Yamaha YZF 600R Thundercat

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initially launched as a sports A-imachine, but has remained successful in a different, sport-touring role after being superseded by more advanced designs.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.