Kawasaki Zx-10r

KAWASAKI ZX-10R

NEW BIKES 2008

More power, higher performance, a new chassis and...traction control!

MARK HOYER

SUBTLETY HAS NEVER BEEN THE KAWASAKI ZX-10R's GAME. In fact, the term brutally fast" was redefined by past versions of this motorcycle. And while the 2008 model does take the big electronic leap to traction control to help tame the savage beast, every other aspect of the bike has also been redesigned with controllability in mind.

The engine, for instance, is more powerful (no numbers released) yet it also has more linear, and therefore more predictable, delivery. The frame and swingarm have been completely changed, their new design focused on offering greater feedback. Even the seat and bodywork have been given contours to allow the greatest amount of interface with the rider so that the machinery transmits as much information as possible to the person guiding it.

CW EXCLUSIVE

Kawasaki was clear that development of the bike was oriented toward racing, that those things found to work best on the track were then tried on the street, refined and tried on the track again so that the all-out performance focus wasn’t lost.

First things first, though. Sportbike manufacturers have been successfully experimenting with traction control for some time now in their MotoGP and Superbike racing efforts. But Kawasaki gets the nod for being the first to announce that such a system will be available on a 2008 supersport production motorcycle-although the company’s legal department has insisted that rather than “traction control” it be called an “ignition management system.”

“On to the mystery component,” said Kawasaki’s lead tech guy, Rob Taylor, who gave us a rundown of the setup. “It is going to sound like Big Daddy trying to keep you from doing a burnout, but it is about regaining traction, in corners, in places where you are inclined to slip.”

Wheelspin gets the black box’s attention when it detects a significant, sudden spike in engine rpm, as when the rear wheel breaks loose under power.

If revs rise too quickly, the ECU intervenes by retarding ignition timing to reduce power output. As noted, primary indication that intervening action is necessary comes from engine rpm (there are no wheel-speed sensors), but this rev spike actually only triggers the system to read data from other sensors that record gear position, throttle position and vehicle speed, before action is taken.

Why? Say, for example, you are slipping the clutch and revving the crap out of the motor on a hard launch. Sudden spike in rpm, yes, but this is no time to take power away! You’ll lose the race. By monitoring what the output side (the speed sensor is in the transmission, after the clutch) is doing, the system knows if the rise in engine rpm is actually resulting in an equally quick rise in wheel speed (i.e. “spin”) or if it should just let you merrily fry the clutch plates. Neat.

Taylor also explained that the system doesn’t work at “zero ground speed” (say hello to smoky burnouts) or at wide-open throttle, because when you are asking for everything she’s got, you should have it. Just make sure you’re ready for it...

This naturally leads to the fact that horsepower on the 998cc inline-Four has been increased. Official figures hadn’t been released as of this writing, and it will be quite a while (bikes go on sale in January for $11,549) before we get a new 10R on the dyno. But we have seen about 160 horsepower at the rear wheel from lORs pretty consistently over the past couple of years, and Suzuki’s superb 2007 GSX-R1000 showed 163 horses on our dyno. If we give Kawasaki a reasonable 5 percent bump over its past efforts, 168 hp at the rear wheel is conceivable.

Although our prurient interests always seem to focus on peak horsepower, Kawasaki worked on improving the ZX-10R’s midrange, too, eliminating a dip in the torque curve of the previous bike. The basic architecture of the engine remains as it was in 2007, but there is a long list of new parts and new castings.

Starting at the top, cams are cut from forged chrome-moly billets, making them about a half-pound lighter than the ones they replace. New lobe profiles produce more lift and increase duration. As ever, sprockets have slots for cam-timing tuning. The intake ports were reshaped and reground, again, to improve high-rpm breathing.

“These are hand-ground ports,” points out Taylor. “The ZX-6R is the same, and now we’re doing it on the 1000.” Who does this work? “There is a row of ladies, actually, on the assembly line in the Akashi factory (Kawasaki’s bike-making HQ), who grind all the ports,” he replies.

