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SR Archive: Riding Aaron Slight’s Honda RC45 World Superbike Racer

Photography by Kevin Wing

“Aaron Slight’s Castrol Hinda World Superbike is one snarling, hard-hitting animal of a bike.”

This article was originally featured in the August 1995 issue of Sport Rider

The deep growl emanating through the sewer pipe–diameter ram-air intakes poking out either side of the RC45’s short, wide gas tank echoed through my Arai helmet, serving notice that Aaron Slight’s Castrol Honda World Superbike is one snarling, hard-hitting beast of a bike. After five fleeting laps on an RS125 to learn the course, I’m rolling out of Suzuka’s pit exit heading into decreasing-radius turn one thinking this is one machine that demands respect.

Here at Suzuka in particular, Honda’s RVF750 RC45 (as it’s officially known) commands the respect befitting the winner of the Suzuka 8-hour, a race which imparts more bragging rights to its winner than any other single motorcycle competition event in Japan—perhaps the world. The Suzuka-winning RC45, ridden by Aaron Slight and teammate Doug Polen, differs only minutely from the WSC sprint bike we rode with its increased fuel capacity, an electrical system capable of powering a headlight, a steel (rather than titanium) exhaust system, a 25mm-longer swingarm and quick-change wheel systems. The changes added just over 10 pounds to the sprint machine, yet it was potent enough that Slight outran a hard-charging Kawasaki ZX-7R-mounted Scott Russell in the final hour of the race.

We got to take a spin around Suzuka on Aaron Slight's RC45 World Superbike Racer.

Photography by Kevin Wing

We got to take a spin around Suzuka on Aaron Slight’s RC45 World Superbike Racer.

It seems especially fitting to ride Honda’s premier four-stroke at the very venue in which it had its greatest success. Like the stock RC45, Slight’s machine has peculiar ergonomics that splay the rider’s arms and legs around its wide fuel tank. I feel like a monkey hugging a beach ball. Ergonomic concerns fade as soon as I tip the bike into turn one. The Honda’s wide bars afford a lot of leverage which, when combined with the steep 22.5 degrees of steering-head rake, allows the bike to tip in with startling ease and an unnerving lack of front-end feedback. It feels like power-assisted steering that robs feel—something I’m sure would improve with familiarity, which my six laps don’t allow. (Each journalist was to get a maximum of five laps before being flagged in, but swept away in all the excitement I didn’t see the Japanese man frantically waving at me—honest.)

Honda’s 90-degree V-four is wrapped tightly within the RC45’s twin-spar aluminum frame, making it one of the the most time-consuming engines to service and maintain. Slight’s bike uses a titanium 4-in

Photography by Kevin Wing

Honda’s 90-degree V-four is wrapped tightly within the RC45’s twin-spar aluminum frame, making it one of the the most time-consuming engines to service and maintain. Slight’s bike uses a titanium 4-into-2-into-1 exhaust system.

Twisting the low-effort throttle hard out of the esses, the torquey V-four astounds me with its quick, clean throttle response and the strength with which it pulls from as little as 7000 rpm. (It may not sound like it, but 7000 is low rpm on a Superbike). The Honda’s engine produces what feels like a flat-as-Kansas torque curve, which builds horsepower in a perfectly linear relation to increased rpm with none of the peakiness prominent in its in-line four competitors. This makes for an eminently ridable street engine, but when combined with the fuel injection’s somewhat digital throttle response it can limit how early in the corner the rider is comfortable getting into the throttle and starting the drive.

I’ve heard that although Slight’s machine equalled the competition’s 181-mph trap speed at Hockenheim, it lacks acceleration. From my limited experience testing AMA Superbikes and WERA F-USA machines, Slight’s bike accelerates god-awful hard up to just short of its 14,500-rpm rev limit in all six gears. It makes me nervous holding the throttle open past the first brake markers going into the chicane and turn one, and wondering how much faster the 500 GP bike could be. Much faster, I would find out later in the day.

