Yoshimura Hayabusa X-1 - Heavy Bus

Well, what would you do in the off-season if you worked for Yoshimura R&D; U.S. and found a Suzuki GSX1300R Hayabusa lying around? You'd ransack the candy store, that's what, especially if your pipeline to Yoshimura Japan was expectorating tasty chunks of Hayabusa Formula X racer. The Formula X bike not only won its class at the last Suzuka 8-Hour, beating all sorts of Yamaha R1s and Kawasaki ZX-9Rs, it also qualified on the tail of Noriyuki Haga's factory Yamaha YZF-R7 in the process, and finished 12th overall. Hai! It's a little bigger and heavier, but you can get more power from 1300cc than you can from 750, can't you? Let's see, that's, ahhh, 550cc more-very damn near a GSX-R750 and a 600. Now all we need to do is find somebody crazy enough to ride it. Where's that Gobert guy?

In the land of the rising sun, Fujio Yoshimura-son of Pops-believes in racing what people can buy, not just exotic factory superbikes. Hence Yoshimura's Hayabusa X1-R-or "Heavy Bus" as Yosh mechanics soon dubbed it. Very commendable.

Meanwhile back in Chino, California, at Yoshimura R&D; of America Inc., just because you're Mat Mladin's crew chief by day-like Ammar Bazzaz-doesn't mean you're immune to the lure of highly cool toys. Co-conspirator and Yosh marketing guy Doug Wells has a full-blown '86 Yoshimura superbike in his living room and a bad hardware bug. Wells gave up a job piloting tourists to his native Bahamas to fondle hardware at Yoshimura. When an innocent, box-stock Hayabusa somehow found its way into the shop, no way was it going to escape unsullied. It had no chance.

Seeing as how an unmolested 'Busa already makes a reasonably frisky 160-ish horsepower and 99 foot-pounds of torque, Ammar and the kids decided not to emulate the Japanese Formula X racer too closely in the engine department. (At one time the racing 'Busa made 225 horses, but tires wouldn't live under it so it was "detuned" to around 208-barely enough to get out of its own way.) What you're looking at here, believe it or not, is destined to be a streetbike at some point, so Yosh went with a mild engine tune-only 182 horses and 108 foot-pounds of torque. Stage One billet cams, a little porting, 12.5:1 forged pistons, Carrillo 4340 rods, that type of thing, move the power peak up to around a nice, safe 10,500 rpm and the torque peak to 7500. Runs on pump gas, Ammar says, but what's that sweet smell?

Since they were in there anyway, Yoshimura yanked out the stock engine counterbalancer-though Falicon did such a nice job polishing and balancing the 2.5-pound-lighter crankshaft you'd never notice.

MoTeC (www.motec.com) of Australia, having already proved itself in auto racing, is moving into bike electronics and provided its mondo-megabyte military-spec M48 engine controller, which directs the stock fuel injection. MoTeC also makes the bike's data-logger, which displays comprehensive real-time data on the LCD dash while storing all manner of information for later reference. Since the logger uses the same sensors as the engine controller, all that connects logger to controller is a two-wire serial connector; simple and light.

Heck, with MoTeC's lambda sensor telling you the exhaust's oxygen content at any given rpm, under any load, you really don't need a rider to help you get the jetting perfect, do you, Ammar?

Wrong again. A good rider is still critical to making the bike work right, and a guy like Aaron Yates, who's particularly good with carburetion since he worked on his own for so long, is able to use the in-flight dashboard's lambda display (lower left on the LCD dash) and throttle position indicator (lower right) as another really useful tool in making the engine run as hard and smooth as possible.

Proven rock-steady in Formula X, there's no reason to fool with the bike's frame, really, except that you can. As on the racebike, then, Yosh added a GSX-R superbike swingarm-which shortens the wheelbase 25mm-and a kit hlins fork carried in kit superbike magnesium triple clamps (30mm offset keeps the front wheel from scraping the fairing's chin).

