The 2005 R6’s power delivery was massaged in an effort to improve top-end power without hurting things in the bottom or mid-range kevin the wing

A non-riding friend recently asked me why I get so excited every year about riding the newest sporting machinery. After all, how much of the newfound performance could I, as a mere mortal and not a professional racer, actually use—either on the street or the track? Initially, his question stumped me. Since he isn't a rider, I didn't think he could relate to the sheer techno-geekery of seeing how sportbikes are relentlessly refined and redefined from year-to-year. Stats and figures only mean something if you have a way to parse them. Ultimately, the only analogy I could come up with was one of wine tasting. His question seemed to imply that once you get to a certain level of quality, why bother tasting anything new? Most people don't have the discriminating palate to really quantify the differences between this year's Beaujolais Nouveau and last year's. Still, people get excited every year when they are released. That seemed to satisfy him. Since 600cc sportbike development is racetrack-driven, only the best riders will truly be able to fully exploit the annual upgrades. However, on the street, even those of us with less advanced palates can still experience the subtleties that set this year's model apart from last year's.

For 2005, Yamaha heavily revised the R6 to give the racing segment of its sales what they've wanted for years: an inverted fork. While this is an obvious change, it also was the driving force behind many not-so-obvious ones. How did they affect the well-known character of the R6? The R6 has always been credited with quick steering. However, sometimes the feel was a little lacking at the limits. To address this limitation, Yamaha fit a 41mm inverted fork on the '05 R6. While they were tinkering with the front end, they decided to (finally) slip a 70-series front tire on the rim so that riders who wanted to put the latest sporting rubber on their bikes wouldn't have to adjust their fork height to account for the taller profile tire. Sounds like an easy change, right? Well, these additions to the R6 also prompted several more. First, having a stiffer front end means that the entire chassis, not just the front, experiences more stresses. So, in order to balance the rigidity of the frame front and rear, its bottom cross-member needed to be beefed up. Yamaha's Controlled Fill (CF) diecasting process allowed for a 50-100 percent increase in thickness where the shock's relay arms mount. The relay arms were also reshaped to give a more progressive lever rate (from 9.6 to 12 percent) as the swingarm is compressed. The new relay arm also increases the rear ride height by 10mm to match the increase in the front-end height. The front and rear spring rates were upped slightly (six percent in the front and five percent in the rear) to give a firmer ride and take advantage of the new feel in the front end. Although the developers tried to keep the internal damping rates the same as the '04 model, the recommended standard damping settings have been modified to account for the stiffer spring rate and increased rear lever ratio. Mounting old-tech brakes to the snazzy new fork would have been made all the other sporty bikes laugh at the R6, so the R1's radial mount calipers enter the mix. These four-pot Sumitomo units squeeze R6-specific brake pads against 310mm full-floating discs. Although the calipers do come from the R1, the R1 pad compound proved to be too grabby. To give the brake proper feel, a new compound was developed. Since the larger Dunlop 120/70ZR17 is heavier than the smaller 60-series tire run last year, the 12mm-larger diameter discs are 0.5mm thinner to help minimize the increase in rotating mass on the front wheel (Yamaha didn't want to slow down the R6's famed quick steering). The brake system is pressurized by the same Brembo radial-pump master cylinder as on the '04 R1 with the goal of increasing front brake feel and modulation. The combined result of the chassis changes is a bike that has a 5mm longer wheelbase of 1385 mm (54.5in.). Similarly, the overall length grew from 2025mm to 2045mm (80.5 in.). The changes in ride height also increased the rake by 0.5 degrees to 24.5 degrees. The new fork offset bumped the trail to 95mm (up from 86mm). Aside from the obviously new fork and the gold pucks on the new calipers (silver on the Raven model), the profile of the R6 hasn't changed noticeably.

Specifications: 2005 Yamaha R6

Model: YZF-R6T Retail price: $8,399 ($8,499 Raven) Engine type: 600cc, liquid-cooled, DOHC, inline four Bore x stroke: 65.5 x 44.5 mm Compression ratio: 12.4:1 Carburetion: EFI Ignition: Digital CDI Transmission: Constant-mesh, 6-speed Suspension: Front: 41mm inverted telescopic fork with adjustments for preload and compression and rebound damping, 4.7 in. travel Rear: Single shock with adjustments for preload and compression and rebound damping, 4.7 in. travel Brakes: Front: Dual 310mm floating discs with radial-mount forged 4-piston calipers Rear: 220mm disc with single piston caliper Tires: Front: Dunlop D218F 120/70-ZR17 Rear: Dunlop D218 108/55-ZR17 Overall length: 80.5 in. Wheelbase: 54.5 in. Rake: 24.5 degrees Trail: 3.7 in. Seat height: 32.3 in. Dry weight: 357 lb. Fuel capacity: 4.5 gallons Colors: Team Yamaha Blue/White, Rapid Red, Raven

Yes, the leading edge of the fairing lower has been reshaped to make more room for the bigger rubber and some other small changes were made to the ram air intake and the inside of the fairing lower, but the 2005 R6 looks essentially the same as the '03 and '04 models. As with every update to a sportbike, the R6's power delivery was massaged in an effort to improve top-end power without hurting things in the bottom or mid-range. The engine retains the same 65.5mm x 44.5mm bore and stroke as the '04 model. The cams, timing, compression ratio—in fact, the entire engine is unchanged (with the exception of substituting two smaller fans for the one large fan as required by space constraints with the larger front tire).

