Then & Now: Kawasaki Z1000 vs. Z1

Rising sun superbikes

During its development, the 1973 Kawasaki Z1 was codenamed New York Steak. And it was just that: 23 percent larger than Honda's benchmark 750cc Four, it busted open the fledgling superbike ranks and would soon make its impact in racing, too. Blasphemously heavy at 542 lbs. wet, the Z1 did everything to excess, from its audacious 903cc DOHC four-cylinder engine to its roomy cockpit, enormous linkless chain with proprietary oil pump, and quartet of chrome-plated megaphones.

In '73 few street machines could beat it, and in '77 Reg Pridmore took the AMA Superbike Championship for the second straight time aboard a Pierre des Roches-tuned Z1. "Its forte was power, but it was making 141 bhp in a 100-bhp frame," Pridmore explains. "Pierre worked hard to get the geometry right and the flex down. We caught some of it, but when ridden hard it would still give you a hard time. At some point it would just do whatever it wanted, but it's the racer's attitude to just deal with it."

Mike Vaughan worked in Kawasaki marketing during the Z1's heyday and squirreled away this low-mileage example. Now as then, the Z1 is bigger than life, from its huge engine to the broad spread of the gas tank and longhorn bars. Thumb the starter and the engine immediately utters a warning growl.

First gear engages with a loud clack! The characteristic Z1 primary-gear whine grows shrill as you feed in throttle, and the four cylinders pull like a team of Belgian draft horses to yank the bike off the line. Onto the Horse Thief Mile we go, engine buzzing and surging, carburetors gulping air, transmission clacking from gear to gear.

In its day, the Z1 was credited with a 12.4-second quarter mile at 111 mph- smoking fast for the time. But on the road course and again on our road loop later in the day, the Z1 fails to particularly impress. Like the other bikes it makes solid midrange torque, and it's also revvier than most of the other engines, yet on the track all of its weight comes to visit, and I felt high and not so mighty on this big beast.

Instead of a track master, the Z1 is instead a master of the open road. Sitting proud and latching onto the tall handlebar, the 160-mph speedometer and 12,000-rpm tach urging me on, I could see the California horizon practically fading into Nevada and then Colorado, over the Rockies and straight for the East Coast. It's that good of a touring mount, and no wonder many Z1s ultimately sprouted windshields and saddlebags. Right out of the crate, the Z1 was a great multi-purpose bike and a commanding street ride; on the track it needed to shed poundage and grow a racer's powerband.

On our "Then & Now" day in the sun, there wasn't a bigger contradiction than between the Z1 and its great-grandchild, the new 2010 Z1000. Kawasaki turned the engineering train fully onto the streetfighter tracks with the Z1000, producing an aggressive, ass-up-and-nose-down hooligan. Its quick-revving 1043cc four is worlds apart in character from the old Z1, and its appearance is out of another time-space continuum as well. In a word, the new Z1000 is a superbike without the bodywork. With a tiny instrument panel, steep fork angle and frenetically revving engine, you almost feel like you're due for a nosebleed when riding it. That is, until you enter the powerband and get thrust into the next time zone, sprinting down the quarter in under 10.6 seconds at a sizzling 131 mph.

Kawasaki went all-out in designing the new Z1000, and rather than modify the existing ZX-10R engine, the company conjured up a new mill. The new Z1000 makes 123 bhp to the Z1's 64, and not only does it love to rev, it has to rev. With maximum useful power not available until the far side of 10,000 rpm, it needs a rider that really wants to turn the throttle. Unlike the other new bikes in our group, this means you'll be blurring through the gears at every stoplight and freeway on-ramp-and while that's great for a track day or street-racing your buddy, it's a big demerit for everyday riding.

The Z1000's four-piston front brakes are stupendous, even compared to the big optional double discs on the original Z1. But so focused is the Z1000 on quickness and responsiveness, that on the Horse Thief Mile, where the Z1 was linear and stable, the front wheel felt ready to tuck under-a disquieting trait at best. Not every sensational hotrod feature is desirable.

Call this one a split decision.

Price new $1895 $10,499
Dry weight 506 lbs. 459 lbs.
Horsepower 64.2 bhp @ 8500 rpm 123.2 bhp @ 10,000 rpm
1/4-mile 12.4 sec. @ 110.7 mph 10.55 sec. @ 130.7 mph
Tire size 3.25-19 front, 4.00-18 rear 120/70-17 front, 190/50-17 rear
Brakes Dual discs front, drum rear Triple discs
Wheelbase 59.0 in. 56.7 in.

The Kawi is the horsepower king of this comparo, putting 123.2 bhp to the ground at 10,000 rpm like only a big-bore inline-four can. That torque curve isn't too shabby either. It all adds up to a bike that feels downright ferocious when you twist the loud handle.

The Z1000 strikes a balance between the sporty riding position of a ZX-10R and the upright comfort of a Concours14, though engine vibration is omnipresent in the seat and bars. You feel every one of the big Z's pounds at slow speeds, but it seems to get lighter underway.

Kawasaki Z1000 | Price $10,499

Tech Spec
Engine type: l-c inline four Frame: Aluminum twin-spar Rake/trail: 24.5º/4.1 in.
Valve train: DOHC, 16v Front suspension: 41mm Showa fork with adjustable spring preload, compression and rebound damping Seat height: 32.1 in.
**Displacement: **1043cc **Rear suspension: **Showa shock with adjustable spring preload and rebound damping Wheelbase: 56.7 in.
**Bore x stroke: **77.3 x 56.0mm Front brake: Dual Tokico four-piston calipers, 300mm discs Fuel capacity: 4.0 gal.
Compression: 11.8:1 Rear brake: Tokico single-piston caliper, 250mm disc Weight (tank full/empty): 488/459 lbs.
Fuel system: EFI Front tire: 120/70ZR-17 Dunlop D210F Colors: Orange/white, black
**Clutch: **Wet, multi-plate Rear tire: 190/50ZR-17 Dunlop D210 Availability: Now
**Transmission: **5-speed Warranty: 12 mo., unlimited mi.
**Measured horsepower: **123.2 bhp @ 10,000 rpm
Measured torque: 73.6 lb.-ft. @ 7500 rpm
Corrected 1/4-mile: 10.55 sec. @ 130.7 mph
**Top-gear roll-on: **2.45 sec.
**Fuel mileage (high/low/avg.): **36/31/34 mpg
Then & Now: Kawasaki Z1000 VS. Z1
The Z1000's designers must have loved the Jedi Starfighters in Star Wars. Racy styling is galaxies apart from the original Z1's classic design-and makes no apology for it either.
The futuristic look continues with the LCD instrumentation. Watch the bar-graph tach closely, because the Z1000 loves to rev-actually, it needs to rev to make useful go-power
With its one-year-only orange-and-root-beer paint scheme, the '73 Z1 can never be confused with any other machine. This was-and still is-a big motorcycle.
No brag, just fact: DOHC inline-four's 9000-rpm redline was stratospheric for any street engine back in the day. Race tuners would soon nearly double the Z1's as-delivered horsepower.