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1998 Kawasaki ZX-6RMSE Ratings

1998 Kawasaki ZX-6RMr. Takashi Hiraga is the man behind the engine design of the new Kawasaki Ninja ZX-6R. His goal was to produce a lighter, more powerful engine and, as always, an environmentally friendly one for the concerned Californians.

AddedDate Added: 8th September 1997
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What he came up with is the typical haul-ass Kawi motor with three more horsepower at the top and no loss in the low or mid-range. This has been achieved by cutting the intake length down 7 mm and redesigning the combustion chamber.

Of course, other refinements had to be made to complement these modifications. The redline is now up to 14,500 from 14,000, and the new combustion chamber was developed directly from the \'96 ZX-7R Superbike. This gives the little Ninja a higher 12.8:1 compression ratio, and it even burns cleaner. Kawasaki was able shave 3.5 kg of weight off of the engine. Magnesium valve and clutch covers are 33% lighter and a reshaped oil pump cover cuts 103 grams off the old style, which in total is a weight savings of 77%.

The head on the ZX-6R (J1) has a new intake valve assembly as well. The tappet surface where it contacts the cam lobe is changed from flat to slightly crowned to improved durability. The retainer\'s collar diameter has also been changed for a more uniform spring pressure on the retainer. Finally, the valve collet\'s groove diameter has been slightly reduced for more accurate mating between the collet and valve. Intake and exhaust cams lost 110 grams and gained new, smaller, lighter cam sprockets.

The cylinder, which is obviously lighter by feel, is made out of a composite-plated all aluminum material and is now linerless. This design cuts 930 grams off the old cylinder even with the additional 5 mm added to the bottom of the skirt to reduce piston slap.

The piston crown is reshaped in order to match the new combustion chamber and to bump up the compression. Crankshaft weight is always important and the new unit is reduced by 890 grams (12.3%). This really makes a difference in spinning up the motor. A smaller flywheel and rotor don\'t hurt either. Now that the motor can spin higher revs, the connecting rods needed to be beefed up to deal with the increased power output. You wouldn\'t want to throw a rod on the bank at Daytona or, as in my case, on the Sulby straight at the Isle of Man.

The housing width of the clutch assembly has been shortened by 5.6 mm, and the pull rod is drilled out for weight reduction. The steel clutch plates are reduced in thickness from 2.3 mm to 1.6 mm, which saves 260 grams, but the surface area is the same. The release shaft has also been turned down for lightness as has been the oil pump drive shaft, saving 86 grams. The oil pump cover is smaller, and fifth gear has been replaced.

Modifications to the water pump include a new mechanical seal and magnesium body. The ignitor box is smaller and Kawasaki now uses what they call stick coils. You know, the coil is in the sparkplug cap. The ignition timing is improved as well by increasing the numbers of triggers on the pulsing rotor. The ram air has been redesigned. In the front of the bike there is a big scoop coming out just under the headlights. Apparently, this moves the two sides closer to the center, allowing for a narrower and flatter duct construction. This reduces flow resistance and increases air pressure by 12% at high speed. A thinner wall design of the air ducts also translated into a 450 gram weight loss.

Finally, the exhaust pipe wall thickness has been increased from 1mm to 1.2 mm at the header to reduce heat-induced expansion. In the muffler section, you will find Kawasaki\'s new KLEEN honeycomb plate-type catalyser. They say it delivers extremely low emissions without loss of power. This means there is no bulky canister hanging off the bike or a million feet of hose routed around for smog crap.

Mr. Nobumasa Taniguch is the designer of the latest ZX-6R chassis. He has worked on the previous ZX-6R F and G models and has a real knack for producing bad-ass looking bikes. His main goal was to improve handling and reduce weight. 1.5 kilos is what he lost in the new design, and it looks bitching.

As far as the handling, fork pitch is increased from 205 mm to 210 mm, and the fork offset is changed from 30 mm to 28 mm, to improve front end feedback. Ball bearings replace the tapered roller bearings in the steering head for a lighter feel. At the rear of the bike, the swingarm is redesigned in a pentagonal box-section tubing with internal bracing.

Shock length, tie-rod length, and suspension arm positions are revised in hopes of better tractability. Both the front and rear have stiffer springs and the damping has been improved. The handlebars are mounted under the triple clamp now, which allows for shorter fork tubes and a little more weight savings. Even the gauges have been slimmed down for weight.

As usual, the first session at the Valencia track where the ZX-6R was introduced, entailed just getting used to the feel of the new ZX-6R. The seating position is comfortable and all the controls proved to be well within my reach. I wanted to change the shift pattern to race style but, since we were sharing the bikes, I didn\'t have it changed. No problem; I go both ways.

