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/146704
eRIDING IMPRESSION 1993 Kawasaki Ninja Sp.:.:. :.ortb:..=ik=:-es --- m By Paul Carruthers Photos by Nick Cedar and Carruthers esson number one was simple enough: Never wear a Wayne Gardner replica helmet when you're riding around Laguna Seca. Lesson two required even less common sense: Oon't use the same braking markers on a Kawasaki ZX-ll as you just did on a ZX-7R: Less~>n three ca~e straight from Cahforma Superblke School owner and road racing guru Keith Code and it related to what he calls Survival Instinct #7: Locking the front wheel. Unfortunately, I didn't learn these lessons prior to sliding on my back at close to 100 mph toward tum two. Yes, I was wearing a Gardner hel- met, and, yes, I had a little of his Laguna Luck. Yes, I tried to stop a ZX-ll in approximately the same amount of space that I had earlier managed to stop a ZX-7R. Yes, I locked the front wheel. And, yes, I crashed. It was all part of Kawasaki's recent two-day, race track/street ride test of the four 1993 Kawasaki Ninja sportbikes - the ZX-6, ZX-7, ZX-7R and ZX-l1. Though none of the four 'are allnew models, all feature many changes over last year's offerings. L 20 ZX-6 With its Ninja 600 lacking in several key areas, Kawasaki's reputation in the 600cc Supersport ranks has become a tad tarnished. For the most part, the Ninja 600 has become a nonfactor in 600cc racing across the country, with Honda's CBR600 F2 and Suzuki's GSXR600 leading the way at Any Track USA. The folks at horsepower central are hoping the 1993 ZX600 El changes this reputation, and puts them back on the map as a for~e in the 600cc class. Thus, the bIg changes for 1993 come to the 600. In order to accomplish this, Kawasaki engineers had to basically re-invent the ZX-6. . Job number one was to increase the horsepower output of the little 600. Part of this has been accomplished by improving volumetric efficiency via what they call Twin Ram Air Induction. The new system sees cool air enter two scoops in- the front of the fairing; it then travels through the frame tubes on each side before finally arriving in the airbox, thus packing more air and fuel into the combustion chamber and increasing both torque and horsepower while also improving intake efficiency. Everything else in the 599cc, liquidcooled in-line four seems to have been lightened, beginning with the valve train. The 16 valves (four per cylinder) now feature narrower stems (down to 4mm on the E model from 4.5mm on last year's 0 model) that are also lighter (18.2 grams on intake and 16.3 .grams on exhaust as compared to 21.4/20.3 grams on last year's 600). The valves also feature flat tops as opposed to the concave tops of y~ars past. In addition, the tappet weIght has dropped from 16.8 grams to 10 grams. All combined, the lighter valve train allows Kawasaki to use softer valve springs, giving the 600 lower frictional and mechanical losses. The pistons have- also changed. They are also now lighter (down to 123 grams from 142 grams) with a shorter skirt (43.1mm as compared to 47mm on the 0 model); the pistons pins are now 1.4mm smaller, down to 45.1 from 46.5mm while also dropping in weight from 38 to 35 grams. Likewise, the cylinder liners have been shortened. To go along with the lighter pistons, connecting rod weight has also decreased with a smaller diameter big end; the rod weight has dropped 50 grams, dowri to 240 and the diameter of the big end is now 30mm instead of