2006 Kawasaki ZX-10R at Autopolis, Nippon

In the late eighties a group of investors, flush with capital from the engorged Japanese real estate market, decided to build a race track near Kumamoto Nippon. They reportedly spent the Yennish equivalent of $300 million dollars to purchase property and construct what could only be described as a magnificent race track. When it was completed in 1990 it had glass VIP buildings, 48 garages, world class run off, challenging layout, on sight hotel and massive grandstands.

And then the Japanese economic bubble burst. And the money dried up. And the on sight hotel was never staffed. And the world championship races were never held. And the fences began to rust, grass grew up in the seams in the parking lots and the track was, for all intents and purposes, abandoned.

Last year, Kawasaki bought the property for $10 million. Approximately 3% of its original value. Keep that in mind when some real estate agent tells you that a 750 square foot condo for $500,000 can only appreciate in value.

The rusting grandstands watch over turn one while the never used luxury hotel slowly decomposes in
the background.

Kawasaki flew a group of us to Japan to test their new ZX-10R and to try out their new track. A trip to Japan, in the most ordinary of circumstance, is a surreal experience. A trip to Japan to an abandoned world class race track on the top of a mountain to ride one of the world’s fastest production motorcycles borders on delusional.

The journalist in me kept wanting to ask questions like: Who were the original investors? Why are the patio door all open in the hotel that never opened? Was the track used at all for the last fifteen year? Can I have my birthday party here? But the racer in me cared not a bit for the myriad of cosmetic blems on the improvements for which the Kawasaki representatives apologized. I didn’t care about the peeling paint on the corner worker booths or the stains on the concrete walls (all of which are in the process of being rectified) because the course layout is one of the best you will never get to ride.

It’s a big track with twenty numbered turns, a 3000 foot straight away and elevation changes which almost rival Barber. It is so big that a fast lap is still over two minutes. And when wheeling a potent liter bike in a fast right left transition the peeling paint on the pedestrian bridge seems pretty damn irrelevant.

If the global economy requires that I top 160 on a straight paved with the broken dreams of destitute investors, so be it.

In 2003 the global economy required that I be in Homestead Florida to ride a the 2004 ZX-10R. Kawasaki, long mislead by the notion that consumers of sport bikes wanted something that could be ridden on the “street”, was finally getting with the race replica program. No more rubber coated footpegs and comfortable rangy ergonomics, the 2004 ZX was designed to do well in magazine track based comparison tests. It was the rawest sport bike Kawasaki had produced and had many radical ideas like the over engine frame, the alternator spinning at twice engine speed, the slipper clutch and the radial brakes. The bike was a beast. It was fast but it was also a bit of a handful. The bikes we rode had a pre-production transmission glitch which prevented smooth shifting and the power delivery and agile, but nervous, tended to encourage a tight grip on the bars. I ended the day very tired and sore from holding on.

The typical Japanese production cycle for sport bikes is a new model every four years and a model freshen up at two years. The competitive juices must be flowing in Japan because this two year freshen up required some expensive retooling for some relatively minor refinements. Kawasaki has been very responsive to hard core sportbike aficionados and has created a bike that is designed from the ground up to win magazine comparisons and races. Their own test riders have averaged about two seconds a lap faster on the new bike than on last year’s model.

The bike has a redesigned engine which, although similar to the ’04 model is fundamentally all new because it has new cases as well as many internal changes to smooth out the power delivery. The chassis is a refined versions of the ’04 but required a new frame, new swingarm and new forks. The bodywork is new. The exhaust pipe is new. Nothing is a radical departure from the 2004 but it almost an entirely new motorcycle.

The good news is the new bike is easier to ride, handles better, has better low end and midrange power, the same top end and a higher top speed from better aerodynamics. The bad news is the bike has gained eleven pounds. The post script to the bad news is that most of that weight gain is from the stainless steel portion of the exhaust system that contains the catalytic converters which racers and most performance street riders are going to toss within the first week of ownership. Even in stock trim the extra weight is not very noticeable because it is located so low and central in the bike’s chassis.

Catalytic converters revealed.