Ammar was a Harvard-educated mathematician before the bike bug hit him 11 years ago, at 20, and he enjoys nothing more than figuring out which combination of hlins spring and dampers is needed out back to make the Yosh swingarm linkage work. Less progressivity, or rising-rate, is the way to go on the track; that keeps damping consistent throughout the stroke.

Nice of the Yoshimura people to truck their completed X1 out to the track for us to get a test ride, wasn't it? Who wants to go first? Listen, why don't you go? I feel fat in these leathers, a little bloated.

From the beady tip of its 8-Hour headlight to the smooth blended-in-ness of its LED taillight, this bike sitting on its stand reminds you of a nicely mounted, well-fed Carcharodon: You don't want to get too close, just in case it suddenly reanimates and starts snapping. Even after losing all the street equipment and adding the Ti pipe, Marchesini wheels, etc., the thing still weighs just under 500 pounds full of fluids. The tail-section/seat sits two or three inches higher, too, for cornering clearance.

The s#*t is big.
The starter motor is likewise afraid to disturb the bike. Either the superbike charging system's not strong enough or the MoTeC drew too much juice while we stood around playing with it or there's just too much compression; in any case a classic bumpstart is in order. Switching on the ignition and opening the throttle all the way once lets the computer know to feed the gas when the wheels roll.... A hearty shove from the lads and KAHBHWHUBWHUBWHUBWHUB...sounds like one of Wes Cooley's old 1000cc Yoshimura Superbikes from back in the day. Away you go.

Stretched out across the 24-liter aluminum quick-fill fuel tank like a lobster ready for boiling, you pull onto the track, a light squealing just beginning to emerge as your carapace heats.

Suspension's firm, eh? Apparently Ammar, accustomed to helping clients such as Mladin, was expecting us to hop on here and circulate in a like manner. Maybe later, like in a different lifetime. For now we'll sample the top inch or two of suspension travel whilst attempting to defamiliarize ourselves with all of Willow's highside zones.

Oh well, at least we can use the motor once we get to the back straight. Did we use the term "sneaky-fast" last month in describing Honda's RC51? Well then, this Hayabusa is top-secret, clandestine, John LeCarre-in-a-trenchcoat fast. On the move you can barely hear the motor, and as the cool LCD tach bar moves and fattens toward the little seven it occurs to you you've already arrived wherever it was you were going a second ago. Most bikes you need to keep spinning, wait for some revs to come up; this one doesn't require more than just a few. Factory-prepared 750 Superbikes might make nearly as much peak horsepower as this bike, but you can rest assured none of them approach 108.6 foot-pounds of torque at 7500 rpm. The Bus also wears a one-tooth-smaller rear sprocket than stock, and feels like it would blow right through 200 mph in its mirrorless, turnsignal-less, race bodywork. Heck, maybe it just did?

Eek, tiptoe through turn eight through the ripples. Clip-ons jostling from fist to fist is the Bus's way of saying: C'mon ya little runt, you're gonna hafta give it more than that for this relationship to work

Alrighty then, you cranky bastard, you think you're so tough, we'll see about that down the long front straight (but no way we're opening this throttle 'til we're straight up and down). Even then there's wheelspin.

Turns out it's true. It is even faster up toward 10,000 rpm. In fact, once the tach moves past eight grand things begin to happen real suddenly as that lightened crank spins smoothly up toward God-knows-where. All the way down Willow's half-mile front straight feels like an inch-high power wheelie, handlebars giving a little whack over each bump. Must you do that?

Shuddup and hold on ya pipsqueak. Hey! What are you doing? You're not squeezing my brake lever already are you...the turn's down there at the end of the straight.

Why yes, as a matter of fact I am. My eyes are joggling around like golf balls in a garbage disposal and I want to leave plenty of room. The brakes seem way more than adequate-crisp and mighty powerful. Between them and the monster motor I develop a new "style" for riding the X1 at Willow: brake hard way early, squint, reascertain the vicinity of the corner, accelerate again up to it, brake again, turn.