Since I was at this track two months earlier, I figured I had the advantage on everyone except Kent Kunitsugu. Don Canet, on the other hand, has never been to the Valencia circuit and I had a bone to pick with him. The last time I rode with him, I crashed and broke my wrist and collarbone. We are both instructors for the DP Safety School but, as always, we were grudge-racing at the end of the day and I high-sided right in front of him. I guess I owed him one. He high-sided in front of me at Daytona in \'93.

After the first session was out of the way, I got down to some serious testing. I asked if we could lower the front or raise the rear to get the weight forward. Upon my return to the track, the 6R felt more planted in the front and it started to respond like a race bike. Each lap, I pressed harder and the 6R responded accordingly. Soon, however, the suspension started to give in. The ZX-6R is fitted with new 6-piston calipers to match the dual semi-floating 300 mm discs up front. I was really happy with how well the new brakes grabbed and maintained their feel. The previous 6R brakes had a good grab at first but then became spongy and lost their bite. The calipers look the same on the outside, but the piston size has been split between two 27 mm and one 24 mm piston on either side, dramatically improving initial action.

With confidence in the brakes and the attitude of the 6R feeling better, all I needed was a little sorting out of the suspension. I added some rebound in the rear, from 12 to four clicks out, and I set the front at five clicks of rebound and three clicks of compression. The front felt better under heavy braking, but it was only temporary, I also had some turn-in problems.

Valencia has a lot of turns and braking points, which is very helpful for finding the pros and cons of a bike. The 6R negotiated the circuit well, but I needed to find a little something else to get it spot on. As the day went on, it warmed up, and the tires started to work better. More ride height added to the rear with some additional preload fixed the turn-in problem and the 6R came alive. Hard on the brakes into turn one, drop a few gears, throw it in, and gas it out; no problem.

After a big feast and a good BS session about the bikes, we were at it again. My first concern was eliminating the front-end chatter that I had found while chasing Canet. More compression was the solution I came up with. After a few easy laps to warm up the tires, I began to gas it to see if my suspension knowledge was up to par. Hard on the brakes into turn one, then down the short straight to turn two. Turn two is a U-turn left-hander so it takes a lot of braking to slow down. I got on the brakes so hard that the rear wheel came off the ground. No worries, the Ninja held its composure. Out of the hairpin, up a few gears, through the kink, and into turns four and five. These are the first two rights with turn five having a deeper apex. The chatter seemed to disappear, and the bike held its line.

Turn seven is a slightly down-hill left with a bumpy entrance. You can make up time here if you don\'t freak out. Up the inside and grab a handful of brakes, pitch it sideways, and push the competition out of the way. On this go round, the front felt fine and I knew I had gone the right way with the added compression. I like this turn because it\'s sort of off-camber and you really get a lot of lean angle; it\'s a good peg dragger.

The long left-hand sweeper of turn twelve is a measure of just how much gas can the bike take without high-siding. It is always a challenge. I tried a few times but was unsuccessful at getting it all right. Fortunately, Canet wasn\'t behind me and the 6R felt fine leaned over on the gas. I just had to watch it sometimes because I would come up on some of the other riders real fast through there. There isn\'t much time to make a change in your line once committed in that section.

I was pleased with the performance of the new Ninja ZX6R (J1) and I believe its engineers were also. On our way back to the hotel, we discussed the finer points of the 6R and what we liked and disliked about the bike. It seemed that everyone enjoyed the new Ninja and I, for one, was very impressed . The riding position is comfortable and all the controls are easy to use. Everything blends together quite well. The power reminded me of a 900 or 1000cc sportbike: lots of mid-range grunt without any loss as redline is approached. Obviously, 600s are only going to make so much power, but I think the 6R is at the head of that class in power.

If the stock configuration doesn\'t suit a rider, Kawasaki has a race kit available that includes everything from cams to a special tach. Iain MacPherson was on hand in the morning and, although I didn\'t get to ride with him, the new World Supersport version of the ZX-6R (J1) looked mighty fast and sounded fabulous. Kawasaki has taken the US race team in-house for 2000 and, with Eric Bostrom at the helm of the new Ninja 6R, they should do very well, maybe even win it.

My conclusion? It hauls ass, handles well, and looks bad-ass as always. And, you can go out today and buy a new Ninja ZX-6R at your local dealer. None of that wait-until-the-factories-have-raced-them-at-Daytona-and-everywhere-else before you can get your hands on one.

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