Autopolis is a big track but the ZX-10 makes such short work of the chutes and straights that it ends up being a pretty hectic two minutes. The track has at least three double apex turns to really test the front end and it has a large number of really slow hairpins including one that actually crests a steep hill at its apex. If the global economy is going to require me to accelerate a 175 horse motorbike on a 55 degree day out of a second gear turn while cresting a hill I want the throttle response to be absolutely predictable.

Empty glass buildings on the front straight at Autopolis.

Now, once upon a time I went to a press launch for a liter class bike. At this press launch the bike had a pronounced tendency to jerk and kick when picking up the throttle from neutral to positive. When asked to share my thoughts on the bike by some of the OEM reps I mentioned, amongst other items, the poor throttle response at low openings. They insisted that it was because the bike was just so powerful that I could not control the throttle well enough and there was nothing that could be improved on the fuel injection.

Gentlemen, there is really nothing that can be improved on this fuel injection. This bike is sporting at least 20% more horsepower than that other bike and this one can be fed throttle precisely and predictably. One can go off throttle at the first of a double apex and scrub the front tire deep into the curve, then breath the throttle open to take the weight back off the front and then drive hard out of the turn. This can be done with absolute confidence that such fine throttle motions will not upset the chassis at all.

Of course, liter bikes are not really about nancying around with partial throttle and double apexes. It is about getting that mount straight up and down and winding the throttle to the stop and watching the peripheral vision blur into hyperspace. This ZX does not disappoint in that regard either. Immediately following the cresting second gear turn that demanded such a fine and delicate touch is a nice long steep downhill chute.

Getting into the power DOWN the hill the front end would get light. Catching third across a seam in the pavement would send the front wheel skyward. Not so much that it requires backing out but enough to get attention. And this is accelerating DOWN a hill.

Setting the front wheel back down while englishing the bike to track left meant sometime that the front wheel was not pointed exactly straight when it became reacquainted with the tarmac. On some of the other 1000s this always led to a tense moment where, on occasion, said bikes have tried to violently throw me off the seat so I can be trampled by a pursuing horde of journalists. The ’06 ZX would give a one fish wiggle then straighten out and get on with the business of rushing up to the brake markers for the next double apex decreasing radius turn.

Rushing up to the brake markers revels my usual peeve. The brakes, which would be fine on the street, are not really powerful enough. That is not to say that the bike cannot be hauled down from speed with a healthy squeeze on the lever but using a great deal of finger strength on the lever is not the way to finely modulate ones inputs. Bikes that have very powerful brakes allow the rider to be more sensitive with the braking input and, therefore, encouraging trail braking antics. My guess is that more aggressive brake pads would help a lot but at a Daytona, a Summit Point or a VIR the diminutive 300mm brake rotors might starting getting awfully hot.

I was trying to carry speed into the first part of this next fast turn and then downshift before the exit of the second apex. The slipper clutch was so predictable and transparent that it was simply a matter of tapping the lever for the downshift, even when I was still hanging off the other side of the bike. No chatter, no dragging, no drama.

Cam and tooth of the slipper clutch. Simple, elegant, effective.

The exit of the second half of this turn always seemed to push the bike a little wide. Now, granted, it could have been my tendency to turn a little early but I think raising the rear ride height would have allowed the bike to finish turns a little more confidently. Since the track had not been used much for fifteen years the pavement was in excellent condition but settling in the track surface had created some undulations and seams. The ZX was pretty settled across all of the track imperfections even when carrying a lot of lean angle at high speeds. The ergonomics are perfect for the race track. The ZX is narrow and allows for easy repositioning. For my 5’10” frame the distance from the clip-ons to the footpegs was just about right so that I could be comfortable on the track without my knees and elbows getting tangled up. This bike is so natural on the track that if you buy one you should be obligated to at least take it to a track day once.

All praise the simple to flip shift linkage and boot friendly heel guards.

The bike is very fast and very powerful but it is much more refined and easier to rider than its predecessor so after a day and a half of riding, instead of being beat up and sore, I was ready for more. The sum of a lot of small changes have added up to a much improved motorcycle.


Everyone loves a cut away.

The ’06 10 has a myriad of technical changes to make a bike that is faster around a track while being easier to ride. Specifically Kawasaki focused on improving the handling of the bike, making the engine’s prodigious power more manageable and improving the aerodynamics. Non-intuitively, some of the changes to the engine are actually to improve the handling.

