2008 Honda CBR1000RR - Light Makes Right
photographer: Kevin Wing
The past few years have seen a distressing trend in sportbike design, as most models are getting heavier with each update. Earlier in the decade when titanium became more cost-effective and before emissions standards were tightened up, sportbikes were scaling in at record minimums each year. Since then, however, each new model seems to be heavier than the last. It's easy to see how this can happen: A stronger engine and stickier tires require a beefier chassis for similar handling characteristics. More power calls for a larger radiator and a more complex cooling system to keep temperatures in check. Stricter emissions laws make catalytic converters mandatory. And additional sensors, servomotors and wiring become necessary to keep all that power usable.
One manufacturer that has bucked the trend of increased weight in recent years is Honda. While the first-generation CBR1000RR and CBR600RR were considerably heavier than their competitors (and their predecessors), both have slimmed down progressively with each iteration. Last year the third-generation middleweight CBR-now one of the lightest bikes in the class-dominated our comparison test and almost knocked the mighty GSX-R1000 off its Bike of the Year throne. Like its middleweight sibling, Honda's literbike lost 15 pounds in its first update in 2006, and this new '08 model according to company reps has lost 17 more pounds. That would put the CBR1000RR at 435 pounds wet, significantly lighter than the other bikes in the class and on par with the flyweight ZX-10R of a few years ago. This is a good thing.
Improving power-to-weight ratio was one of Honda's design goals for the '08 1000; the others were to use race-proven technology (such as the electronic steering damper and Unit Pro-Link rear suspension) and to create additional new technologies. Those new technologies include the Ignition Interrupt Control System, which smoothes the off/on throttle transition by detecting driveline lash and cutting power momentarily. The setup is significantly different from Kawasaki's Ignition Management System and not a form of traction control, but it addresses an important part of driveability. See the sidebar on page 44 for more details and the tech sidebar on page 40 for more information about the CBR's other updates.
The new model was introduced at Mazda Raceway Laguna Seca, with journalists spending a day on the track in sunny and cool conditions. Trust Honda to pamper the journalists: A row of bikes sat ready, their OEM-spec Dunlop Qualifiers coddled in tire warmers, with mechanics standing by to make adjustments and my name on one bike's windscreen. Just looking at the old and new CBRs beside each other shows how trimmed-down the new bike is. A tiny tailsection replaces the old underseat exhaust, tidying up the rear end. The foreshortened front fairing gives the whole bike a stubby, bulldog look, and the underengine exhaust is quite small compared with how it appears in pictures. Sit on the new bike and its diminutive size is even more apparent: The clip-ons are slightly higher and closer to the thankfully softer seat, the windscreen and fairing are narrower and even the gauge package is smaller.
A short presentation in which the Men in Red discussed the CBR1000RR like proud new fathers and we were set loose on the track. Does all the weight-saving pay off when it comes to riding at Laguna? It took just a couple of laps to find that the new CBR steers easier and transitions quicker from side to side than its predecessor-and just plain feels lighter and smaller. The counterbalanced mill is quite smooth on the track and, with the quieter exhaust tucked underneath, sounds and behaves even more refined. Honda had a few '07 models on hand at Laguna, and a short ride showed that at very low speeds-like exiting the pits or transitioning at the top of the Corkscrew-the old bike's steering is just as light as the new bike's. Farther down the track in the run to the start/finish straight, though, the new CBR puts its predecessor to shame, arcing from full lean to full lean noticeably easier at higher speeds.
Entering turn 11, the slowest on the track, requires downshifting to first gear on both bikes, and it's here that the new slipper clutch comes in handy. While the old bike had to be downshifted with drill-sergeant precision and perfectly matched revs to avoid chatter from the rear wheel, the '08 offers much more leeway and allows you to be lazy on downshifts or divebomb a corner progressively deeper with the added confidence of knowing the rear wheel will stay in line. The other two pieces of the rider-control puzzle, the Idle Air Control Valve and Ignition Interrupt Control System, go a long way toward reducing engine braking and smoothing the off/on throttle transition. At very low rpm-trolling the pits or on an out lap-fueling is still somewhat abrupt, but everywhere else, whether in the IICS's working range of 2500-6000 rpm or higher, response is silky smooth.
