Cycle News - Archive Issues - 2000's

2003 Honda CBR600RR The CBR600RR's completely new engine owes a lot to the RC211 V MotoGP bike and uses new technologies that make the bike the most technologically advanced streetbike that Honda has ever built. Not only was the liquid-cooled 599cc inline four designed to perform its duty as the power plant, but it has also been asked to perform additional duties such as contributing to the bike's theme of mass centralization. One of the key design goals that project leader Hiroyuki Ito and his team set out to accomplish was to make the motor considerably more compact. This, combined with other changes to the chassis, would allow them to put the weight of the bike exactly where they wanted it, in an effort to optimize the bike's handling. By stacking the transmission's mainshaft 48.4mm above the crankshaft's centerline, they were able to move the countershaft closer to the crank in a triangulated layout. This allowed them to move the swingarm pivot 30mm closer to the crankshaft, resulting in a much more compact package. To take it a step further, Honda rotated the exhaust ports 30-degrees downward to allow the header pipes of the exhaust to hug the motor more closely, in tum making space to move the motor forward in the chassis an additional 9mm. An additionnal benefit was that the team was able to lengthen the swingarm due to the extra space the compact motor provided. Another key to making the motor smaller was moving the crankshaft-mounted starter gear from its traditional position on the left to the right side of the engine - this reduced the width by 21.5mm and gives the bike three more degrees of bank angle. The RR's motor shares the same bore and stroke dimensions as the F4i's (67 x 42.5mm) because the engineers determined that those would still be the best numbers for the bike. But that is where the similarities stop. The Programmed Dual Stage Fuel Injection (PGM-DSFI) system is technology taken from the RC211V. It's a really cool system, because it combines four Denso 40mm throttle bodies - with one injector per body - with four more shower-type injectors that are located above the velocity stacks in the ajrbox. The bike only uses the throttle-body injectors when the engine rpm is below 5500rpm, and then the other four kick in for high rpm fuel delivery. According to Honda, at 15,000 rpm, there are only four milliseconds for the fuel squirting out of the lower Denso injectors to vaporize, and that's just not good enough. That is why the second bank of shower injectors was added. When you look into the airbox, it's really amazing to see how far the shower injectors really sit above the velocity stacks (I'm gueSSing four to five inches). This was done because the added height gives the fuel mixture more time to vaporize before it enters the intake tract and combustion chamber, for better combustion. In order to control all of this, Honda needed to increase the processing capacity of the bike's computer, so a new ECU was fitted with a 32-bit processor. Feeding air into the airbox was another criterion that needed improving. The Dual-Stage Air Induction system has new larger ducts on the fairing to get the cool air into the larger 15-liter air box. An interesting note is that the ducts themselves have holes punched in them, because engineers discovered that it improved the steering a bit by reducing drag at that point on the bike. The RR's new redline created a lot more reciprocating mass, so the engineers had to redesign the pistons, rods and pins to reduce their weight. The new forged slipper pistons are now 14 grams lighter each, while a new tool-steel pin is used on each piston to shave off an additional 8 grams. The new carburized con-rods feature a lighter nutless design, which saves 12 grams per rod. This may not sound like much, but that adds up to a 34gram saving per cylinder, and at 15,000 rpm, that's a big deal. The intake valves are larger on the RR at 27.5mm as opposed to 26.5mm on the CBR600F4i. There are two lighter valve springs per valve to keep lift in check. A new dual-pivot cam-chain tensioner keeps the chain from whipping at high rpm. An additional guide overlaps the main guide to provide additional pressure on the chain. Honda calls the new exhaust system a center-up design. As I mentioned earlier, the exhaust ports are rotated 30 degrees downward to keep the headers closer to the motor for compactness, then the pipe runs underneath the motor and then up and back under the rear seat. The center-up design not only looks trick, but it also improves the bike's aerodynamic efficiency and gives it more ground clearance. No more decking the can on the pavement like on the F4i. Honda claims that the new CBR600RR makes 117 horsepower at 12,500 rpm and 49.9 ft.-Ibs. of torque at 10,000 rpm. I'm not sure what that will translate to on our dyno at the rear wheel, but I'm guessing around 105 hp, which would be class leading, so wait for our upcoming shootout, and all these questions will be answered. of the banking and rounding the next long left, I realized that I was ripping through two gears in short succession. After I thought about it for a while, I came to the conclusion that I couldn't recall a 600 that had such a voracious appetite for revs in the top of the powerband. One of the coolest things about riding the bike on the 16 FEBRURY 5,2003' eye I track is that the bike makes its peak horsepower at 12,500 rpm, but the redline isn't until 15,000 rpm. This means that you have 2500 rpm of overrev to play with jf you're in a position that is difficult to shift in, or if you just want to save making another shift all together. Midrange power feels very 600-like, not a ton of • o.""s This is the view of the dash, which has all of the info you could ever need. torque or power forcing you to keep it above 9000 rpm if possible. The RR's fuel-injection system definitely does its job in the upper revrange, but there is just a tinge of hesitation from the system in some of the slower corners as the throttle is picked up, but it's nothing that gets the bike out of shape. As you will read in the engine sidebar, the new Dual Stage Fuel Injection System is technology taken from the RC211 V MotoGP bike. LVMS has plenty of places that require hard braking, and the brakes didn't disappoint. They aren't the best brakes that I've sampled, but they do their job very well; they just seem to require a longish amount of lever travel to achieve the desired amount of power. Combined with the new forks, I never had any problems braking all day. The front end felt stable, while the rear end stayed perfectly planted with the longer rear swingarm keeping the rear tire in solid contact with the road. The RR's transmission was beautiful all day_ 1 never missed a shift that 1 can recall, and the thing shifted as smooth as silk. The ratios seem perfectly spaced for the track and should be just as good on the street. I was super bummed when the checkered flag flew for the final time of the day because I was just starting to get really comfortable with the track. The RR was perfect all day, literally waiting for me to get my head together and ride a little harder. By the last two sessions I felt like I was making the bike work a bit, but only A standard lock like a Kryptonite Ulock will fit under the passenger seat.

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