Yoshimura Hayabusa X-1 – Heavy Bus

Yoshimura Hayabusa X-1- Heavy Bus

The StreetVersion Of Yoshimura's 200-Horse Formula X Hayabusa Racer StopsWherever It Wants

Photography by Hiroshi Sato, Kevin Wing, Phil Masters

Motorcyclist, September 01, 2000


Yoshimura Suzuki Hayabusa X 1 Side View

Well, what would you do in the off-season if you worked forYoshimura R&D U.S. and found a Suzuki GSX1300R Hayabusa lyingaround? You'd ransack the candy store, that's what, especially ifyour pipeline to Yoshimura Japan was expectorating tasty chunks ofHayabusa Formula X racer. The Formula X bike not only won its classat the last Suzuka 8-Hour, beating all sorts of Yamaha R1s andKawasaki ZX-9Rs, it also qualified on the tail of Noriyuki Haga'sfactory Yamaha YZF-R7 in the process, and finished 12th overall.Hai! It's a little bigger and heavier, but you can get more powerfrom 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 weneed to do is find somebody crazy enough to ride it. Where's thatGobert guy?

In the land of the rising sun, Fujio Yoshimura-son ofPops-believes in racing what people can buy, not just exoticfactory 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 ofAmerica Inc., just because you're Mat Mladin's crew chief byday-like Ammar Bazzaz-doesn't mean you're immune to the lure ofhighly cool toys. Co-conspirator and Yosh marketing guy Doug Wellshas a full-blown '86 Yoshimura superbike in his living room and abad hardware bug. Wells gave up a job piloting tourists to hisnative Bahamas to fondle hardware at Yoshimura. When an innocent,box-stock Hayabusa somehow found its way into the shop, no way wasit going to escape unsullied. It had no chance.

Seeing as how an unmolested 'Busa already makes a reasonablyfrisky 160-ish horsepower and 99 foot-pounds of torque, Ammar andthe kids decided not to emulate the Japanese Formula X racer tooclosely in the engine department. (At one time the racing 'Busamade 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 astreetbike at some point, so Yosh went with a mild engine tune-only182 horses and 108 foot-pounds of torque. Stage One billet cams, alittle porting, 12.5:1 forged pistons, Carrillo 4340 rods, thattype of thing, move the power peak up to around a nice, safe 10,500rpm and the torque peak to 7500. Runs on pump gas, Ammar says, butwhat's that sweet smell?

Since they were in there anyway, Yoshimura yanked out the stockengine counterbalancer-though Falicon did such a nice job polishingand balancing the 2.5-pound-lighter crankshaft you'd nevernotice.

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

Heck, with MoTeC's lambda sensor telling you the exhaust'soxygen content at any given rpm, under any load, you really don'tneed a rider to help you get the jetting perfect, do you,Ammar?

Wrong again. A good rider is still critical to making the bikework right, and a guy like Aaron Yates, who's particularly goodwith carburetion since he worked on his own for so long, is able touse the in-flight dashboard's lambda display (lower left on the LCDdash) and throttle position indicator (lower right) as anotherreally useful tool in making the engine run as hard and smooth aspossible.

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

Ammar was a Harvard-educated mathematician before the bike bughit him 11 years ago, at 20, and he enjoys nothing more thanfiguring out which combination of hlins spring and dampers isneeded out back to make the Yosh swingarm linkage work. Lessprogressivity, or rising-rate, is the way to go on the track; thatkeeps damping consistent throughout the stroke.

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

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

The s#*t is big.

The starter motor is likewise afraid to disturb the bike. Eitherthe superbike charging system's not strong enough or the MoTeC drewtoo much juice while we stood around playing with it or there'sjust too much compression; in any case a classic bumpstart is inorder. Switching on the ignition and opening the throttle all theway once lets the computer know to feed the gas when the wheelsroll…. A hearty shove from the lads andKAHBHWHUBWHUBWHUBWHUB…sounds like one of Wes Cooley's old 1000ccYoshimura Superbikes from back in the day. Away you go.

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

Suspension's firm, eh? Apparently Ammar, accustomed to helpingclients such as Mladin, was expecting us to hop on here andcirculate in a like manner. Maybe later, like in a differentlifetime. For now we'll sample the top inch or two of suspensiontravel whilst attempting to defamiliarize ourselves with all ofWillow's highside zones.

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

Eek, tiptoe through turn eight through the ripples. Clip-onsjostling from fist to fist is the Bus's way of saying: C'mon yalittle runt, you're gonna hafta give it more than that for thisrelationship 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'reopening this throttle 'til we're straight up and down). Even thenthere's wheelspin.

