The '05 Honda CBR600RR: dramatic improvements to what was already a good sportbike.

I've been a motojournalist for eight years, and I've been to a bunch of new model intros for all kinds of bikes. However, I've never attended a more subdued tech briefing on a motorcycle than the one held at Buttonwillow Raceway for the 2005 Honda CBR600RR. Usually, the development team and the PR folks go over every detail of what makes the bike they're selling to us better than last year's-or in the case of an all-new model-better than any other bike ever manufactured. This minutia is interesting, fun even. After all, if I didn't care about this stuff, I wouldn't have chosen a career in the motorcycle industry. Still, I've attended longer pre-ride presentations for bikes whose annual change consisted of basically bold new graphics. It's part of the game. The manufacturers know they've got a captive audience that is eager for information to pass on to readers-and there's the little thing of the often exotic locale, delectable food, swag, and the ride to help make the junket a positive experience that hopefully rubs off on the product at hand. After all, we're human, and if we're already in a great mood when we go to ride the new motorcycle, we might be inclined to let that positive energy wrap itself around the bike, too.

Note the tail section. Does the subframe look 17.5 ounces lighter to you?

As journalists, we're cognizant of this dance with the PR folks. Travel and good food are always fun. Besides, we hunger for the information that only factory insiders can give us. You'd be surprised what you can learn over a burrito lunch with a test rider or an after ride beer (or two) with an engineer. Still, the heart of a sportbike introduction is the tech briefing where the defining characteristics of a bike are outlined and explained. Often, the briefing will help us develop our list of things to ponder while out actually riding the bike. So, leaving a briefing that was surprisingly short with more than an hour of down time before I would don my leathers and actually throw a leg over the bike calls attention to itself. What was Honda up to? Why no song and dance?

Radial mount calipers and 310mm discs mean precise speed control.

Apparently Honda has been concentrating on four things while creating the 2005 CBR600RR: reducing the weight of the bike, upgrading certain components, increasing mid-range power, and re-sculpting the bike's appearance.

If you've paid any attention at all to the CBR600RR, you know that, despite its strengths, it suffered from an excess of heft (as do many of us). Despite all evidence to the contrary that is exhibited at fast food restaurants nationwide, reducing the weight in humans is significantly easier than it is in a current generation sportbike. Honda's task with the 600RR was remove material from areas that it wasn't needed and keep it where it was for a total reduction in weight of nine pounds when compared to the 04 model. Because of Honda's mass centralization philosophy, the bulk of the, uh, bulk was removed from the ends of the bike. (For those who need a little refresher on mass centralization, just think about a seesaw. The closer you place the weight to the pivot point, the easier it is to rock the teeter-totter up and down.) So, looking at the rear of the bike, the sub-frame lost 17.5 ounces. Be removing unnecessary fasteners from the under-seat exhaust, engineers lopped off 20.1 ounces from the assembly while adding a catalytic converter to the system. Using an extruded exhaust pipe (instead of last year's welded piece) to feed the muffler assists in reducing the weight of the system. A new top shock mount that is cast into the swingarm saves 4.4 ounces over last year's bolt-on assembly. The shock itself is shorter and lighter with the change of the preload adjuster ring from steel to aluminum illustrating how much detail was focused on losing weight.

Even the super slim instrument cluster contributed to the CBR600RR lightening project.

On the front of the 600RR, the weight reduction was complicated by the addition of 41mm inverted Honda Multi-Action System (HMAS) cartridge fork. While inverted forks do lessen the unsprung weight of the front wheel, the overall assembly is heavier than a traditional fork. To minimize the effect of the new fork on the bike's slim down program, a gull-wing-type top triple clamp allowed for shorter fork tubes to be utilized and save a little weight. A shorter front axle also trims both unsprung and overall weight.

The new, improved, and lighter cast top shock mount.