Related:

Hidden behind carbon-fiber heat shrouds are a pair of Brembo 320mm carbon/carbon rotors, banned from WSC and AMA competition after last season. While the lighter NSR500 and NSR250 make do with smaller

Photography by Kevin Wing

Hidden behind carbon-fiber heat shrouds are a pair of Brembo 320mm carbon/carbon rotors, banned from WSC and AMA competition after last season. While the lighter NSR500 and NSR250 make do with smaller 290mm discs, the RC45 uses the larger rotors. There was no shortage of stopping power, although modulation was different from what we’re accustomed to with metal brakes.

The huge Brembo carbon brakes took a bit of getting used to. They come up to temperature surprisingly quickly, which is good since carbon brakes offer little to no stopping power until they’re warm, but even the excellent Brembos give softer, less direct feedback and modulation than the metal brakes I’m more familiar with. Since carbon brakes are more effective at higher temperatures, they don’t fade the way metal brakes are prone to do. Instead they scrub speed at an increasing rate as you hold constant lever pressure; it’s disconcerting at first, but it also gives the feeling of unlimited stopping power. Perhaps their biggest advantage is their reduced rotating mass and resulting gyroscopic effect, which makes the bike much easier to flick side to side.

Everything about Slight’s machine, from its throttle and braking effort to its handling and steering characteristics, feels overwhelmingly light, but with that light feel comes an insulated detachment from what’s happening. The front end in particular feels light on the pavement, never inspiring the confidence to flick it as quick as the effortless steering would allow. Compared to a few of the better Kawasaki, Suzuki and Yamaha AMA Superbikes I’ve ridden, the Honda feels numb and isolated from what’s going on with the engine and tire contact patches. Perhaps not so strangely, the stock RC45 street bike exhibits many of the same traits.

Honda’s PGM-F1 fuel injection has a control box mounted inside the fairing nose that adjusts air/fuel mixture plus or minus 20 percent. The four adjustment knobs correlate to throttle openings of zero

Photography by Kevin Wing

Honda’s PGM-F1 fuel injection has a control box mounted inside the fairing nose that adjusts air/fuel mixture plus or minus 20 percent. The four adjustment knobs correlate to throttle openings of zero to 25 percent, 25 to 50 percent, 50 to 75 percent and 75 to 100 percent, respectively.

It’s unlikely that a journalist with six brief laps is going to uncover anything of much significance for the HRC crew, but it is interesting to hear that the Castrol Honda team has spent so much time fiddling with chassis geometry and frame bracing. It’s also interesting to see that the RC45 doesn’t feature an adjustable swingarm pivot as seen on the Kawasaki ZX-7R and Yamaha YZF750SP. Moving the pivot point changes how the swingarm reacts to the drive-chain forces under acceleration, which in turn has a major effect on rear-tire traction. It’s puzzling why Honda would give up such a potentially useful tool. It will be interesting to see what changes have been made for this season.

As much as the Suzuka win meant to Honda, it was the RC45’s sole victory in international competition last season. And it wasn’t for lack of effort. Most race watchers would agree that the ever-aggressive Slight rode on and over the edge more often than either Russell or Fogarty, yet his best finish was second—a position he repeated eight times in 22 races last year. That’s good enough to earn the New Zealander third in the ’94 World Superbike Championship, but Honda didn’t design the RC45 to finish third—or even second. As evidenced by RC45 Development Engineer Mr. Ono’s eagerness to ask even us journalists our feedback and suggestions the day we rode the bike, Honda is hard at work to better those results for this season. If the recent AMA Superbike win claimed by Smokin’ Joe’s Mike Hale and his Merlyn Plumlee-tuned RC45 is any indication, Ono-san and the HRC crew spent their off-season productively.

Stripped of its carbon-fiber bodywork, the Castrol Honda RC45 displays a few of the parts which make it the most technically sophisticated and expensive Superbike on the circuit.

Photography by Kevin Wing

Stripped of its carbon-fiber bodywork, the Castrol Honda RC45 displays a few of the parts which make it the most technically sophisticated and expensive Superbike on the circuit.

Temp Gauge:

High Low

Linear horsepower delivery, flat torque curve and immediate throttle response
All that technology carries a frightening price tag

Fast enough in Suzuka 8-Hour trim to fend off Scott Russell’s Kawasaki and claim the win
Chassis lacks the balanced and connected feel of its better rivals

Bristling with technology as only a Honda can
Fuel-injection computer and other exotic parts are difficult for privateer teams to obtain or fabricate

More articles in the SR Archive.