The plot begins to thicken and gel after a couple more laps, though, and you eventually learn to trust the beast, which is big and powerful and omnivorous and must keep water pouring over its gills at all times, yet turns amazingly light and quick and feels better the faster you go. Still there's that feeling you get in the company of pit bulls you don't know well, or from people you meet in jail.

I have a vague comprehension that someone who knows what he's doing could make serious, tire-spinning time on this monster, but that rider would possess huge skill and reproductive organs also not to scale. (Maybe that's why the seat's so high?) It's a 500-pound object, dear, and while its limit is a ways out there, you'd eventually grow familiar enough to explore the perimeter. You just know that when you step over the line with this bike, gathering things back up could be like attempting to shove toothpaste back in the tube at a very high rate of speed while wearing thick gloves. All the power in this bike reminds us of the old saying about rain tires: They simply allow you to crash at a higher rate of speed.

But as a streetbike, which is what this Hayabusa's supposed to be, what could go wrong? On the street, unless you're insane (and you won't be for long on this thing), you're only going to access that power in very short, impressive bursts that will amaze your friends and influence people wherever you go. And then you'll sit there with a double-espresso, heart pumping like a Yosh-kit fuel pump, and just admire the audacity of the thing and the loons who would dare to race it, and you have to laugh. Yoshimura has known it all along: Nothing succeeds like excess.

Turbo 'Busa
If you think northern Sweden is no place to base a motorcycle tuning firm, Erik Marklund of MC Xpress would disagree. "Because it's so cold and dark almost all the day in winter, we have plenty of time to work on the bikes," he says. "And in the summer it's light almost all the time and often hot. We have some nice straight roads with not many people or cars or police, so it's great for riding fast."

Erik has built a string of ultrapowerful specials since founding MC Xpress 10 years ago-turbo kits for sportbikes being the house special. He sold around 100 turbo kits all over the world last year. His latest and most outrageous project: the turbo Hayabusa.

The effort to cram the turbo into the very compact 'Busa was worthwhile. With its wastegate set at a not-too-radical 11.6 psi, the bike produces 328 hp at 9000 rpm at the crank-almost double the standard claimed max of 173 hp-and kicks out more than the stock Suzuki everywhere above 6000 rpm. Weighing little more than the standard bike, the big blown 'Busa has an almost identical power-to-weight ratio as Honda's NSR500 works GP bike.

The Mitsubishi turbo, used in some Volvo cars, is particularly suitable due to its built-in "pop-off" valve. "When a normal turbo is boosting and you close the throttle, the air has nowhere to go and produces a big pulse," Erik says. "This can destroy the hoses and intercooler and also means the turbo stops running, so if you open the throttle again you have no boost." Normally a separate valve is used to prevent this, but it's unnecessary with the Mitsubishi design.

Space was so tight in front of the engine Erik had to chop off the turbo's main air tube leading to the air box and reweld it to exit in a different direction. The standard Suzuki oil cooler and radiator are retained, but the rad is modified to make room for a large curved-aluminum intercooler (made by Erik) which cools intake air en route to the motor.

The standard fuel injectors are retained, but Erik adds a new bank of four Bosch injectors along with a new aluminum air box, a second fuel pump (the original is also used) and a fuel-pressure regulator. The original control unit for ignition and fuel-injection is unmodified.

The engine has to be stripped so that a 2mm aluminum spacer can be added to the bottom of the cylinder barrel, reducing compression to 8.5:1 from the standard 11.0:1. Stripping the motor is the hardest part of fitting the turbo kit, Erik says.

The kit costs $6000 through American Turbo Systems and includes an adjustable intake camshaft sprocket (to compensate for the spacer), bigger front final-drive sprocket, stiffer clutch springs and a stainless steel exhaust with carbon can. -Roland Brown

Importer:
American Turbo Systems
3435 Enterprise Ave. #50
Naples, FL 34104
Tel/fax (941) 403-0198
www.americanturbo.com

Yoshimura X1