by Kevin Duke

Less Weight, More Midrange on my CBR Please

In 1998, the 600cc sportbike class accounted for a significant 22,000 units sold in the U.S. Not bad, eh? Well, that ain’t nothin’, because sales in this ultra-competitive class have nearly tripled since then. Almost 55,000 middleweight sportbikes have been sold through October of this year, surpassing the mark set during the entire 12 months of 2003.

Obviously, success in the class is critical for all the players involved, something Honda knows as well as anyone. It’s been at or near the top of the sales charts during the 16 years since the CBR600’s 1987 introduction. It comes as no surprise, then, when a Honda PR wag tells the assembled media at the new CBR’s press launch that the class is considered “the core of the industry.”

Japanese manufacturers almost religiously stick to a four-year product cycle for sportbikes, providing updates to the core machine in its third year in production. It didn’t take a marketing whiz or engineering wizard to predict some of the mid-model updates to the supersport competitors from Honda and Yamaha.

Kawasaki got the jump on the middleweight field by being the first, in 2003, to adopt an inverted fork and radial-mount brakes to its ZX-6R. Suzuki followed suit in 2004 with both pricier components fitted to its new GSX-R600. That being the case, the two largest Japanese manufacturers were forced to “call” the hand played by the smaller factories.

You’ve probably already read our ride report on the 2005 Yamaha YZF-R6, and now we bring you the view from the Honda camp. Like the R6, the Honda CBR600RR receives a 41mm inverted fork, replacing the CBR’s 45mm conventional sliders previously employed. Despite the smaller-diameter stanchions, an upside-down fork is more resistant to flex than a slightly thicker conventional fork. Also like the Yamaha, Honda exchanged its 4-piston caliper front brakes for higher-spec radial-mount units, Tokicos in the Honda’s case.

Yamaha made alterations to the R6’s intake system, and-you guessed it-so did Honda. But instead of a slight increase in throttle body size and some experiments with venturi lengths, Honda went inside the cylinder head and reshaped its intake ports. Their smaller sizes increase intake velocities that result in stronger midrange power, addressing one of our biggest complaints about the 2003-04 models.

The other obvious flaw of the CBR only really makes itself known when rolling it onto our electronic scales. Last year’s CBR scaled in a whopping 26 pounds more than any of its class rivals. At 420 pounds with its fuel tank empty, it was even lardier than three Japanese literbikes, so Honda put the CBR on a diet.

At first glance, the 2005 CBR visually distinguishes itself from the previous model by the aforementioned brakes and fork, but the revisions go much deeper than that. The aluminum frame appears unchanged, but it is in fact a totally new component that scales in 3.6 pounds lighter. The CBR’s Large Project Leader Hitoshi Akaoka told me the walls of the casting were made thinner where it didn’t affect frame stiffness, resulting in a frame that is lighter but just as rigid.

When asked which aspect of the new CBR he’s most proud of, Akaoka said it’s the 9-pound weight reduction, and it’s easy to see why when you look at the list of components redesigned to save a gram here and an ounce there. The aluminum subframe is 17.5 ounces lighter, while the center-up exhaust system has lost 20.1 ounces despite now carrying catalytic converters. A new swingarm shaves 4.4 ounces. Also lighter for ’05 is the simplified rear cowl/seat section, the rear shock, axles, sidestand bracket, sprocket, peg brackets and chain adjuster. Even the upper triple clamp was redesigned to reduce mass, as its new gullwing shape allows a slight reduction in the length of the fork tubes.

Much of the CBR’s bodywork has been changed, although it takes a keen eye to notice. A mix of elements from the CBR1000RR and MotoGP’s RC211V meld with the little RR’s familiar face, giving it a sharper-edged look. A “Racing” decal on the side fairings and a new seat release keyhole between the pilot and passenger seats further distinguish the ’05 CBR from its predecessors.

If the proof is in the pudding, then Buttonwillow Raceway is a giant dessert spoon. Honda recently invited the media to sample the freshened CBR at the isolated track west of Bakersfield, California. Honda must’ve felt bad about putting jaded motojournalists up at the Super 8 next to the busy I-5 highway, so they made sure that we were well taken care of at the track. Each journalist had his own CBR to ride on this cool morning, and a crew from Dunlop Japan was there with tire warmers and fresh rubber.

With my black and silver CBR sitting up on jackstands, I simply had to walk up to the bike and American Honda’s hard-working Bob Oman was there to strip the tire warmers and lower the bike down for my tender thrashing - just like being a factory rider for the day. But you probably don’t care to read about how Buttonwillow isn’t the most glamorous of racetracks or how a spoiled journalist gets pampered, especially if you’re digging yourself out of the snow somewhere in the Midwest and won’t be riding for several months.

After scrubbing in the Dunlop D218s on the cool pavement for a few laps, it was time to pick up the pace. Getting on the gas hard, it became immediately apparent that the new CBR has much better midrange throttle response. Whereas the old bike was weak in the mid-rpm range with a flat spot from 9,000-10,500 rpm, the new bike seems to pull in a more linear fashion that still retains its strong top-end hit.

Honda’s RR edition of its CBR600 has always impressed us with its unshakable stability and smooth-shifting gearbox, and this new iteration is no different. But that stability comes at a price. The esses section of the 1.86-mile West Loop demands a flickable motorcycle, but the CBR required a lot of steering effort during the quick transitions. When I mentioned to Akaoka-san about the CBR’s reluctance to turn as quick as some of the other 600s, he said that he didn’t want to sacrifice stability. His team could’ve made the new bike’s steering geometry more radical than its 24.0-degree rake and 95mm of trail, but a steeper rake and less trail results in a nervous feel from the front end that can sap rider confidence, and the engineer didn’t want to use the Band-Aid solution of a steering damper. At the end of the conversation, Akaoka admitted he might have to go with quicker steering geometry in the future.