The new engine sees the cylinders tilted 15% forward (from 20 degrees to 23) and the crankshaft has been raised in the cases slightly to raise the center of gravity slightly. A higher center of gravity will make a bike more inclined to roll into a turn and to hold a line with less force.

One of the biggest changes to the motor is that the double speed alternator has been removed from the engine and is replaces with a conventional alternator at the end of the crankshaft. The double speed alternator appeared on the ’04 and, although small, spun at twice the speed of the crankshaft. This was suspected by many racer to create handling problems by having a very powerful gyro located in the middle of the chassis. Said racers will be relieved at the new placement of the alternator.

Although the ’04 had very competitive power it had a little bit of a lumpy power band lower in the rev range. The ’06 has a great amount of attention paid to smoothing out the power while drastically lowering the emissions of the bike. The fuel injectors are new “ultra-fine” atomizing injectors which emits 50 micron fuel droplets instead of 70 micron. The 10 still has throttle body injectors (one per cylinder) and, although the throttle bodies themselves have been reworked they remain at 43mm.

Ultra fine injectors feed newly designed throttle bodies to reduce emissions and improve throttle response.

On the intake side of those throttle bodies is a new ram air duct and a new airbox and on the downstream side the ’06 gets new intake tract porting and smaller intake valves (31mm vs 30mm). In theory the smaller valve should improve low end power at the expense of high end power but in this case Kawasaki was able to improve the low end without any hit to the top end power figure.

New intake track, smaller intake valves. No one at the track seemed to know for sure but it appears that
Kawasaki has fitted the bike with adjustable cam sprockets if you want to play with your cam timing. Also
note the steel intake valve, titanium exhaust valves and trick oval wire valve springs.

The ram air is fed straight into the frame. The airbox picks it up from inside the frame rails.
This is a very clean design.

The exhaust gases flow out into an all titanium pipe which feeds two catalytic converters under the engine (which also isolates the hottest part of the exhaust away from the rider). The pipes then join together and curve up by the rider’s calf where an ECU exhaust butterfly valve is located. The pipe then splits to feed the two underseat mufflers.

Cooling the engine is a new lightweight Denso radiator.

Grandma, what a big air intake you have. 

The results of these efforts where to produce an engine with perfectly linear throttle response particularly in the first half of the rev range and maintain the peak horsepower while meeting all global emissions laws.

The chassis remains the frame over engine layout which makes for a very compact narrow motorcycle. However, in ’06 Kawasaki addressed a few of the handling complaints about the ’04. The steering head has been moved forward slightly and the rake has been increased slightly to move a the weight bias slightly rearward. Also to improve rear grip the ’06 has a lowered swingarm pivot. The swingarm itself is slightly shorter but takes its styling cues straight from the MotoGP paddock with massive under slung bracing. A very visible Ohlins steering damper is installed across the top triple tree to take out the shakes when the front wheel is set down slightly off center.

Massive underslung braced swingarm gives the chain adjuster blocks a bit of an inferiority complex. 

A motorcycles suspension works best when a bike is straight up and down but track designers keep bikes leaned over on their sides. Engineers have to solve problems of how to get a motorcycles suspension to function while banked over in a turn. Kawasaki paid attention to this conundrum by specifying the trendy black diamond like coating on the front fork sliders to reduce stiction under side load and by tuning in some lateral flex in the swingarm.

Diamond-like coating is forever.

American energy policy not withstanding, it is much easier to conserve energy than produce it. Kawasaki slickened up the ZX-10 with a all new fairing (incorporating new headlights and slick integrated turn signals). These changes are claimed to be the equivalent of an additional 10 bhp at high speeds.

To convert all that potential energy into waste heat the ZX-10 retains the 300mm petal front rotors with radial mounted Tokico calipers of the “4 piston, 4 brake pad” variety. The improvement for ’06 is a radial master cylinder.

For whatever reason Kawasaki seems resolute not to keep the instruments simple so this year they have a tach with a configurable amount of contrast but in its default position (I’m a busy guy, I don’t have time to adjust my tach constrast on the way to work in the morning) it was barely readable. The instrument cluster does incorporate a lap timer and a clock.

In the USA we get green, black or orange. We don’t get the refined Euro only silver one. For the record, I love the solid color paint schemes. Classy.

Not the prettiest back end but it will do.




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