2006 Suzuki GSX-R 600 & 750

I was thinking it even before Kevin Schwantz put it into words: "Man, wait till you ride the new 750," the 1993 500cc world champion said on the eve of the Suzuki GSX-R600/750 press intro. "It feels exactly like the 600, only faster."

Pause for a brief moment of silence for the late, unlamented 750cc class. Where once the three-quarter-liter category formed the backbone of international Superbike racing (see sidebar, page 58), it has now almost completely vanished, thanks to the marketing arms of the major manufacturers anxious to race on Sunday what they sell on Monday--the exact opposite of the timeworn adage. That's a pity because, in my humble opinion, 750cc is the perfect size for a motorcycle engine.

Apparently, I'm not the only one who feels that way, because whether we realize it or not, the market has been creeping back toward 750s recently; witness the 636cc Kawasaki ZX-6R and Triumph's Daytona 650 and 675. So maybe instead of thinking of the GSX-R750 as being in a class of its own, we should view it as an even larger version of the GSX-R600--a sort of super-middleweight. Because this year more than ever, that's exactly the case.

Flash back to the late '80s, when Suzuki's air-/oil-cooled 600, 750 and 1100cc sportbikes were based on the same engine cases. These were the days before the GSX-R600, when the humble Katana represented Suzuki in Supersport racing (which didn't stop Yoshimura's Doug Polen from winning the '88 AMA title on one). When Suzuki finally produced a proper GSX-R600 in 1992, it was a downsized version of the then-new liquid-cooled 750 ... "and I think it weighed 10 pounds more," joked Suzuki's Motorcycle Planning Group Leader Tak Hayasaki at the '06 intro. Now, the importance of Supersport racing dictates it's the other way around.

It's always entertaining when an engineer from one of the Japanese OEMs gets up in front of a room full of journalists to detail the inner workings of his latest project in English. But we snickered more than usual when hapless Toshikazu Yamaoka explained that the concept of the GSX-R750 was to be the "top performer"--not because as the sole surviving 750 it wins by default, but because his co-worker Norihiro Suzuki had said the exact same thing about the GSX-R600 barely a half-hour earlier! Fortunately, that was the extent of the pair's redundancy as they presented refreshingly concise overviews of their respective models.

The 2006 GSX-R600 and 750 were developed by the same team, which defined four goals: 1. Emotional styling with superb aerodynamics and more functional electrics; 2. Higher engine performance; 3. Smoother deceleration; and 4. Outstanding cornering performance.

Job one was downsizing the engine--and then upsizing it. The engineers started by stacking the transmission shafts to shorten the engine and reducing the pitch between the cylinders to narrow it. That left insufficient room for the 750's larger pistons, so its bore was reduced by 2mm to 70mm and its stroke lengthened by 2.7mm to 48.7mm, taking the bore/stroke ratio from 1:565 to 1:437. That smaller bore in turn reduced the space available for the titanium valves, which was further reduced by the valve stems being tilted more upright to create a shallower, higher-compression combustion chamber. That meant reducing the size of the 750's exhaust valves by 1mm to 23mm. Of course the longer stroke would have made the 750 shake, so the engineers added a balance shaft like on the 1000. Topping it all off is a new fuel-injection system with twin injectors, the throttle bodies measuring 40mm on the 600 and 42mm on the 750. Although Suzuki doesn't publish power figures, the engineers reported that the '06 600 produces 5 more horsepower than last year's model and the '06 750 2 more, which should equate to approximately 110 and 130 bhp at the rear wheel, respectively.

Reducing the physical size of the engine opened up a world of possibilities for the chassis, and the engineers capitalized on every one. They made the frame narrower so it wouldn't feel as wide between the rider's legs. They made the gas tank narrower and shorter, which let the rider scootch farther forward. And they made the seat lower, which let the rider tuck in tighter while giving shorter riders firmer footing. Last but not least, they gave both bikes a new exhaust system, with the large, heavy muffler positioned under the engine in the interest of mass centralization. Maybe Erik Buell had it right after all?

That helped maybe a little the next day, when we did three 20-minute sessions on the 600s. Sitting on the bike for the first time, I noted that it felt a lot like the 1000 after which it was patterned, a tad smaller physically, but no less roomy. Easing down pit lane for the first time, I was surprised how well the engine ran down low in the rev range. It pulled cleanly away from a standstill with just 2000 revs showing on the analog tach, with no clutch slippage required--unheard of on a 600.

We did two slow laps behind a factory test rider to get some heat in the stock Bridgestone BT014 tires before each session, then returned to pit lane to be flagged off at 10-second intervals. Given the intense rivalry between moto-journalists, it was like watching the start of the Isle of Man TT as each rider roared off in pursuit of the one in front of him.

I took it fairly easy until multi-time WERA National Endurance Champion Sam Fleming of Roadracing World/Army of Darkness fame drafted past me on the front straight. Then it was on, and as our pace increased, I had to agree with what Sam said afterward--that he was impressed how easy it was to hop on what was an unfamiliar bike and ride it so hard, so fast. Granted, he's been racing GSX-R600s for years, and this latest version has a familial feel.

