Cycle News - Archive Issues - 1990's

FIRST RIDE Hunwick Hallam X1RSuperbike. 24 any trace of that kind of engine speed, or performance, in the form I actually rode on the phase-one bike at Eastern Creek. In steeI-engine guise, the XIR feels to have a similar level of performance to a Ducati 955SP: Impressive but not earthshattering in superbike terms, though still a good starting point. It feels like a very fast road bike, with more midrange than you'd ever really need-:' a feeling confirmed by the five-speed gearbox off the Boss Power Cruiser fitted to this ground-zero version of the engine (used in the rush to get it ready for the Phillip Island demo, when the six-speed race cluster still wasn't ready). The bottom two gears in the five-speeder are too low for race-track use, though no doubt ideal for boulevarding and cruising the strip. Basically, the steel engine feels like a downsized race version of the Power Cruiser motor, which, considering that's probably how it started out in the HH development cycle, isn't so surprising. If my debut test of the 1-Iunwick 1-Iallam X1R had been confined to this particular bike, I'd have concluded that here were the makings of a very fine supersport street tooi, on which some hard work was needed to turn it into a competitive racer. But the thing is, that hard work's already been done! After a couple of sessions totaling 20 laps or so on the phaseone bike, they called Mal in and gave me the keys to the phase-three version. Wow! Who'd have thought there could be such a big difference between the two? Whereas the steel-engine bike is slower and more punchy in its pickup, the phase-three titanium engine - fitted with the six-speed gearbox that will be standard on the XIR road bikes - has an appetite for revs and a throttle response that is dramatically enhanced. You'd swear from riding the two bikes back to back that they had different cam profiles and fuel-injection mapping - bu t Paul Hallam insists this isn't so. "We needed to get a direct comparison by changing only one set of parameters at a time," he says. "The two engines are essentially identical, apart from the gea~box, even down to the same 11.8:1 compression ratio and choice of engine map - we don't alter management settings via EPROM chips but via a plug-in connector to a laptop computer, and I've just pressed the same button twice for each bike. It's a dramatic confirmation of how much power can be unlocked by reducing the inertia of the bits that go up and down inside the engine." I'll say! I've never before had a direct comparison between the same engine with titanium and steel internals, but my experience with the Hunwick Hallam has made me a believer: As ~oon as I got off the plane from Oz, I checked my bank balance and ordered a titanium conrod and valves for the Supermono. It's the snap from the engine that's most noticeable, the way that engine speed picks up so much faster from low down, translating in turn to vivid acceleration out of turns or down the Eastern Creek front straight, where the pickup from the steel engine had been more measured by comparison. Yet this enhanced engine response hasn't been obtained at the cost of that excellent midrange torque, which is still as strong as before - only that because the engine picks up speed faster, you're forced to use .the gearbox more to keep the motor dialed in higher up, where there's definitely more power available. This phase-three motor also felt smoother and better balanced than the older version, with less vibration and not as harsh a feel when revving hard obviously a function of the different balance factor obtained with the lighter internals. The throttle has a very precise feel from the light-action EFI butterflies HH makes its own fuel-injection system, including the 55mm throt·tle bodies, with software and ECU developed in conjunction with Australian EFI specialists Motec, but using a sin'gle Bosch injector per cylinder, located aft of the butterfly. Hallam says the 4 bhp gained by using the secondary injector originally located at the entrance to the throttle venturi didn't justify the extra weight and complication, though he may return to it later. In terms of weight, the titanium phase-three bike already shows the fruits of development, scaling 369.6 pounds half-dry, against the steel engine's 380.6 - another reason for the improved acceleration. In this form, the HH Xl R. has taken a definite step up the performance ladder - a fact immediately confirmed by the lap times. In phase-three form, I'd say the bike is roughly equivalent to a '96 Ducati 955 Corsa customer racer, or, in other words, essentially the same as the bike that Carl Fogarty last used to win the World Superbike title back in '95. It's even got the same ratio of torquey midrange to power-up top end - though I think that, like Ducati did between the '95 and '96 seasons on its works bikes, the HH team still needs to work on improving engine breathing on the race track in terms of shape and flow to the airbox, to get the high revs they need to obtain that impressive power figure achieved on the testbed, which Paul Hallam says he's confident is a realworld output, not a flash reading on a friendly dyno. At the moment, it doesn't feel.as if even the titanium motor is putting this kind of power to the road - but certainly the Xl R is heading in the right direction. For a motorcycle to deliver this kind of performance so early in its R&D cycle promises great things - and Mal Campbell, not noted for being easily impressed, agrees. "I reckon they've coine a long way in a relatively short time," he says. 'There's lots of refinements to be made, just as you'd e~pect from an all-new design, but the basic package is there, and it'll be a very good motorcycle very soon." In a way, the most surprising thing is that not only is the engine so potent up front, but that HH has scored a hole in one with their innovative chassis design, too. The cast-alloy spine beam from which the WP upside-down forks are hung forms the basis of the design, with the engine forming an integral part of the chassis. The conventional (not single-sided) swingarm pivots in the crankcases, Ducati-style. Like on the Britten and another Aussie bike, the Ducati-powered Vee Two Alchemy, the rear shock is located off to the side and up front, so as to increase the front-end weight bias and leave space for the spaghetti nest of exhausts to exit cleanly. On the XIR, the WP shock (presently fitted with an OhIins spring, after the team'discovered it needed far softer suspension settings than comparative Vtwins) is operated by an ingenious system using an alloy rod with a rising-rate linkage at one end. The result steers very well and has excellent ride quality thanks to the lower spring rates, making" the suspension more compliant ov.er bumps and ripples such as abound at the Creek - though on the pec-one bike, it was too soft for my extra weight, compared to Mal's. The resulting windup out of turns could be easily dialed out with a stiffer spring, though, I'm sure. But the compliant suspension meant neither bike shook its head if you hit a bump or ripple cranked over, and it was very stable under power - no pushing the fron.t end accelerating onto the Creek's front straight, as many bikes with inherent power understeer do. The basic design has very neutral, poised steering. However, this earlier bike also had a slightly steeper head (Above left) Though still not fitted with pneumatic valve "springs," the phasethree engine has been uprated significantly since the first-generation powerplant, principally through the extensive use of titanium for int4!mal components. (Above) As one expects from a V-twin, the Xl R is quite narrow, barely wider than its 6-inch-wide rear tire. angle at 23 degrees vs. 23.5 (easily changed with the cartridge design for the chassis spine, using different attachment points to the engine), a 25mmshorter swingarm setting than the newer machine (also readily adjustable without having to cut 'n' shut a new unit), but with the rear ride height raised to deliver the same 53/47 percent weight distribution, rather than the greater rear bias tha t the shorter swingarm would normally deliver. . All this made changing direction quickly in some of the Creek's tighter turns notably better than on the specthree bike, without sacrificing traction. And though I can't truthfully say I rode the XIR at racing speeds yet, I certainly rode plenty hard enough to be impressed - astonished, even - with the handling package. . Getting the engine to its present level of performance is one thing - hours spent on the dyno eventually have their just reward. But for someone like Paul Hallam, who never built a motorcycle chassis before, to get the Xl R handling so well straight out of the box is a genuine achievement, and augurs well for the development of the street version, too. In fact, there's no getting away from it: Hunwick Hallam has delivered the goods, not only on paper but in realworld riding conditions Where there are no secrets, only truth. Now we must wait to see how the XI~ stacks up against the superbike establishment in hard competition - but my bet is we're looking at a serious new addition to four-stroke racing's lineup of contenders. And what wins on the race track sells in the showroom. ~

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