Yamaha YZF 600R Thunder cat

Like many bikes, Yamaha's Thundercat was initially launched as a sports A-imachine, but has remained successful in a different, sport-touring role after being superseded by more advanced designs. First seen in 1996, the Thundercat replaced the elderly FZR600R and was an immediate success. Its inline-four engine was based on the FZR, but heavily revised for improved power and torque. The frame was also similar to the FZR, using a steel Deltabox design, together with an aluminium swingarm. The result was a bike that was heavier and less focused than its predecessor, but with more modern performance.

The styling is very distinctive. The aerodynamic single headlight nosecone is similar to the Thunderace 1000, also launched in 1996, and incorporates a ram-air induction system which increases the engine's output as speed increases. Also shared with the Thunderace are the four piston front brake calipers, manufactured by Sumitomo and shared with many recent Yamaha models. These brakes, which were a revelation to many riders in 1996, are still among the best performing brake components on the road.

The conventional suspension setup is soft for a sportsbike, but is still capable on road and track. Many 600 Supersports racers campaigned the Thundercat, with remarkable success, including at world level (Vittoriano Guareschi finished second on a Thundercat in the 1997 WSS championship). The suspension's built-in adjustment front and rear can improve performance, but aftermarket improvements can pay dividends for track use.

Equipment levels are sufficient rather than extensive, and the Thundercat's sports-derived dashboard is less comprehensive than some all-round competitors. Having said that, its 19-litre (4.2 gal) fuel tank gives an extended range, and the spacious dual seat offers comfort for many miles.

YAMAHA'S REVISED AND REFINED YZF600R OFFERS NUMEROUS facets for admiration. First glance will become a stare because Yamaha's stylists have finally found a look that works for their midsize sport bike, from the uniquely shaped, wind-tunnel-tested fairing complete with ram-air scoop to the tasteful and, dare we say it, classy paint work.

The same strong YZF chassis that took Jamie James to the '94 AMA 600 Super-Sport championship is updated with all-new cartridge front suspenders matched to a recalibrated shock, while the ram-air scoop feeds pressurized air to carburetors measuring two millimeters larger than last year's mixers. The power increase we noticed from the seat was blunted amazingly well by the YZF's stunning front stoppers, a beautiful set of one-piece, cast-aluminum calipers that add whoa to the YZF's show-and-go. After two months of tireless flogging, touring and track-testing, Yamaha's YZF600 threatens to be the best 600cc street bike Sport Rider has tested.

Yamaha's positioning of the '97 YZF600 depends upon your perspective. Racers will claim Yamaha's target is the 600 SuperSport class, pointing to the fully adjustable suspension components and reciting the 88 rear-wheel ponies we saw on the Graves Motor-sports Dynojet dyno, then referring to the 11.48-second quarter-mile and 119.8-mph trap speed as proof that Yamaha is chasing all-out performance first and foremost. Street riders, however, will find substantial proof that Yamaha's sights were focused on their interests, fingering the same suspension adjustability that can adapt to differing roads and loads and wrapping their argument around the YZF's real-world ergonomics and outstanding wind protection from the all-new fairing. Each faction will find strong points to support its views, but as the Sport Rider staff came to know our black and silver 600 m6re intimately, we found ourselves convinced that Yamaha aimed its revised YZF600 more at the real-world street rider than the relatively few racers who will make the jump to the track.

The bare-bones look of many repli-racers just isn't apparent in Yamaha's latest 600. In fact, the YZF's fit and finish are significantly updated over last year and put the bike on par with Honda's benchmark CBR600F3, as we discovered when stripping the bike in the studio. The styling received significantly more positive comments than the flash-boy F3 graphics, or last year's YZF for that matter, and no one can deny the importance of styling in the pride-of- ownership debate.

Yamaha's YZF600R appears 750-sized and offers 750-size ergonomics as well, with excellent legroom for those under 6 feet 2 inches tall and a relatively short reach to the handlebars mounted just above the upper triple clamp. While the seating position isn't significantly different from that of the other 600-class competitors, the wind protection from the revised fairing is certainly the best in the class, with a smooth plane of air coming off the sculpted windscreen that is bracketed by wide ABS-plastic borders, similar to Biaggi's Aprilia racer. You might not notice the improvement in a short ride, but we certainly appreciated the air management during our two months of testing. Last year's comfortable two-piece seat is now a single unit and is good for most hauls, though some felt it a bit too soft for day-long rides. The YZF spent few if any nights in the SR garage and was a popular ride for weekend duty.

The YZF extracts no penalty for its performance in day-today living. Cold starts need only the smallest enrichener settings, facilitated by the bar-mounted lever, and carbure-tion was marred only by a slight off-idle lean stutter that muddied throttle response below 2500 rpm. Last year the YZF mixed gas and air in a set of 34mm Keihin carbs, but the '97 wears 36mm units that are better suited to the engine, not just helping to produce more power, but offering cleaner jetting choices as well. The street-based ergonomics are backed by a street-based torque curve that peaks at only 9500 rpm with 45.9 foot-pounds of torque, meaning you don't need to rev the rings out of it to squirt ahead in traffic; we found ourselves short-shifting the YZF just as if it were a 750 or 900. The bike shifted nicely prior to our dragstrip testing, but a few abusive launches took an early toll on the clutch, affecting not just leaving a stop sign, but the bike's ability to shift smoothly as well.