Compared to last year's model, the '06 600 has smoother low-end throttle response that lets you crack open the throttle sooner exiting a corner without worrying about unsettling the chassis. Though the meat of the power doesn't come until beyond 8000 rpm, the engine runs cleanly at lower revs, letting you short-shift and pull a taller gear through a corner to reduce wheelspin--especially useful when the tires are worn near the end of a race or track day. That proved useful on the short chute between the Honda Hairpin and Siberia, and between the tight downhill MG corner and the long uphill Turns 11/12 that end a lap at Phillip Island. Speaking of gears, both the 600 and 750 have a digital gear indicator this year, like the 1000, which proved especially useful on the smaller bike. They also have a programmable shift light, which would be more useful if it were moved up higher on the dash and not hidden behind the clutch cable. Rocketing down Phillip Island's half-mile-long front straight on the 600, I had to pay close attention to the tach needle to shift at the power peak, which came a tad shy of the 500-rpm-higher, 16,000-rpm redline. The LCD speedo was set in metric mode the first day, and I routinely saw 250 kph (about 155 mph) before braking (slightly) for Turn 1, named for five-time Aussie MotoGP Champion Mick Doohan.

Speaking of braking, both GSX-Rs have 10mm-larger 310mm rotors this year that work with the Tokico radial four-piston calipers and radial master cylinder to provide superb feel and stopping power. Also helping here is the new slipper clutch, which lets you crowd your downshifts impossibly close to corners, and even bang more than one at a time without having to worry about the rear tire chattering when you release the clutch lever. Revised steering geometry with .5 degree more rake and 4mm more trail improve stability while trail-braking, with no adverse effect on turn-in; if anything, the new bike tips in even better than before. Handling is above reproach--light yet stable even at triple-digit speeds, and there's plenty of cornering clearance even with the adjustable footpegs (hallelujah!) set in the standard middle position. Understandably, the fork and shock springs felt a tad soft for my 6-foot, 200-pound frame.

That wasn't an issue the next day, because the 750 boasts upgraded suspension with stiffer springs, both high- and low-speed compression damping adjustments on the piggyback shock reservoir, and a friction-reducing carbonized titanium coating on the fork sliders. I could feel the improvement from the first lap, as the 750 pitched less under braking and squatted less under acceleration, letting me ride much more aggressively. Beyond that, though, the only real difference was engine power--and man, what a difference. With the new engine's longer stroke, you'd expect it to have a lower redline, but it was in fact raised 600 revs to 15,000 rpm.

Suzuki introduced the 2006 GSX-R600 and 750 to the world press at Phillip Island, Australia, this past February, two weeks before the scheduled World Superbike races there. I'd never been to the Island before, but I happened to be at Willow Springs the first time Australian Anthony Gobert tested there, and he pronounced the place "like Phillip Island without grass or an ocean," which is as apt a description as you'll hear anywhere. Both venues are blazingly fast and flowing, with comparable elevation changes, though the Island is a lot less bumpy and infinitely more scenic; it's hard to concentrate on your riding when you can see waves crashing on the cliffs in the distance. Fortunately, I was able to "learn" the racetrack by driving a go-kart on a scale replica of the circuit located on the premises.

With 20 more peak horsepower than the 600, the 750 felt loads faster in a straight line, and with the speedo set in American mode the bike flirted with 170 mph on the front straight. But it was the increased midrange power I noticed most. As noted, there are two places at Phillip Island where short-shifting pays dividends, and while you had to get it just right on the 600 or risk bogging the engine, the 750 pulled cleanly through every time. Short-shifting proved especially beneficial during the second session, when the sun came out from behind the clouds, raising track temperatures from 80 to 100 degrees and reducing available traction from the stock Bridgestone BT014s (which have a slightly different construction than the ones on the 600). Chasing transplanted Aussie Paul Carruthers of Cycle News around the racetrack, I experienced a rash of momentum slides before deciding that discretion was the better part of valor and backing off. Carruthers pressed on, and after he nearly tucked the front end in 100-mph Turn 2 and an Aussie journalist fell in the exact same place, the tire technicians opted to lower air pressures from the standard street settings of 34/36 psi to a race-spec 31 psi at both ends, which worked much better.Between the lower tire pressures, two turns of spring preload and a half-turn of high-speed compression on the shock, the 750 was on rails in the last session, and I just managed to hold off my nemesis-for-the-weekend Fleming--never mind that he started 10 seconds behind me. Unofficially, my best lap time over the two days was a 1:48 and change--"only" 16 seconds off the long-standing World Superbike lap record set by Troy Corser after the circuit was repaved in 1999. Funny, it felt fast ...

Snail's-pace lap times notwithstanding, at the end of our two days' testing everyone was thinking the same thought: The new GSX-R600 is a nice enough motorcycle, but why would you choose it over the 750, which works better in every appreciable way?

That Schwantz fellow may be onto something ... MC

No parking: The totally redesigned 2006 GSX-R600, out of its element in repose in a Melbourne park. Suzuki had only blue/white examples at the Autralian press intro, but it's also offered in red/black, black/gray and silver/white. Price is $8799 - just $600 more than last year.