It’s all up in the air! Aside from keeping us alive as we breathe it, air keeps our engines alive and running—in more ways than one. I’d like to address a couple of those ways. They might seem like they have nothing in common, but the simple fact is, all the devices I intend to discuss in this column depend on air, try to control some of its characteristics and quite simply would not do anything at all if it wasn’t for the fact that air is so intrinsic to the functions (and byproducts) of internal combustion.
Now—hot and cold running Harleys
I’m pretty much on record stating that nobody really understands the mysteries of airflow (other than you have to have it). Oh, there are plenty of folks out there who’d like to think they do, but beyond certain fundamental “givens” there’s still a lot to learn—if you have an open mind. Case in point: My old friend Frank Kaisler, former editor of Hot Rod Bikes and serious gearhead, used to do a neat trick whenever he dyno-tested drag pipes (which he did hundreds of times over the years!). Where he learned it, I don’t really know, but it was sufficiently impressive that Samson (as in exhaust) sells a gadget to this day that effectively emulates Frank’s old trick—and it still works! This was the deal: You’d make a pass with a set of straight pipes, look at the chart for the horrible hole where the torque used to be, then lay a screwdriver across the end of the pipe and make another run. Voila! The torque came back pretty damn well. One supposes this is be­cause a simple bit of steel bar in the middle of the exhaust tip added some of that vague stuff we call “back pressure” and the motor liked it. Who really knows?
Thing is, one of those fundamental givens in airflow is simply that the middle of any round tube (like an exhaust pipe) is invariably a dead zone for flow. (You can see this for yourself every time you drain a bathtub or sink with the little screen out.) Flow (water down drain, air through your induction manifold) actually occurs at and near the walls, not in the center. So, my theory is, adding the width of a screwdriver to the typical 1 3/4″ diameter of a drag pipe outlet simply created two smaller, more turbulent outlets for the exhaust. Who really knows?
What is known is that engines like this kind of thing. There are two new “induction” products on the market that employ the notion of “minimizing the dead zone,” in what could be a very effective fashion, in terms of air flow.
Throttle by wire—airflow by foil
Boyesen X-Wing airfoils—to be more precise. 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
The Boyesen X-wing
One of these installed in the throttle body of any 2008 or 2009 “throttle-by-wire” touring Harley should provide noticeable improvements in “snap” from an otherwise fairly sluggish, EPA-mandated, electronically controlled twist grip. (Can’t really call it a throttle anymore.)
The Pow-R-Port
In the first place, this doesn’t really look like an ordinary intake manifold for carbureted Harleys…
…and that’s because it isn’t! The Pow-R-Port manifold, by LAH Engine Development, might be just the ticket for getting the most cooperation from the least cooperative component on what are now old school Harleys. Namely, any carbureted hog hot rod! Getting de­cent throttle behavior and good power at lower rpm, with no loss (or compromise) at WOT, has been a touchy tuning prospect at best in the past. This manifold with its variable venturi technology might just make all of that a thing of the past!
Teaching old “bogs” new tricks
Unlike modern EFI systems where you can treat the intake system almost like a still air box and get away with it, carburetors absolutely require decent air flow velocities to work. That the term “overcarbureted” is practically a cliché should be proof enough of this truism. Of course, certain carb designs are more likely to misbehave than others, mostly at low speeds with big handfuls applied suddenly and un­ceremoniously. There are (sort of) three primary types of Harley carbs: “slide” (Mikuni, Dell’Orto), “butterfly” or throttle valve (S&S, Bendix, Linkert) and a hybrid with both elements, we typically call “CV” (or constant velocity) like Keihin and SU carbs. Generally speaking, the CV is the most forgiving and adaptable, the slide offers the best throttle response, and the butterfly (although a great WFO performer) is the toughest to tune for all throttle openings. Again this has to do with air flow, particularly in the case of butterfly carbs, at small throttle openings when you suddenly want to slam the thing wide open. Anyone with a big S&S Super B on a small motor knows what I’m talking about when I say this can lead to the dreaded “bog” all too easily. Older Linkerts and Bendix carbs suffered as well, all of which led to less and less use of these carbs and the addition of an accelerator pump on the S&S Super E and G, to mask this unfortunate tendency. For performance work, the issue isn’t total volumes of air passing under the butterfly (because Lord knows there’s plenty), it’s the velocity. Air moves faster than fuel so when you pop the butterfly flat in a rush, the fuel can’t balance the air instantaneously and it’s Bog City! In the past, that meant you realistically had to use a carb that was small enough to avoid bogs and were thus forced to sacrifice a little top-end power. Conversely, if you used as much carb as the engine could handle wide open, your bike would take a lot of “nursing” at the throttle to be rideable in day-to-day stop-and-go situations. In other words, serious compromises have to be made that just get worse with radical cam timings and high compression.
