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Motorcycle News, Editorials, Product Reviews and Bike Reviews

2003 Honda CBR600RR: MD Track Report Part Two

Part One provided highlights of some of the technical aspects of the 600RR and its performance on the Las Vegas Motor Speedway (LVMS). This second installment will go much further in depth . . . hopefully, to tell you all you want to know about the new supersport screamer from Honda. And a screamer it is.

The new bike is a model that Honda is obviously very proud of, and one that has close appearance and engineering ties to the all-conquering RC211V that Valentino Rossi used to squash the competition in the 2002 MotoGP season. It represents a new (for Honda) approach to the middleweight class, one that sees the F4i remain in the 2003 line-up alongside the 600RR. Honda is pinning its national and world supersport domination hopes on the 600RR, while the less focused, but still very capable F4i possibly remains a better choice for day-to-day street riding. We’ll know this last part soon, as we anticipate taking delivery of a 600RR street test unit.

Honda RC211V

2003 CBR600RR

A phrase I heard more than once at the Honda tech briefing was “real-time development”, and it was being used to describe the development process of the 600RR in relation to the development of the RC211V. Not six months after the start of the RC211V project, the 600RR project began. Technology and design in GP bikes usually take years to find their way into a street bike, if ever. This time it has happened in the same year, hence the phrase “real-time development”. This almost parallel development program in effect makes this 600 a race bike that made it to the street.

Mass centralization is paramount to Honda, and in the RC211V, this concept has been taken to a new level. Efforts to move fuel, engine and rider as close as possible to the motorcycle’s roll axis demanded new designs. The engineers realized that some of the technology and design from the RC could be transferred directly to the 600RR with the same benefits as those realized on Rossi’s race bike. This transfer started at the gas tank.

Getting fuel to the center of the bike is a big deal, since each gallon of fuel is quite heavy (at just shy of six pounds). The 600RR’s gas tank design and placement were crucial to getting the fuel load low and centered. From frame rail level, fully two-thirds of the 4.8 gallon gas tank remains below, nearly touching the top of the engine’s crankcases. Looking from the side at the main frame spars, the fuel tank silhouette stops just behind the frame weld.

It could be said that the fuel tank placement drove the need for a new rear suspension design, or that the Unit Pro-Link gave the engineers an opportunity to optimize the fuel storage arrangement. It’s kind of a “chicken or the egg” conundrum. Whichever way you look at it, the new Unit Pro-Link rear suspension helped to make room for the lower placement of the gas tank. The new design sees the top shock mount bolted to the top of the swingarm, instead of the rear of the frame. Since there is no top shock mount incorporated in the frame like you find on other current motorcycles, this space is opened up for fuel storage.

The rider, on average, makes up one third of the total rider and bike weight combination (a little more than that, in my case – ahem) making rider placement another important element in mass centralization. The 600RR places the rider 70mm further forward than on the F4i. The new gas tank makes this possible.

The all-new 599cc engine’s role in this concept is to get small, smaller than the F4i’s mill. To this end, it has become shorter, at 236mm vs. the F4i’s 266mm front to back and 21.5mm narrower in width, after a rearrangement of various parts contained within the crankcases.

The result is a motorcycle that packs its heaviest components so densely at its center, that you literally cannot see through to the other side with the bodywork removed. Parts that could not be repositioned were lightened. Wheel hubs, light assemblies, instrument clusters, etc., did not escape scrutiny and all were suitably trimmed of as much weight as possible to keep weight furthest from the CG to a minimum.

Now, back to the engine. As stated before, it is all-new. Bore and stroke dimensions of 67mm x 42.5mm are the same as the F4i’s, although Honda did experiment with other bore/stroke dimensions. Compression ratio also remains unchanged. Redline has risen to 15,000 rpm, and, to reliably attain these engine speeds, parts needed to be made lighter. A savings of 34 grams per cylinder was realized with lighter piston pins, forged pistons and carburised, nutless connecting rods (like those originally found in the 1998 Superhawk).

Up top, exhaust valves remain the same size, but the intake valves have grown 1mm in diameter to 27.5 mm. Keeping them from an unwanted meeting with the piston are nested pairs of valve springs. Each spring exerts lighter pressure, but when paired, overall spring pressure is higher. Contact between the springs damps out the surge that can allow the bucket tappet to lose contact with the cam lobe. A new cam chain tensioner design has dual pivots, placing one near the cam sprocket to prevent cam chain whip and to better maintain cam timing at high rpms.

To help make the engine more compact, the mainshaft was moved 48.4mm above the crankcases’ centerline. This allows the countershaft to be moved closer to the crankshaft, creating a triangulated layout. Although this shaft layout is new to this motor, some other sportbike engines utilize a similar design.