The largest, single change in weight came from the frame itself. By using improved casting processes, the wall sections are thinner-with the amount varying depending on the location-to shave 3.6 pounds off the total while not compromising the frame's performance. At the other end of the spectrum, numerous smaller items were lightened. Even seemingly inconsequential items like adding the CBR1000RR-type rear master cylinder and push chain adjusters (which happen to be both lighter and stronger) or triming handlebar bosses and footpeg brackets contributed to the weight savings. The end result of all this noodling was a power-to-weight ratio that improved from 3.76:1 to 3.58:1, which translates into 3.58 pounds for every horsepower produced.

Now that inverted forks have swept the major players of the 600 class, what technology do we ask for next?

Honda's second goal for the 2005 CBR600RR was to upgrade various components to keep up with the march of technology. Topping that list is the already noted, fully adjustable 41mm inverted fork. The second most important change-and one that street riders will appreciate on every ride-is the inclusion of radial mount calipers. Remember when only GP bikes sported these babies? Now, we can all appreciate them as they've moved wholesale into sportbiking's most popular class. The design delivers more powerful brakes by resisting deflection under the stresses of turning velocity into heat. Honda claims that its caliper design allows for a central bolt (in addition to the two outboard bolts) which helps hold the caliper together more rigidly, resulting in consistent pressure distribution and, more importantly, better feel at the lever. The discs on the receiving end of the brake pads are the same 310mm as last year.

Hitoshi Akaoka was the Large Group Leader on the CBR600RR upgrades. If you see him, say, "Thank you."

The 600RR wears new rubber for 05. The OE specific Dunlop D218 tires actually fit into both of Honda's design goals for the bike. First, they are lighter than the D208 tires on the 04 model. Lighter tires make a big difference for a couple of reasons. The weight has to be accelerated twice: as part of the bike's overall weight and part of the rotational mass of the wheels. So, all things staying equal, lighter tires would help a bike accelerate, stop and turn more quickly. Throw in the D218's formidable grip and wear characteristics, and this update to the 600RR sounds pretty good.

What updated sportbike doesn't feature a claimed improvement of power delivery? Well, the CBR600RR is no different. However, instead of working on peak horsepower, Honda chose to focus on improving the mid-range power. Although the Dual Stage Fuel Injection concept remains the same with port injectors inside the throttle body and shower head injectors (which only operate above 5500 rpm) mounted to the top of the airbox, some functional changes were made. The injectors still have 12 holes, but they have been redesigned to flow fuel more quickly. The intake ports were reshaped to include a venturi section that accelerates the fuel charge to more efficiently fill the cylinders. When combined with the better flowing exhaust system and updated EFI and ignition maps, the engine makes more power from 4000-7000 rpm. While racers are loathe to let their rpms drop to this level, the reality of street riding makes this a desirable change. Honda claims this bump in the middle did not come at the expense of the top end. Only dyno charts will tell that story.

The final category of changes Honda planned for the CBR600RR is appearance. When you've got what is arguably the best GP bike in the world, why not try to make your street sporting machinery more closely resemble it, right? Also, while the bodywork is being redesigned, it can be made lighter to meet design goal number one. So, the front is more angular with a revised ram air intake and headlights. The rear section has been made of two pieces instead of one and saves some weight. The revision in its shape is subtle but noticeable. Having an 04 model to directly compare the new bodywork to is really the only way to spot all of the changes.

So, the real question is: Do all of these changes make for a dramatically different bike or a merely updated CBR600RR? Honda was kind enough to supply a pair of 04 Rrs to help us experience the difference in the 05. Sitting on the bike at a stand-still gives no immediate feedback. The two years are essentially the same. However, once under way, the 05 model is immediately more nimble. At speed, the 05 changes direction much easier. Where the 04 model seems to like more decisive inputs, the 05 responds well to a light touch. For example, when entering a decreasing radius corner, I was able to easily dial in several small steering inputs to follow my chosen line while the 04 was a little more resistant. This could very well be due to a slight difference between the D218 and D208 in the tire profile, but the Dunlop representative present at the introduction said that the profiles are essentially unchanged. So, I would surmise that the lighter front tire is at least partially responsible for the easier turn in. When changing directions from side-to-side through Buttonwillow's S-bends, the new RR felt more sprightly, clearly an example of the lessened weight reduction.

