Cycle News is a weekly magazine that covers all aspects of motorcycling including Supercross, Motocross and MotoGP as well as new motorcycles
Issue link: https://magazine.cyclenews.com/i/127657
1995 Yamaha YZF600RG Y? Because it's better Deltabox chassis. The dimensions of the frame have undergone drastic changes. The wheelbase has been shortened some 5mrn with the bike now measuring in at 55.7 inches. Like the YZF750, the 600 has a detachable subframe for ease of maintenance; the detachable unit also makes it easier to mount a racing seat. The YZF's rake has changed while the trail remains the same as the FZR The YZF now boasts 25 degrees of rake and 3.8 inches of trail, and also features a more forward-oriented weight bias. Suspension is handled by a 41mm conventional front fork that offers preload adjustability. The traditional Yamaha monocross rear suspension features both pre-load and re bound dampi ng. Th e YZF600 uses 298mm d u al d iscs (fo u r p istons) up fr ont and a si ngle 245mrn disc (two-piston) in the rear. The YZF600 is fitted with read y-torace wheels: 3.5 x 17-inch in the fro nt and a beefy 5 x 17-inch rear wheel. Both wheels are constructed of hollow alumin um. Although our YZF600 im p ression was based entirely on our day a t the race tra ck, we came away impressed with wha t we feel will no t only be a betBy Paul Carruthers Photos by David Dewhurst ake no mistake abo ut it - the 1995 Yamaha YZF600R is not a re bo rn FZR600 - ju st ask Jamie James and Colin Edwa rds II. If yo u th ink Yamaha co uld have talked these two into racing dated FZR600s at Daytona, think again. It ha s been alm ost two years sin ce Yamaha has tasted success in the ultra competitive 600cc Supe rsport class a t an AMA Nat ional. In August of 1992, the late Larry Sch warz bach won at the MidOhio Sports Car Course. Nowadays it's a ra rity to see a Yamaha on the grid, muc h less in the top 10 - but tha t's about to change. Edwards and Jam es d on't race to finish outsi de the top 10. The ulti ma te test for th e all -new YZF600 will come on Sunday, March 13 at Da ytona In terna tional Sp eed wa y . During the AMA /CCS warm-up events on March 5-6 at the Speedway , James and Ed wards tested, but d idn 't race, the new bikes (see sidebar). Members of the motorcycling press were given the opportunity to test rid e the YZF600s at the end of January in a session at Lag u na Se ca Race wa y in Monterey, Californi a. Threatened with d ea th if wo rd leak ed ab out the new Yamaha before March, we were soon off and running at Laguna Seea - the site of the United States Grand Prix. On e of th e first th ings yo u notice about the YZF600 is just how similar it lo oks to its big brother, the YZF750. That's because it uses the same seat, gas tank, ins tru ments, rear view mirrors and h eadli g hts as the YZF750. A scaled down 75O? Not at all. More importantly, the YZF600 is not just a revamped FZR6oo. The engine is completely new. The existing 599cc four-cylinder engine wa s too heavy and too slow, so Yamaha engineers redesigned the engine with three goals in mind : to improve performance, decrease we ight and improve reliability. To start things off, Yamaha bumped M The 1995 Yamaha VZF600 at speed and parked. The bike Is not a scaled down VZF750 0r an updated FZR600 • It's all new. the bore up from 59mrn to 62mrn while decreasing the stro ke from 54.8mm to 49.6mrn, and the cylinder walls now feature ceramic-composite pl atin g. The four-valve-pe r-cyli nder head has also undergone changes, with the ports differing in both size and sha pe. The ports are now oval, rather than ro un d, and have decreased in size from 37.5mm to 34.5mm. The combustion chamb er has al so decreased from 12.3cc to l1.2cc, with the valve angles narrowing · intake from 18 degrees to 17 degrees; exhaust from 18 degrees to 16.75 degrees. Compression stays put at 12.0:1. Yamaha shredded some engine weight via the crankshaft . While the FZR600's crank sha ft we ighs 15.6 pounds, the YZF's as sembly weighs only 13.9 - a loss of 1.76 pounds. In addition, Yamaha has given the YZF a beefier clutch - up 5mm from 115 to 120mrn - and it also now uses a push -rod bearing for smoother shifting. The engine is fed via four 34mrn sem i-downdraft Keihin carburetors. A major change is the angle in which the engin e sits in the chassis. While the FZR600's e ngine w as situ ated at 45 degrees, the cylinder angle of the parallel fou r in the YZF now s its more up right at 35 degrees. . While the FZR600 used a four -in toone exhau st, the YZF gets a four-twoone system with the actual exhaust pipe size getting bumped up 3.2mrn - and no EXUP. Usually used to increase midrange, Yamaha engineers felt the YZF600 had enough punch in the mid dle to do without the extra cost and weight of the system. Although the frame is still constructed of steel, the YZF600 now uses the e ngi n e as a stress member of its te r race bike - bu t also a better street bike. Th e en gin e shoul d provide power that's on par with the rest of the 600cc Supersport class . Manageable at even low rprns, the powerplant really comes alive in the 6-6500 rpm rang e, and continu es to do an admirable job of making power all the way to its 13,000 rpm redline. The climb from Laguna Seea's tum six to its famous Corkscrew provides a very good test for a middleweight sportbike, and the YZF scales the hill with the best of them. The Corkscrew itself then hands out a serious test of the bike's flickability. Again, the YZF came out a winner. Negotiating the left-to-right transition in the Corkscrew was a simple process on Yamaha's newest 600. It's hard to really tell just how good the suspension will work on rough com-