley Davidson
About Boyesen
For more than 30 years Boyesen has specialized in the design and manufacture of high-performance parts to the power sports industry. The confidence instilled by Factory Race Team Research and Development partnerships bleeds all the way down to weekend warriors looking for the highest performing and longest lasting products on the market. Boyesen's tagline, "Leading Edge Performance", is recognized worldwide. From their innovative industry leading performance reeds, to their complete intake track System, Boyesen continues to consistently set the standard for performance and manufacturing build quality.
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