Determining the individual effect of the weight reduction on acceleration is more difficult. Rather, you have to consider the combined effect of the lessened weight and increased power. I have always been more of a mid-range rider than a top-end ripper, and I can say that exiting corners, the 600RR's power is noticeably improved, pulling more willingly out of the mid-range into the power band. When ridden back-to-back, the difference between the models is clear. Although I couldn't detect a difference in top-end power, the 05 starts pulling much earlier. Street riders will appreciate this when riding on unfamiliar roads.

Specifications: 2005 Honda CBR600RR

MSRP: $8799 Engine Type: 599cc liquid-cooled inline four-cylinder Bore and Stroke: 67 x 42.5mm Compression Ratio: 12.0:1 Valve Train: DOHC; four valves per cylinder Carburetion: Dual Stage Fuel Injection, 40 mm throttle bodies Ignition: Computer-controlled digital transistorized with three-dimensional mapping Transmission: Close-ratio six-speed Final Drive: #525 O-ring-sealed chain Suspension Front: 41mm inverted HMAS Cartridge fork with adjustments for preload, compression and rebound damping; 4.7 inches travel Rear: Unit Pro-Link HMAS single shock with spring preload, rebound and compression damping adjustability; 5.1 inches travel Brakes Front: Dual 310mm floating discs with radial mount four-piston calipers Rear: Single 220mm disc with single-piston caliper Tires Front: Dunlop D218; 120/70-ZR17 Rear: Dunlop D218; 180/55-ZR17 Wheelbase: 54.5 in. Rake (Caster Angle): 24.0 degrees Trail: 95mm (3.7 in.) Seat Height: 32.3 in. Dry Weight: 361 lbs. Fuel Capacity: 4.8 gal. Colors: Red/Black, Metallic Silver/Black, Black/Tribal, Black

The carburetion feels much cleaner in the 05. Off-throttle to on-throttle transitions experienced mid-corner are smooth, allowing you to direct attention elsewhere. Occasionally, in one decreasing radius corner, I did encounter a lurch when going from neutral throttle to deceleration. While this never upset the chassis, it surprised me the first few times since the EFI was otherwise so seamless. Although direct comparisons to the competition will have to wait, my gut feeling about how the CBR600RR compares to the R6 I rode only a few weeks ago is that the CBR's injection is better sorted out with almost no abruptness. Even though the power output is much better, I think it may still be a tick or two behind the R6.

The brakes on the CBR600RR are nothing short of phenomenal. They offer an excellent combination of power and feel. I was able to get the same power out of the 04's brakes but with much higher effort and less feel. As the day progressed, I found myself charging further in towards the corners before hauling the bike down from speed. Radial mount calipers are a boon to both street and track riders. The extra power will keep closed course junkies grinning while the extra finesse available to your right fingers will pay dividends when trail braking into an unfamiliar corner.

Buttonwillow has some bumpy sections to the track, and the CBR's suspension kept the chassis stable through the worst of the undulations. The stout front end contributed to my braking confidence. On one lap, I let the rear tire touch the curbing at the exit of the corner, and the back end stepped out with enough force to knock my foot from the outside peg. The Unit Pro-Link rear suspension made it possible for the bike to gather itself up without any problems. I've faced similar situations on other bikes with a bit more drama involved. Dunlop's D218 tires performed well during the half day of track riding that they were on the bike. I never felt limited by the tires as my speeds ramped up. When the rear broke free under power, it did so benignly. I'm sure I could have gotten a couple more track sessions out of the tires before they showed any ill-effects.

After a day at the track riding both the 04 and 05 CBR600RRs, I'd have to say that Honda has made some pretty dramatic improvements to what was already a good sportbike. Was Honda's decision to keep the briefing short an approach taken by people confident enough in their product to let it speak for itself? I think so.

The 05 600RR will be a formidable force in the middleweight sportbikes. Now, if we could only get all the OEs to race their 600s in the same class ...