Well, LAH engine development, out of Miamisburg, Ohio, might just have reduced your worries to a minimum, at least about this kind of thing! They have created the so-called Pow-R-Port intake manifold, to lessen or eliminate these gross compromises in carburetion. Once more we see that the trick is performed by controlling air flow, in this case with the use of a moveable stainless steel flap inside the manifold body. The company calls it VVTM for “variable valve timing manifold,” but I prefer variable venturi throat manifold. Either way, and by any name, the flap is there, to keep the venturi diameter smaller at low throttle openings to improve both power curves and throttle re­sponses (OK, transitions) on any Harley. To me the real benefit is that air has to move that flap, which gives fuel time to catch up, which means a more precise mixture and far less chance of “bog” on high-powered machines with carbs big enough to do their best at WFO. I haven’t (yet) had a chance to do any dyno testing, but my instincts are that the Pow-R-Port will do for carbs (particularly the butterfly type) what Frank’s screwdriver did for drag pipes. Namely, boost all the power “under the curve” whether or not it adds anything to peak power. To learn more call 937.866.5668 and ask for Gene or hop on the Web at
How hot engines keep their cool
Let’s wrap up our air flow treatise with a look at a product that uses air flow for a much different purpose than making more power. Rather, it’s designed to dissipate the heat that powerful engines generate.
Most oil coolers on the market don’t control oil temperature. They only cool it, and they do that only when you’re moving. Yet your motor needs cooling just as much (if not more) when you’re stuck idling in traffic.
There’s a new oil temperature control system soon to hit the market called Ultra Cool that actually controls oil temperature. It has three components: a regulator that allows oil to circulate through the cooler only when it reaches a temperature above 160 degrees (needed for warm-up to allow the oil in the engine to lubricate properly); a thermostatically controlled, high-output fan that pulls air through the oil cooler when the oil temperature goes above 210 degrees and automatically shuts off when it drops to 190 degrees (and works even when you’re standing still); and a cover that keeps out debris.
The Ultra Cool oil cooler
Installed (although not as quickly and easily as some), it looks pretty handsome, what with its nice cover and all. But it’s the function of the Ultra Cool that makes it truly a beautiful thing!
Here’s the “inner sanctum” of the Ultra Cool. It’s compact and effective and should have been invented years ago. The simple fact that it works sitting still, and effectively, automatically maintains proper uniform oil temperatures under all conditions should be a clue as to how advanced this design is, compared to regular oil coolers. Hey—who needs a radiator anyway?
I recently had the opportunity to install one of these coolers and frankly, I’d buy it! It promises to do something long overdue in the motor­cycle arena, and as the attached pics hopefully show, it’s not bad looking either. I can’t (yet) attest totally as to the functionality of the Ultra Cool, because my “lab rat” is a on a ride through Russia (yeah, Russia!) as this is being written. However, aside from the fact that I have a couple of issues with Ultra Cool’s use of a Jagg’s adaptor—which can (without due care and caution during the in­stall) later come loose—I’m certain it works as adver­tised. Mind you, for all I know those critical thermostatically controlled fans are off an old desktop computer. Nonetheless, this is one of those “Why didn’t I think of that” improve­ments over anything else on the market. For those who already have an oil cooler, factory or aftermarket, the story goes that Ultra Cool’s creator, one Marlon Moss, is also going to offer an upgrade kit to add thermostat and fan where none came before! For more information, you can visit the website, or just give Marlon a call at 831.207.3394 and he can explain why a cooler that works independently of “natural” airflow is really an oil temperature control system!
The point is, whether you want your Harley to run “hotter” or keep its “cool,” ya gotta go with the flow—air flow, that is!


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