The exhaust ports are rotated 30 degrees downward, allowing the exhaust headers to more closely follow the front of the engine without needing a power-robbing, sharp bend coming out of the exhaust port. This in turn allows the engine to be moved 9mm forward to place more weight on the front wheel.

Cornering clearance has been improved by moving the crankshaft mounted starter gear from Honda’s typical left-end location to the right hand side. This made it possible to move the left-end mounted AC generator inboard by 21.5mm. This relocation of parts, combined with reshaping the engine covers, has increased possible bank angle by 3 degrees. For all you crankcase draggers, this is good news.

The engine makes more power, and with more power comes more heat. Keeping the engine cool is a larger capacity radiator, and a new, one-piece fan assembly.

This is all neat stuff, I know, but you probably want to know how much power it makes. Honda claims 117 h.p. @ 12,500 rpm, and peak torque comes in at 49.9 ft.lbs. @ 10,000 rpm. These are figures taken at the crankshaft, and your local rear-wheel dyno is not likely to mirror these numbers.

Tending to the engine’s appetite for fuel and air is a new dual-stage ram air and dual-stage fuel injection system. Air enters the ram air system via larger diameter air ducts. Wind tunnel testing is said by Honda to have shown an increase of steering effort due to the larger ducts, so the engineers broke out the drill and put a bunch of holes in the ducts. Problem solved. Ummm, okay.

In the new fuel injection setup, a primary set of 12-hole injectors is mounted in 40mm throttle bodies (compared to the F4i’s 38mm units) located in the traditional location. A second set of 12-hole fuel injectors are positioned above each velocity stack in the larger, 15-liter air box. The distance of the second bank of injectors from the intake valve gives fuel extra time to properly vaporize. The extra distance also cools the fuel air mix, giving a slightly denser charge. Although the second set of injectors are said to kick in at 5500 rpm, after speaking with the engineer responsible for the F.I. system, he said that throttle position also needs to be open greater than 40%, regardless of rpm, for the second set of injectors to activate. When they are active, the upper set of injectors delivers their fuel just a fraction of a second before the primary injectors do. A 32-bit processor makes sure there is enough computing power to handle the eight injectors and higher redline.

Some chassis improvements are the product of Honda’s new “Hollow Fine Die-Cast technique”, which allows thinner walls (2.5mm vs. 3.5mm) without sacrificing strength. A ceramic-coated, sand-formed interior mold – a sunanakago, the Japanese call it – makes it possible. The steering head, downtube structures, and the swingarm plates are formed using this new casting technique. This casting technique also makes it possible to dial in specific rigidities according to handling needs.

The rear sub-frame is made the same way and is quite intricate, but light, with strengthening ribs to support the new center-up exhaust. Compared to the F4i, the 600RR’s chassis has greater torsional (twisting) stiffness at the steering head, and decreased lateral stiffness through the thinner frame rails.

While Honda has moved the top shock mount from its traditional location in the frame, the lower part of the shock still bolts to linkage, which is in turn attached to the lower part of the frame via a pair of dog bones. Honda calls it Unit Pro-Link. When the rear suspension encounters a bump, the road shock ideally is absorbed solely through spring and hydraulic resistance. But part of this road shock reaches the chassis. The portion of the road shock that isn’t absorbed follows a load path that goes up the length of the shock. In a traditional rear suspension, that means the energy not absorbed by the shock is fed into the frame, affecting the motorcycle’s stability and ride quality.

With the new Unit Pro-Link, the left-over energy still follows the same path up the shock, but since the top shock mount is now attached to the swingarm, the left over energy is dissipated through the linkage and swingarm instead of the frame, leaving the rest of the motorcycle largely undisturbed while it tracks over the bumps. According to Honda, the benefits of this design are faster, smoother corner entry, and earlier throttle application exiting a corner (with comparatively less wheel spin).

The swingarm itself is a massively braced design, with a press-forged right side, a box-section extrusion left side, and both sides welded to a cast cross member. It is 43mm longer than the F4i’s unit, and the longest in the class, taking advantage of the 30mm of room made available by the shorter engine. A longer swingarm shifts weight bias forward and makes for a more progressive suspension action by reducing the angle the swingarm rotates for a given suspension movement.

Compared to the F4i, the 600RR’s rear shock has a piggyback reservoir, instead of a remote reservoir and greater damper volume. It is self-contained in the swingarm and its position in the Unit Pro-Link swingarm is lower than you would find with a traditional shock mount design.