Turns out it's true. It is even faster up toward 10,000 rpm. Infact, once the tach moves past eight grand things begin to happenreal suddenly as that lightened crank spins smoothly up towardGod-knows-where. All the way down Willow's half-mile front straightfeels like an inch-high power wheelie, handlebars giving a littlewhack 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'sdown there at the end of the straight.

Why yes, as a matter of fact I am. My eyes are joggling aroundlike golf balls in a garbage disposal and I want to leave plenty ofroom. The brakes seem way more than adequate-crisp and mightypowerful. 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 bigand powerful and omnivorous and must keep water pouring over itsgills at all times, yet turns amazingly light and quick and feelsbetter the faster you go. Still there's that feeling you get in thecompany of pit bulls you don't know well, or from people you meetin jail.

I have a vague comprehension that someone who knows what he'sdoing could make serious, tire-spinning time on this monster, butthat rider would possess huge skill and reproductive organs alsonot to scale. (Maybe that's why the seat's so high?) It's a500-pound object, dear, and while its limit is a ways out there,you'd eventually grow familiar enough to explore the perimeter. Youjust know that when you step over the line with this bike,gathering things back up could be like attempting to shovetoothpaste back in the tube at a very high rate of speed whilewearing thick gloves. All the power in this bike reminds us of theold saying about rain tires: They simply allow you to crash at ahigher rate of speed.

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

• Yosh. Stage One billet
camshafts $700
• Yosh. Standard bore
12.5:1 piston kit $1200
• Carrillo 4340 steel
connecting rods $1000
• Falicon lightened crankshaft call
• Yosh. High exit titanium
exhaust, Tri-Oval muffler $1825
• Yosh. Light porting,
intake and exhaust call
• NGK surface gap spark plugs $29 ea.
• MoTeC M48 programmable
sequential engine controller
with custom harness $4600
• MoTeC ADL dash/logger
with custom harness $6000
• Öhlins superbike fork $7000
• Yosh. kit magnesium triple
clamps, 30mm offset $2500
• Öhlins superbike rear shock $1100
• Yosh. linkage $450
• GSX-R750 superbike quick-change swingarm/rear brake $5500
* Marchesini kit magnesium
wheels $3000
* Six-piston AP monoblock calipers with 320mm cast-ironrotors $2000
* Brembo brake and clutch
master cylinders $400 ea.
* Yosh. two-piece clip-ons $225
* Yosh. rearset footpegs $440
* Yosh. Tornado 24L endurance fuel tank/superbike fuelpump $2900
* Yosh. Tornado body work $2500
* Yosh. radiator (TL1000R superbike top, GSX-R750superbike
bottom $7000
• Earl’s cylinder head oil cooler $50
(paint by Boris at California Design)  

Turbo 'Busa

If you think northern Sweden is no place to base a motorcycletuning firm, Erik Marklund of MC Xpress would disagree. “Becauseit's so cold and dark almost all the day in winter, we have plentyof time to work on the bikes,” he says. “And in the summer it'slight almost all the time and often hot. We have some nice straightroads with not many people or cars or police, so it's great forriding fast.”

Erik has built a string of ultrapowerful specials since foundingMC Xpress 10 years ago-turbo kits for sportbikes being the housespecial. He sold around 100 turbo kits all over the world lastyear. His latest and most outrageous project: the turboHayabusa.

The effort to cram the turbo into the very compact 'Busa wasworthwhile. 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 thestandard claimed max of 173 hp-and kicks out more than the stockSuzuki everywhere above 6000 rpm. Weighing little more than thestandard bike, the big blown 'Busa has an almost identicalpower-to-weight ratio as Honda's NSR500 works GP bike.

The Mitsubishi turbo, used in some Volvo cars, is particularlysuitable due to its built-in “pop-off” valve. “When a normal turbois boosting and you close the throttle, the air has nowhere to goand produces a big pulse,” Erik says. “This can destroy the hosesand intercooler and also means the turbo stops running, so if youopen the throttle again you have no boost.” Normally a separatevalve is used to prevent this, but it's unnecessary with theMitsubishi design.

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

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

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

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


American Turbo Systems

3435 Enterprise Ave. #50

Naples, FL 34104

Tel/fax (941) 403-0198


Yoshimura X1

MSRP How much you got?
Type liquid-cooled inline-four
Valve arrangement dohc, 16v
Displacement 1298cc
Transmission 6-speed
Weight (claimed) 485 lb. (wet)
  447 lb. (fuel tank empty)
Fuel capacity 6.3 gal. (24L)
Wheelbase 57.5 in. (1460mm)
Seat height 34.0 in. (864mm)

  • Yoshimura Suzuki Hayabusa X 1 Side View

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