The new one-piece front Tokico calipers certainly offer more braking power with less effort, but their initial bite is better described as a nibble, and it's only until well into a braking zone that their full performance is realized. The soft lever requires a strong pull for good initial stopping power, yet the very progressive action ramps that up quickly and forces you to ease off significantly to avoid locking the wheel. I briefly quizzed Kyoichi Yoshii, Large Project Leader for the 1000, about it, and he pointed out that the design reduces the grabby feel normally associated with big brakes without sacrificing overall power. I can see this paying off on the street, but for track work I prefer the more linear action of the old bike's stoppers.
The old bike's excellent dash has been replaced with a smaller, tidier layout that shows more information, including fuel-mileage numbers. Redline is up from 12,200 rpm to 13,000 rpm.
Surprisingly, acceleration off the slower corners felt similar between the two models, and this brings to light some interesting details omitted from the press material. While final gearing is unchanged and primary gearing has been shortened, the internal ratios have been closed up significantly; overall gearing ends up being taller in the lower gears, shorter in the higher gears. Stretch out the powerband the additional 800 rpm that the new bike revs, and the '08 model could very well have less thrust at the rear wheel than the old bike in the lower gears. The previous models-both generations-had widely spaced gearbox ratios that made them quite a bit peppier (and more fun) than their rivals on tighter roads, and hopefully that aspect has not been lost with the new transmission. It all pays off when you give the '08 model some room to stretch its legs, however, and the combination of more power, less weight and closer ratios in the tranny provides an undeniable advantage.
Interestingly the use of Qualifiers marks the first time since the original CBR900RR that Dunlops have been fitted as OEM equipment to a literbike CBR. About half the 1000s imported will be shod with the Dunlops, the other half with Bridgestones. While the rear Qualifier sticks like flypaper to Laguna's pavement even under the brutal acceleration the CBR offers, the front Qualifier-as we've experienced with other OEM variants of the same tire-is a bit numb on front-end feedback at full lean. For the afternoon sessions the bikes were fitted with Dunlop's new D211 GP race tires, which feature the company's N-Tec construction and a dual-compound rear tread. Mounting the huge-diameter rear tires (stock on the CBR is a 190/50; most race tires are 55 series) significantly changes gearing. On the original '04 1000 that definitely hurt performance, and the '06 second-generation 1000 was less, but still noticeably, affected. The new CBR didn't seem to be bothered at all with the swap in rubber, accelerating with the same immediacy in the same gears from each of Laguna's turns.
The increased grip and feedback from the DOT front race tire and the additional rear ride height from the tall rear tire quickened steering even more than with the stock tires, and the big CBR absolutely railed into Laguna's fast sweepers leading down the hill from the Corkscrew. In fact at the end of the day I thought the CBR rivaled Yamaha's YZF-R6-which I had ridden at the same track a month earlier-for front-end performance. Impressive, yes, but keep in mind the R6 introduction was conducted entirely on the stock Qualifiers. Keep in mind, too, that the Honda is just seven pounds heavier than the R6.
Overall the new CBR1000RR is an impressive piece, raising the bar for user-friendliness and handling in the class. In addition to facing the current class king, the unchanged GSX-R1000, the Honda has an all-new ZX-10R and the R1 (which should benefit from an upgraded ECU for this year) to deal with for literbike honors. We've got a date at Buttonwillow Raceway and a stack of Dunlop D211 GPs standing by for this year's shootout, and we'll soon see how the Honda stacks up against the competition.
'08 Honda CBR1000RR
MSRP: $11,599 ($11,799 in black/metallic gray)
Engine
Type: Liquid-cooled, DOHC, transverse-four, 4 valves/cyl.
Displacement: 999cc
Bore x stroke: 76 x 55.1mm
Compression ratio: 12.3:1
Induction: DSFI, 46mm throttle bodies, 2 injectors/cyl.