This year, Yamaha chose to focus on the intake system for the new ponies. First, the EFI throttle bodies increased from 38mm to 40mm for more poop in the top end. Rather than switching to R1-like servo-controlled secondary butterflies, Yamaha chose to stick with the vacuum-operated slides that have worked so well in the past. The fuel regulator pressure was bumped 7 psi to 48 psi to meet the new fuel delivery requirements of the wider throttle bodies. Inside the airbox, the air funnels grew larger in diameter to fit the new throttle bodies, but they were also reshaped to optimize "air intake pulsation efficiency." The funnels for cylinders two and three were shortened by 5mm to 30mm. As with the '04 model, the center and outside cylinders received velocity stacks of differing height, with the outer stacks staying the same as last year at 15mm.

Yamaha claims that the mid-range power was maintained by this reshaping of the funnels. The injector map and ignition timing were also changed to accommodate the changes in the EFI system. Yamaha gathered a motley group of journalists for a ride on the famed Angeles Crest Highway to give us a chance to sample the improved 2005 R6. Unfortunately, plans don't always go...as...uh...planned. Several days of rain prior to the introduction ride left the Crest closed and our group of riders in search of clean roads (for those unfamiliar with Southern California's geology, rains invariably wash tons of sand and gravel off the scrub brush-covered hills and onto the road surface). While the poor road conditions prevented all-out performance riding, we were able to get a good feel for how the '05 R6 will fare as a street bike. The R6's characteristic quick turning is still alive and well—even with the larger front tire and more rotating mass. Turn-in is precise and immediate, as is the ability to change lines mid-corner, which allowed me to thread my way through the clean lines on the dirty roads. Additional steering effort is required, most noticeably in side-to-side transitions in linked turns. While you may be aware of the increase in effort in these situations, the nimbleness and flickability of the R6 remains unchanged. I'll leave it to the racers to decide if the bike has better feel at the limits that I won't approach on the street. The new spring rates result in an all-around firmer ride. In town, the '05 R6 feels taut, but not harsh. Ramp up the speed, and the bike feels more planted than the previous models. The chassis feels more stable and less affected by road irregularities. In fact, the faster you ride, the happier the suspension feels.

High-speed sweepers with rippling bumps left the bike unfazed. Sharper-edged bumps were absorbed with minimal upset to the chassis. Only on an extremely rough section of road did the front-end feel even the slightest bit ornery with one big wag of the clip-ons after an ill-timed throttle input momentarily conspired with the road surface. My 175-pound weight (sans gear) may have been the sweet spot for this bike. One 140-pound rider said he felt that the suspension was a little on the stiff side, while a rider who was around my weight but with a more aggressive riding style said he'd bumped up both the preload and compression damping to satisfactory results. Again, the faster you ride this bike, the more it seems to like it. The new brakes are quite deceptive. The first time I applied them at speed, they didn't feel terribly strong. However, this was due to the linearity of their power. Quite simply, the more I pulled on the lever, the better they worked. In dirty riding conditions where speed sometimes needed to be modified mid-corner, the lack of progressiveness in the braking made it much easier to give just the right brake input required. Similarly, my confidence trail-braking into unknown corners increased as a result of ease in modulating the brake application. The Dunlop D218 tires exhibited minimal tendency to stand up under braking. For the most part, the intake modifications made for better power delivery. The mid-range felt just as strong, if not a hair peppier than the previous model. When running the engine through the rpm range, the top-end power felt noticeably stronger and more willing to spin up than before. The larger throttle bodies clearly help in this regard. However, transitioning from off-throttle to on at 10,000 rpm or above usually gave an abrupt hit that one wouldn't expect from an EFI bike with CV slides. This problem appeared in the '04 R6 but was not an issue in the '03 model (which, in the interest of full disclosure, I should mention that I own). The hit was abrupt enough that it felt almost like driveline lash, and I even checked to make sure that my chain was correctly adjusted at one of the stops on the ride. While the abruptness wasn't a major problem, it did force me to direct more attention away from other tasks to my throttle hand than I would have liked. Overall, I'd say that the 2005 R6 is a step up from the previous models. The new suspension and brakes work well.

The new 70-series front tire will make swapping rubber for track days a much easier affair. And more power is always good. Whether these changes will translate into another Supersport championship for Team Yamaha remains to be seen, but with Yamahas making up 51 percent of the race entries in the AMA Supersport class, you can bet there's some serious interest in what this new iteration is capable of achieving.

If you're in the market for a new 600cc sportbike, you owe it to yourself to take a look at the R6.