Up front, Honda has stayed the course with conventional design “right side up” cartridge forks, although they have grown in diameter from the F4i’s 43mm tubes to 45mm. I asked if Honda had tested with upside down forks, and they admitted they had, but because they didn’t give the “feel” they sought, they went with the conventional fork design.

Likewise, with the brakes, radial mount calipers were tried, but because Honda engineers felt there was no discernable difference, the 600RR ends up with conventionally mounted brake calipers gripping larger, 310mm rotors, vs. the F4i’s 296mm discs. These rotors also have one more rotor carrier mounting button, compared to the F4i. The rear brake is the same 220mm rotor gripped by a two-piston caliper.

Claimed dry weight of the 600RR is the same as the F4i’s, at 370 lbs. While some parts on the 600RR got lighter, others got heavier, like the larger diameter fork tubes, front rotors, and the swingarm, although its weight is still pretty well centered on the bike. Add a second set of fuel injectors, and you have a bike that weighs the same, but carries that weight better.

I’m a rookie at press introductions, still, but I was very impressed with the execution of this event. We met for breakfast at Freddie’s and got our description of the track, the proper line around the track and passing instructions. Each rider was assigned a 600RR to ride for the day, and a Honda technician was present to support each pair of rider’s requests for changes and adjustments to their mounts. Engineers who were on the 600RR project also were in attendance to answer the questions rattling around in our heads.

To help minimize time spent searching for a good motorcycle setup, Freddie Spencer, and his instructors Nick Ienatsch, and Jeff Haney (along with Honda test rider Doug Toland) all worked on setting up the suspension, and control positions of each bike prior to our arrival. Jim Allen from Dunlop USA, and tire engineers from Dunlop Japan, looked after tire pressures and tire wear. This collection of hugely talented individuals ensured that we did not waste time in the garage as we searched for the right settings. As I stated in part one, this setup worked well, and was probably perfect for me after I added a little more compression damping to the forks.

Although the temperature in the morning was initially a little on the cool side, the tires were nice and toasty, thanks to the tire warmers wrapped around the OE Dunlop 208ZRs. My technician, Byron Johnson, had me sit on the bike while it was on it stands to make sure the shift and brake levers were placed properly for my feet and hands. After raising the shift lever slightly, I was all set for the first session.

Rolling out of the garage for the first morning session, I couldn’t help but notice how I was only able to tip-toe the ground as I rolled out of the garage. Comparing specifications between the RR and the F4i shows that the RR’s seat height is 32.3 inches, while the F4i’s height is 31.7 inches, plus, the suspension of the RR was racetrack stiff. Then again, I have short legs . . . For reference, I have a 30-inch inseam.

Jeff Haney and Nick Ienatsch split us into two groups of four to lead us around for a few laps. They wanted to make sure we understood what the fast line is. They later circulated amongst the group to provide additional instruction where needed. This was a new track for me, so these instructional laps were invaluable, and allowed me to quickly get up to a speed where I could gain meaningful feedback from the bike. During these slow laps, I had time to notice throttle response and low speed handling, all of which felt extremely refined, doing exactly what you wanted. As I picked up speed, the suspension that felt too stiff started feeling better, but I thought I’d try something softer.

For the second session, I requested softer suspension settings, because I like the bike to move around a little. The bike told me about half way into the first lap that this wasn’t the way to go. It moved around more, alright, as steering precision suffered, and the bike took a bit longer to settle after the transitions between the banking and infield. Transitions from hard left to right and back felt rather sloppy, too. Cornering clearance had predictably decreased, but still only the peg feelers dragged, albeit more persistently.

Even though this clearly was not the hot setup, the RR did nothing threatening. It just humored me as I indulged my need to experiment. A quick trip to the garage to have the suspension returned to its original settings took only a minute, which had Byron and a curious engineer smiling knowingly…. Back on the track, all was well again and I vowed not to stray from the settings that the Great Ones had arrived at.

As I got more comfortable with the track and got faster, the bike took really good care of me. When I would miss an apex, a brake marker, or exit a corner a gear higher than I should have, it took it all in stride and made it look like that was the right thing to do for that corner. It is a very forgiving motorcycle to ride, at any speed.

Exiting the infield out onto the LVMS banking, the fast line carries you over a painted stripe two times. Leaned over far enough to touch a peg and a knee with the throttle pinned at about 125mph, the rear of the bike would step out slightly as the tire crossed the stripe, but the bike never gave more than a little twitch. The deeper the angle of attack across this stripe, the less of a twitch you’d feel.