Chassis
Front tire: 120/70ZR-17 Dunlop Sportmax Qualifier PT K
Rear tire: 190/50ZR-17 Dunlop Sportmax Qualifier NK
Rake/trail: 23.3 deg./3.8 in. (96mm)
Wheelbase: 55.4 in. (1407mm)
Seat height: 32.3 in. (820mm)
Fuel capacity: 4.7 gal. (18L)
Claimed dry weight: NA
Claimed wet weight: 435 lb. (197kg)
CBR1000RR Tech
 Central to the CBR1000RR's redesign is a five-pounds lighter, more compact engine with a 1mm-larger bore and correspondingly shorter stroke. To avoid spreading the individual cylinders farther apart, a separate cylinder block with Nikasil-coated cylinders is used in lieu of the old bike's cast-in cylinders with separate liners. The intake valves are larger (30.5mm vs 29mm) and now titanium, and shorter exhaust valves allow the camshaft to be lower in the cylinder hed for a 15mm-lower overall profile. The camshafts themselves use a new casting process that allows their walls to be thinner, saving more than one pound overall. |
 An all-new frame is made up of four main castings compared with the old bike's nine pieces, for a 5.5-pound weight savings and a 30mm-narrower profile. Lateral rigidity is up 13 percent, torsional rigidity increases by 40 percent and vertical rigidity is up by 30 percent. |  The rear wheel is more than a half-pound lighter than the previous hoop, and the swingarm is 15mm longer. The engine appears to have been moved forward and up slightly, giving the swingarm more angle and allowing it to be longer without altering the wheelbase, which remains almost identical to the old model's. |  The 1000's underengine exhaust has a servo-operated valve as well as a pressure-operated valve to route gases through its three chambers appropriately. The swingarm is arched for clearance, and the dual-exit muffler is much smaller than it appears in pictures. |
 The slipper clutch-the first on a CBR model-uses a ramp-style two-piece hub. A second set of ramps pulls the two pieces together under acceleration, adding pressure and allowing the use of lighter clutch springs (the design is similar to that used on the Suzuki Hayabusa). In turn, a cable can be used instead of the old bike's hydraulic actuation. The swap from hydraulics to a cable somewhat offsets the additional weight of the slipper clutch. |  Nothing escaped Honda's weight-saving crusade on the 1000's front end: The wheel is a half-pound lighter, the rotors have fewer buttons (six compared with 10 each) and are drilled with four different sizes of holes, and the monobloc calipers have aluminum pistons instead of steel. The calipers (inset) are machined from the rear, plugged and welded, and their smaller size compared with conventional two-piece units allows the fork stance to be narrowed by 10mm, reducing aerodynamic drag and improving airflow to the radiator. Triple-clamp offset has been increased slightly to decrease trail by 4mm to 96mm. |  The Honda's stubby front end features two ram-air intakes that are routed through the new frame and into the airbox. The aerodynamic design, including the short front end and minimalist rear end, is based on MotoGP research showing that a smaller side profile results in reduced drag in transitions, quickening steering. The turn signals are incorporated into the mirror to further improve aerodynamics. |
 Other weight savings come from a smaller battery, a shorter radiator, an aluminum sidestand and a lighter HESD unit that is also moved slightly rearward (and closer to the bike's center of mass). The shorter radiator can also be mounted higher, as the ram-air tubes are now routed through the frame spars instead of between the bottom triple clamp and radiator. The shorter radiator, mounted higher, allows more room for the exhaust header to snake forward before going under the engine, in turn freeing up space for the underengine boom box. |
The dashed lines for rpm and countershaft speeds show the typical lag between the two as play in the gear dogs is taken up. The Ignition Interrupt Control System detects the difference as the engine increases speed while the countershaft doesn't, and issues a signal to reduce power momentarily. The solid lines indicate the typical speeds for each shaft with the system working.
Ignition Interrupt Control System
To improve the 1000's ride-ability, Honda concentrated on the all-important off/on throttle transition with a three-pronged solution to smoothing response. The addition of a slipper clutch reduces the tendency for chatter on deceleration, and the Idle Air Control Valve, first seen on last year's CBR600RR and incorporated into the '08 1000, reduces engine braking and eases the throttle's abruptness. The third aspect to improving the throttle transition is reducing driveline lash, which is addressed by Honda's Ignition Interrupt Control System. The transmission and its gear dogs are responsible for 50 percent of driveline play, and the system detects this lash by comparing crankshaft speed to countershaft speed. Any difference indicates the switch from deceleration to acceleration, and the ECU reduces power for up to 20 milliseconds-while the countershaft catches up to match the crankshaft's relative speed-to ease that transition. A different amount of interrupt is used for each gear, and the system is only active at 2500-6000 rpm; Honda reps indicate the setup is more for the street rider than for track use. It's an interesting and unique solution to a problem most manufacturers have addressed with electronically controlled butterfly valves in the throttle body, and the Honda CBRs are among the few sportbikes that retain a single, rider-controlled butterfly. The Ignition Interrupt Control System, using no new sensors or additional electronics and requiring only additional programming, potentially saves the weight and complexity of a secondary butterfly or more complicated ride-by-wire setup. It would seem an easy step from this system to extend the operating range and parameters to add rate-of-change traction control-again, no new sensors would be required-but a Honda representative pointed out that while implementing such a system would be relatively simple, the development time and costs to perfect it were prohibitive for this year's model.
No comments:
Post a Comment