The standard Dunlop D218 street-compound tires (now lighter than ever) were sticking quite well, although a two-wheel drift at the apex of one corner did catch me off-guard. Ever since motorcycles have adopted widespread use of fuel injection, a common complaint is the sudden response when re-applying throttle. The CBR is average in this respect. Some injection systems just transition more smoothly than others.

The same goes for an engine’s reaction when coming off throttle. As emissions regulations get more stringent, a greater emphasis is placed on cleaning up the exhaust gases during compression braking, so fuel flow with the throttle closed is shut off instead of engine vacuum pulling a slight flow through a carburetor. On the CBR, this sensation is noticeable, and it’s what caused my “moment” at the north end of the circuit.

Having been re-familiarized with Buttonwillow’s twists and turns, I finally began testing the new brakes. They feel similar to the radial-mount units on the ’05 R6 - very controllable with lots of power. Later on, I went out to compare the ’04 CBR Honda had at the track. Its brakes were impressively powerful, but there is more feedback available from the radial-mount brakes on the new bike; it is more direct and, hence, more controllable.

One of the trickier sections of Buttonwillow is a gradual right-hander that leads into a high-speed sweeper. It would be nothing complicated if not for a decent-sized bump at the point where you’re trying to twist hard on the throttle. I was impressed with the ’05 CBR’s ability to plow through nearly unperturbed, becoming one less thing to worry about around the track.

It wasn’t until I rode the 2004 bike that I fully realized the improvement Honda has made by utilizing the new 41mm inverted fork instead of the 45mm “right-side-up” fork. Going through the aforementioned corner and running through the same line, the ’04 chassis gave a wiggle that was likely due to the less rigid fork. It’s nothing that a casual street rider would ever notice, but it’s something that you could do without on the racetrack. If you do spend time at the track, it’s good to know that Honda offers contingency payouts in most U.S. race organizations.

One battle CBR racers will still have to deal with-despite the weight loss-is a bike heavier than any other top-line 600. Some journos claimed they could feel the effects of the 9-pound reduction but I was more skeptical. The new bike was just as much of a chore to run through the essess or bend into the high-speed dogleg kink leading up to the hill. Our ’04 test bike weighed in at 420 pounds with its fuel tank empty, so the new bike should weigh 411 pounds if Honda’s claims are to be believed. While the reduction of mass is admirable, the CBR will still scale in 17 pounds heavier than the Suzuki GSX-R600, the next-heaviest 600, and 26 pounds more than the class lightweight Kawasaki ZX-6R.

Once again, we have to blame Honda’s burly Unit Pro-Link swingarm (that contains the shock at both ends instead of one end mounting to the frame) and the underseat exhaust for the extra pork of the CBR-RR. It will be interesting to see how the new ZX-6’s undertail exhaust system affects its weight.

While we ate lunch inside, our crew members were busy fitting Dunlop’s evolution of its D208GP tires. While the front tire remains similar to the earlier generation, the rear is lighter and has a softer compound for better performance and more grip. Dunlop’s PR guy (and former motojournalist) Ken Vreeke noted that “it’s a much friendlier tire” for fine-tuning a race setup.

We can’t verify that claim from our time on the CBRs, as Honda’s chief testing guy (and former World Endurance champ) Doug Toland consistently nails the best setup for each track prior to any journo turning a wheel. To better cope with the additional cornering loads made possible by the sticky tires, Toland dialed in extra preload, while a reduction in compression damping kept the settings from being too harsh. The pressure in the rear 208 was reduced to 29 psi from the 34 psi in the 218s; the fronts were kept at 31 psi.

Toland’s new setup felt much stiffer, especially at the rear. The extra traction of the race-compound tires not only produced higher corner speeds, as you’d expect, it also allowed for more confidence when getting on the throttle during corner exits. Dunlop is the dominant force in motorcycle tires in this country, so we’ve been testing several of the smaller players in this market over the past few years. We’ve had good success with offerings from Pirelli, Michelin and even Bridgestone, and this new Dunlop ranks up there with any you’d care to mention.

Once again, we noted the CBR’s terrific stability when hard on the excellent brakes, as on the previous versions, and headshake was non-existent when the new bike’s added midrange power was called upon to squirt the CBR up to speed on the straights.

We came away from our day aboard the ’05 CBR600RR pleased. Not only did we get first-class treatment during a day at the track, we also got to see Honda address some of the complaints we’ve levied at the old bike: chiefly, its weight and midrange power. Plus, it threw in incremental increases in braking and chassis performance as a bonus.

But all these tweaks cost money, forcing Honda to add $200 to the CBR’s already pricy MSRP ($400, to $8,999, as of February –Ed). If you could get a set of bitchin’ radial-mount brakes and an inverted fork fitted to your 2004 CBR for a measly $200, it would be quite a bargain. However, the 2005 CBR’s $8,799 price is higher than the other 600s, and more than even the new Triumph 650. With the CBR’s extra weight and relatively high cost, Honda must be pricing its bike by the pound.

Still, there’s no denying that the new CBR is a step forward from the previous version. The competition, however, hasn’t stood still. The improved R6 ($8,399) and totally revised ZX-6R ($8,599) will likely give the Honda a run for its money.