Driving out of turn three, I got a little greedy with the throttle and the rear stepped out a fair bit. This situation has the potential of over loading the front end, causing it to push, or worse, completely wash out. Neither happened. As a matter of fact, the front of the bike behaved as though nothing was amiss out back. This is as much due to the bike’s handling characteristics as it is the Dunlops, with their always-friendly warning zone at the edge of sanity.

As I rolled out onto the track for the third session, I felt confident about which way the track went (always a good thing) and picked up the pace. It was the last session before lunch and the sun had warmed the track to go along with the hot Dunlops. Higher speeds brought deeper lean angles, but unless you were carrying a bunch of corner speed or – ahem – not hanging off far enough (the real reason, thanks Mr. Haney!), nothing touched down. I only touched footpeg feelers occasionally during this last session.

All of the morning sessions were on the stock Dunlop 208 ZR tires. They held up very well to the track speeds, with consistent feel from vertical to peg-feeler-touching lean angles. The front stayed hooked up for all of my morning sessions (as I held back a bit on the real aggressive braking), but the rear was starting to feel the pressure, and an occasional slide here and there served warning that it wasn’t meant for this level of abuse. It could be that the rear tire pressure in the OE rubber was much higher than you’d expect for track duty (see setup chart pic). Byron wrote down comments from my feedback, and would have made any adjustments I requested, but I didn’t ask for any, since I was still getting up to speed and wanted to become familiar with the bike’s current setup so that I would know if my changes were for the better or worse.

After I got back to the garage, I jotted down a few notes, and got some coaching from Jeff Haney. He adjusted my body position to get off the bike more, further to the inside. After a little practice on a stationary bike, I got the idea and stored it away for the afternoon sessions. During the break, I did laps in my head while the Honda mechanics and Dunlop personnel were hard at work swapping wheels with OE rubber for wheels wearing a Dunlop 208GP up front, and a 208GP-A rear. A distinct lack of tread toward the edge of the rear tire identifies it as a dry-weather track tire specifically built for the rigors of supersport racing. I did not see myself asking too much of these tires.

For the first afternoon session, I followed Jeff around for a few laps while the hot, but unscrubbed tires gradually made their acquaintance with the LVMS tarmac. At the lower speeds, I could concentrate on my body position, instead of worrying about brake markers and turn in points. A few laps went by with Jeff watching me in the mirrors to make sure I wasn’t slacking, and then I got the thumbs up from Jeff to go by.

Higher speeds at the racetrack sometimes reveal flaws, small and large, but in the case of the 600RR, it just wanted more. My track knowledge had become sufficient in that I didn’t need to think too much about what I needed to do for the next corner so I could concentrate more on what the bike was doing.

Although the front suspension preload was set at maximum, I was able to bottom the forks in the heavy braking zone approaching the hairpin corner coming off the back straight. Even though I had the front wheel hopping on a bottomed fork a couple of times (adding a half turn of compression damping helped this) the bike never got out of shape, and never even wiggled in the slightest or lifted the rear wheel. Braking earlier, but not as heavy, for this corner meant the forks could still absorb bumps and allow the RR to turn in when I needed it to. Easing off the brake as I neared the apex, the bike’s steering manners never threw any curve balls for me to catch. It simply went where I pointed it.

Braking was not as strong as I’d wished for, with initial bite and overall power a little lacking for my tastes. They were consistent, however, and never faded, always giving good feel and feedback. My experience with brakes tells me that I can get the power and initial bite I want with a simple swap of brake pads. I was told by the engineers that they could have gone further with braking power, but had to keep in mind the street use the bike will inevitably see. Touchy brakes on the street can mean bad things….. I have warped rotors in a single track day before, and while I put on more miles (over 230) this day at the track than I have at others in the past, the braking remained smooth on my final approach to the pits, with no tell-tale pulse from the front lever.

Engine performance at a racetrack can be misleading, unless you have a basis for comparison, (like some street miles), or another 600. Although there were F4i’s available for comparison, I was unable to stage any acceleration contests with riders who took out an F4i. It seemed they were always riding them a bit more tentatively than they did the RRs….

Nonetheless, while driving out of any corner at around 9000 rpm or higher, you get strong linear drive that has the bike headed for the next curve in a hurry. The bike rushes smoothly to redline, with no discernable steps in the powerband. It feels revvier than the F4i’s engine in my girlfriend’s 2001 model, and a bit stronger, based on our experiences, but only back-to-back comparison with its F4i stablemate will bear that out. Accelerating out of the slower corners at part throttle, I could not detect when the second set of injectors had joined the party as the throttle opened, so as far as I can tell on the track, their function is seamless. The overrev capacity came in handy for a couple areas around the track, giving me the option of holding onto a gear when I couldn’t reach the shift lever, or when it was better to delay the shift for a smoother drive.