Exhaust valve sizes have been reduced from 25.5 to 24.5mm. The ports are narrower at the midpoint and larger at the exit to improve exhaust flow, and work with new steppeddiameter titanium headers to improve extraction. The combustion chamber’s shape was altered to match the new angles of the seat area, due to the valve-diameter change.

The tachometer on the early production bike we photographed shows a 13,000-rpm redline, same as last year, although there was discussion in our tech briefing about the power peak being raised from 11,500 to 12,500 revs. In any case, single, oval-wire valve springs are used because the narrower vertical cross-section allows the springs to be more squat. “This lets us lower the height of the cylinder head,” says Taylor. “We’ve been doing this for a while.”

New forged, sintered-aluminum spring retainers halve the weight of steel retainers and allow for safer highrpm running. This may simply allow the ZX to run the more aggressive cam profiles at the same max rpm as last year without losing valve control.

Crankshaft weight is reduced by 2 pounds. Benefits of this are multiple. Of course the engine can rev more quickly. But it can also be decelerated with less effort and stress because of the reduced inertia. The lighter crank and lower ratios in first, fourth and fifth gears (to suit the new power curve) led to a different setup on the slipper clutch. Optional spring retainers and shims will be available to fine-tune the slipper action to your liking. The rear sprocket is one tooth larger.

As with earlier models, upper crankcase and cylinder are a one-piece casting. “We are using the engine more and more as a stressed member,” says Taylor. “Any time you put a gasket in, you’ve got motion, flex.”

Engine castings are made using a new process called “slanted casting,” in which the pieces are rotated during the process, resulting in a more-dense piece with fewer imperfections.

“This casting method makes very smooth internal passageways,” claims Taylor. “Oil galleries are smoother, which means the oil pump doesn’t work as hard and the engine is more efficient. This helps the engine as a total package. People concentrate on the outside of the engine and its smoothness, but inside is what counts.”

That shows a refined thinking in design and manufacturing terms, also hinted at in parts of the stacked gearbox. Specifically, the transmission gears are made with the smallest diameter possible. “This saves weight, yes,” says Taylor, “but the real benefit is that it creates very smooth shifting because the surface speed of the dogs is lower, so they match more easily at high rpm.”

Imagine how much faster the tire is moving than the wheel is just one inch from the axle. Rpm for the two points is the same, but the distance traveled -(and therefore speed) is significantly lower closer to the hub, just as it would be on a rotating gear closer to its hub. As we see more and more, emissions is a big driver of powerplant design. The ZX-10R engine is efficient and clean enough that it gets away without using an O2 sensor and has freer-flowing 200cell exhaust catalysts, rather than the denser, more restrictive 300-cell units used by some other manufacturers.

But the exhaust is only part of the overall system of making big power with clean emissions. This year, the 43mm Keihin throttle bodies have ECUcontrolled sub-throttles. “Our ports are so big these days, we need to regulate the intake pressure for more linear power,” says Taylor. The throttle bodies themselves are now oval in shape, making them more narrow to fit the more compact overall size of the bike but also because, reveals Taylor, “Changing the ‘shape’ of the air makes the charge more dense in some areas to increase its energy.” This leads to improved cylinder filling.

The EFI system now uses two injectors per cylinder. At low engine speeds, ultra-fine-atomizing main injectors allow very precise fuel control and a good spray pattern at the low volumes encountered at smaller throttle openings, while the secondary showerhead injectors are farther away from the intake valves (giving time for the fuel to mix more completely with the intake charge) and deliver the extra fuel necessary for top-end power. The switchover point when the secondaries are activated is predominantly controlled by rpm. “We can finely tailor low-rpm injector output for better rideability and lower emissions,” says Taylor.

The overall induction-system volume is considerably smaller than it was in the past. The new box was flow-tested with a manometer, and the path from the fairing air inlet to the intake valve is now shorter and straighten This led to two results, one expected, the other surprising.

“Any time you shorten the intake tract, the harder time you have with fluids,” remarks Taylor. “Riding in the rain can basically soak the air-filter and choke the engine. So we flowed the box and other parts to make the design remove water from the intake tract. But the way we do the channeling to control the water also controls the sound, the harmonics of the intake tract, to keep it quieter. This is why we could make the induction system smaller, and in turn make the bike smaller.”