First-time sport-bike buyers might be surprised to find no centerstand, but that, along with terribly weak horns, is the norm rather than the exception. Unfortunately, Yamaha ditched last year's electronic reserve switch in favor of a single low-fuel warning light that increases the fuel-level guessing game. Also, Yamaha added a helmet lock that leaves your helmet dangling against the chain side of the swingarm, which isn't the cleanest place on a motorcycle; the underseat hooks of last year are preferable.

In a word: yes. The racy blue-anodized plugs on the outside of the Sumitomo calipers signify the one-piece design of the cast-aluminum calipers, which required the pistons to be inserted from the outside. They're attractive, distinctive and 18 percent more rigid than last year's binders, bringing world-class braking to the front of the YFZ in terms of both feel and strength. Despite the YZF's relatively hefty wet weight of 485 pounds, only one finger is needed on the adjustable brake lever, no matter what speed you're traveling or how hard you need to stop. Jumping off any other bike and onto the Yamaha necessitates a mental adjustment, because you don't just grab brakes this strong without either putting your helmet through the windscreen or pivoting the whole machine into the air in a stoppie. And, yes, those are illegal.

Yamaha's componentry update isn't just confined to the front brakes, it also includes revised damping rates in the cartridge fork, focusing on a more progressive compression action at the bottom of the fork stroke. We praised the YZF's around-town ride last year, and the kudos are still applicable. If anything, the YZF seems more poised and confidence-inspiring than last year's bike, at least at street speeds. Many testers used the word "exact" in their descriptions of the light-steering Yamaha because it could be placed in the corner with precision and slight adjustments were little more than a thought away. The '96 YZF didn't care much for small, quick stutter bumps, but the suspension revisions have improved the '97's ability to deal with these small jolts. But as we'd later discover during our track testing, the chosen spring rates are biased a bit more toward comfort than performance, being a bit softer than even an aggressive street rider would choose.

The answer depends upon how you ride. If you hammer hard or ride extremely rough roads, you may find yourself running the shock and fork springs near their maximum preload, with correspondingly high rebound and compression settings. Our lighter and smoother testers had few complaints, but the hammerheads among us felt the bike a bit loose and in need of an extra moment before it settled during aggressive or bumpy corner entrances. The YZF's weight certainly hurts in this instance.

We were pleased with the mileage and traction quotient of the stock Bridge-stone tires, even at elevated street speeds. Hard-core corner chargers would be smart to look at spring upgrades and stickier skins, simple updates that would make the YZF a delightfully responsive canyon charger.

Yamaha's suspension choices that may prove marginal at the racetrack's elevated speeds make perfect sense on the pot-holed streets of the real world. (We'll pit the YZF against the CBR, ZX-6R and GSX-R for a full street and track shootout in the near future.) The '97 model absorbed sharp-edged jolts like frost heaves and cement freeway undulations significantly better than last year's YZF, the trade-off being slightly increased fork dive under hard braking, even with the preload adjusters showing only three lines. Each tester remarked on the tight, exact steering characteristics, and the planted feel of the bike at same street speeds. The standard (noninverted) fork was praised for its feedback, even on the stock tires that usually mask traction information, and everyone that rode our black beauty commented on the light, willing steering that made the relatively large 600 immediately ridable. The YZF tends to fall into the corner at steep lean angles due to the triangulated front Bridgestone, but the steering remains predictable and neutral at less radical lean angles, which translates into a bike that's easy to go quick on.

The engine really helps the first few miles of acclimation because it revs with a willingness that belies its relatively long-stroke design, which has a 62mm piston moving through a 49.6mm stroke (Honda's F3 uses a 65mm piston in a 45.2mm stroke). Theoretically, the YZF's longer stroke can limit engine rpm due to elevated piston speed, but the Yamaha redlines at 13,000 rpm, or 250 rpm below the F3. A second long-stroke theory centers around increased midrange due to more complete cylinder filling, and that theory is borne out by the YZF's willingness to pull from any rpm, with anything over 6000 rpm getting your attention and 8500 rpm serving as the take-off point as the YZF starts making some serious steam. The power flattens about 500 rpm before redline, but we can't remember a more rev-happy 600cc engine coming from Yamaha since the FJ/FZ600 two-valver. It makes every facet of riding more enjoyable, from zipping through city traffic to grabbing gears on the way up the mountain. One ride will impress you with the packaging that Yamaha has at last achieved with its YZF600.

At $7399, Yamaha has created a 600cc sport bike that breaks through the class barrier to ride and feel more like a 750, stressing streetability over racetrack performance. And that's what the majority of us do most of the time, or so Yamaha hopes by producing a package that combines a street-oriented powerband and chassis with stunning styling that says "beautiful motorcycle" not "repli-racer." Don't misunderstand, the YZF600R gets around a racetrack just fine, but it gets through daily life in the real world amazingly well.

Source  SPORT RIDER 1997