There is a fast left-right transition in the infield that highlights a motorcycle’s ability – or inability – to quickly change direction at high speed. It is one of my favorite parts of the course, and the 600RR liked it a lot, too, scything its way through this section almost like it wasn’t there. Flick, flick – next, please – and there never was any unrest from the suspension or any indication of chassis windup.

With a strong, short burst of throttle out of the left/right to help bring you out to the edge of the track, you’re setup for the double-apex right that leads you onto the infield straight past the pits. As you dive for the first apex, you’re on the brakes moderately, and then quickly back on steady throttle between the apexes.

This is a fairly long corner that has the bike on its side for a while, and you can start your drive ridiculously early, thanks mainly to the Unit Pro-Link suspension, which in fact does what it has been designed to do, (that is, enable the rider to open the throttle earlier than is normally possible). Well before the second apex comes, you’re hard on the throttle and getting ready for the next gear.

At the end of the infield straight, you’re braking for turn one, which has some wavy ripples at the entry. I could feel the bike move around on its suspension a little but the bike never strayed off the chosen line.

Turn two is a medium-speed corner that you enter tight, then drift out a few feet at the middle of the corner to setup for a very late apex. As you’re doing this, you’re opening the throttle. Even with the bike leaned way over and accelerating, it tracked perfectly and finished the corner exactly as you intended. Other bikes I have ridden, even after extensive setup time, have had a tendency to run wide under similar circumstances, needing more steering input at the bars to maintain the line. Not this one!

Turns four and five are treated as a single, double apex left-hander. At the entry is a sizeable bump that (on other bikes) may have the rider looking for an alternate (and possibly slower) line, but the RR’s suspenders did a fair Houdini impression by pretty much making it disappear, even though you were told it was there.

Railing through the long left-hander leading to the front banking, I found myself grabbing two quick upshifts before heading for the second apex, the same as the left-hander that leads to the back straight. This allowed me to avoid a shift right at the transition to the banking. Although the engine was in the neighborhood of 7500rpm, I was able to open the throttle way early and it still pulled with authority. At the end of this section with the OE rubber, I was seeing 168mph, and with the 208GPs, the reading dropped to 159mph. Regardless of the speedometer’s schizophrenic readings due to differing tire diameters, I knew I was in the neighborhood of 150mph by the time I reached for the front brake lever.

Dropping in from the 12 degree banking (I know – that ain’t nothin’ to you Daytona racers) into the infield, there is a harsh transition from the banking to the flat infield. The suspension soaked this up without drama and settled quickly, which allowed me to maintain entry speed and setup easily for the left-right chicane. Part of that is down to suspension, but much of it is due to the chassis’ stiffness. And having the heavy stuff (that includes you) at the center, near the roll axis, it virtually pivots on the CG, making such transitions almost non-events.

All through the day, the transmission action was light, smooth, and slick and I never missed a shift. You can upshift just as easily without the clutch, with the next gear picking up where the last one left off with little delay. The clutch felt the same as the F4i’s, that is, a light pull with smooth engagement.

Four sessions went by all too quickly in the afternoon, with Dunlop spooning a second set of 208 GPs on my bike after two of the four rounds. Fresh tires kept another variable in check. No sense in chasing a negative handling trait if you’re on worn tires. Big thanks to Jim Allen and Dunlop for providing the outstanding rubber.

What about the bike can I pick on? The list is extremely short, and I could be accused of nitpicking, but a moment’s thought brings me back to a couple of items. First, the brakes. Although remarkable in their consistently high performance and ability to handle the extraordinary demands of track duty, they can be improved. Stainless steel lines and your favorite set of brake pads will have your triceps in shape in no time. That brings me to the second item – fork springs. They quickly showed they are not quite up to the punishment I gave them. I altered my braking technique and adjusted the damping to compensate, but it wasn’t the ideal solution. In this case, it is better to change the spring, than it is to change the riding style. If not a new set of springs, then raising the fork oil level a few millimeters and adding a little more compression damping should get you by for track days.

That last paragraph shouldn’t present serious issues for the typical 600RR buyer, though, as these items – and a few more – typically are exchanged for aftermarket replacements by racers and track day regulars.

Honda proclaims the 600RR the most technologically advanced sportbike they have ever produced. After riding it, Honda has not packed the 600RR with technology for technology’s sake, as the bike works extremely well. Honda plans to have them in dealer showrooms by March, with an MSRP of $8599. For further details and specifications, visit Honda’s website.