An added benefit is that the 4.5-gallon fuel tank can be lower, dropping the center of gravity and giving the rider more room to tuck in behind the new fairing’s decreased frontal area.

All of the above is good news for acceleration junkies. Think of wheelspin management, shorter gearing, increased power, lighter, quicker-accelerating engine internals and the positive effect all of this is likely to have on quartermile times. But while the 10R is sure to be quick at the strip, most of us know cornering is where the real fun is.

To put the handling character into perspective, several years ago a certain quick-riding Road Test Editor did a very fast lap on a ZX-1 OR, the fastest of the day-scary fast-after which he said, “I sure hope I don’t have to go for that time again!” The 10R has always been extremely quick but demanded a lot of respect and attention.

“We have concentrated on making the package more useable by the rider,” says Taylor of the lOR’s new chassis and swingarm. “The primary focus was on chassis feedback.”

“Stiffness balance” has become a buzz phrase, and Kawasaki uses it in regard to the 1 OR. “What we mean is we’ve worked on the balance between how rigid and how forgiving in motion the chassis is. We have gone out of the way to make parts that transmit accurate ‘bending’ feel to the rider,” he explains.

Designers reshaped pressed alloy parts such as the main frame spars, plus used convex pieces instead of concave in certain areas, all in an effort to allow the frame to bend here, not there. Places where stress was concentrated were relieved by using different materials and shapes. “Stress areas eat transmission of feedback,” Taylor says. “They hog up any kind of motion as feedback. By changing parts and process, we’ve made the frame more friendly to the transmission of these motions.”

The same goes for the longer braced swingarm that rides in a relocated, beefed-up pivot area. Further, the engine has been repositioned in the frame for mass centralization and better roll response.

“Main focus was handling and the ability to race the bike,” says Taylor. “Anybody who seriously races knows feedback is the most important thing. The ability to feel a vibration and sense what the tires are doing. The ZX1 OR has always had behemoth power but now we’re putting it to the ground better.”

Diamond-Like-Carbon is applied to the 43mm inverted fork tubes for reduced stiction and, you guessed it, better feel. The KYB unit now features the “upsidedown” cartridge that reduces oil aeration and stabilizes damping characteristics. This moves the springs to the bottom of the fork. KYB also makes the shock, and it now features highland low-speed compression-damping adjustments to go with the threaded spring-preload collar, rebound-damping and shimmed ride-height tuneability. Front and rear suspension units feature top-out springs.

Styling echoes Kawasaki’s MotoGP bike, with aggressive forward slants to everything, even the fuel tank top, and a high, short, pointed tailsection. The lines of this bike, like many of Kawasaki’s recent offerings (ZX-6R, Concours and ZX-14, the original Z1000), get their start in a one-man studio in Japan, off factory premises. An ex-Mazda guy, the designer gets handed the model “concept” as initial guidance and is informed by the heritage of the bike and company, then shuts the door and works solo carving several styling bucks for review.

Not that the man’s designs are chiseled in stone, unassailable. One of the leading styling studies for this bike had a fairing front with the center black plastic section formed as a pair of rounded mounds bifurcated by, shall we say, a crack similar to that of a person’s posterior anatomy. People in product planning tried to politely say that this wasn’t really what they wanted but to no avail. Finally, somebody wrote, “Butt-face has to go,” on the board. Ta da!

Anyway, the gaping chasm at the front is the air inlet, while the fairing top is shorter and features a flatter-mounted windscreen.

Ducts at the front of the cowling lower reduce windblast to the rider by keeping airflow at the bottom of the bike laminar; in this way, turbulence doesn’t swirl up the sides of the bike and enter the still pocket behind the screen. Compared to the more organic 2007 fairing, the ’08’s smaller side area should reduce the influence of crosswinds, too.

While the styling is pretty cool, it’s what’s inside that counts. There is plenty left to find out about the new ZX10R, especially its use of active engine management to control rear-wheel spin. This is technological trickle-down at its best, with the potential of making high-performance motorcycles easier to control, offering better performance more of us can access. Here’s to the future of brute force with brains.