Kawasaki KZ650B/reviews
Motorcycle Mechanics 1977
A little more than a year ago when the Z650 was first announced it was greeted as one of the best bikes Kawasaki — or Japan — had produced.
It wasn't quite as quick as the 900 and 1000cc fours but it was lighter and generally easier to handle. Only the 550 Honda had the same elusive nurture of performance and rideability, in the same price range, and the 650 was the more powerful. So it was nice to find that the 650's attributes weren't merely rose-tinted memories; the reality was as comfortable and sure-footed as ever.
Probably the first and most lasting impressions of the Kawasaki are of its comfort and the relaxing way in which the handling blends with the willing motor. It goes easily and it goes fast. It also has quite an amazing spread of power, on the dyno we wound it down to 1700 rpm pulling full throttle. From there it pulled on up to its peak and carried on to 9600 rpm and the power still didn't fall off.
The torque peaks at 7000 rpm, the power peaks at 8000 and then stays up there giving almost the same horsepower right through to 9500. And the motor, a conventional DOHC four, with a shell bearing crank, is unofficially claimed to be reliable to well over 10,000 rpm. This much is borne out by the long distance records set by American Kawasaki 650s.
The wide spread of torque makes the choice of gears less critical but the five-speed box nevertheless gets the most possible from the engine's output. As the load tails off in each gear an upward shift takes you right on to the peak load in the next gear.
Rapid performance and a smooth pick-up, particularly when switching from overrun to power, make the engine unit as impressive on the road as it was in the test house. And when you need to be careful on wet and greasy roads the same characteristics make the Z650 easy to handle.
As soon as you sit on the Kawasaki it feels comfortable, a bit big and heavy perhaps but there is a reassuring firmness to it which stays with the bike once it is moving. Starting is more awkward than it need be because the starter has a lock-out switch operated by the clutch, and the clutch needs to be pulled in before the starter will turn, even when the gearbox is in neutral. As there is existing wiring to light up the green neutral light it ought to be easy to isolate the lockout switch when the machine is out of gear. Our model's cold-starting was a bit hit-or-miss. Sometimes it would fire up straight away, sometimes it needed several short bursts on the starter. Then it needed quite a long warm-up period before the motor would respond normally.
After our 24-hour test of the 650 last year, and despite the foul weather conditions, we could find very little wrong with the bike. We thought maybe this only related to highspeed track performance but the Kawasaki is just as sweet under normal road conditions. There were three or four complaints, the worst of which was clutch judder when pulling away quickly — this got worse during the test until it prevented rapid take-offs altogether. The front disc brake failed at low speed — below 30 mph — during heavy rain; it was OK above this speed or if the brake was used frequently enough to keep it hot. In the dry the brake was good, with plenty of feel to the control although it didn't seem as powerful as the optional double-disc. In all conditions the rear drum brake was sensitive with just enough power to make it usable without locking up too easily.
A lot of the controllability of the Kawasaki comes from its good riding position, particularly the seat-to-footrest relationship. This lets the rider take as much force as he wants through the footrests, making control under acceleration or over sudden bumps, a lot easier. And even if you're taking all your weight through the footrests it's still easy to operate both control pedals.
The suspension gives a comfortable ride but this has always been a weak point with big Kawasaki’s and the 650 still has its problems. The front forks with some 5.5 inches of movement do a pretty good job, smoothing out the bumps without any pitching and even coping with heavy braking over bumpy surfaces.
The rear suspension with roughly the same spring rate as the front, only has about three inches of movement but the dampers just don't have enough control over the springs. Deep into long fast turns the Kawasaki would start to wallow, and bumps in a corner would set up a weave as the rear end started to move about.
In normal road conditions this weaving was barely noticeable though, and generally the handling was good with more than enough feel to cope with wet roads.
In fact the overall character of the bike makes it very easy to forgive the few faults it does show. The motor is amply powerful but flexible, giving exciting acceleration at the top end without losing the ability to potter slowly and silently at the other. The handling, ride and braking are about as good as you can get anywhere else; as a sports bike it is fun, as a tourer it is more than capable and even as a heavy traffic commuter it is still easy to handle. Economy is not a particularly strong point. If you use the performance the fuel consumption drops into the mid-30s, but a typical crosscountry run will give maybe 50 mpg and a range of about 160 miles before needing the tank's reserve.
The four-cylinder motor, with its four-into-two exhausts follows conventional practice. Power is taken off the centre of the crankshaft through a HyVo chain to an idler shaft which drives the clutch. Normally smooth in power delivery and in general running, the 650 had a patch of tingling vibration between 5000 and 6000 rpm, which is, unfortunately the speed at which the engine spends most of its time.
With some 50 bhp getting to the back wheel, road performance is about as rapid as you want to make it. The gearing, shown by our graphs, gives an ample reserve of power up to 100 mph and more. With a practical top speed of around 115 mph, detail design is on the good although the Kawasaki is let down by underpowered lighting with its standard headlamp. The alternator is the type first used 400 twin and makes a compromise the simplicity of the permanent type and the controllable power of a field coil. A field coil is mounted inside a cast rotor carried on the lot the crankshaft.
Kawasaki Z650 Performance & specification
Track Conditions: Wet, no wind. All engine tests run on a Heenan Froude DPX3 chassis dynamometer fay Lines Engine Development, School Lane, Baston, Lines.
- max speed....................................... 116 mph
- 1/4-mile.................. 13.9 sec at 101 mph
- braking from 30 mph.............................. 27ft
- fuel consumption; average over test.......................... 50 mpg
- speedo error........... 5 mph fast at 70 mph
- ENGINE: DOHC in-line four, wet sump, four Mikuni VM24SS carburettors, twin coil and cb ignition, 12V lighting from alternator and lOa-h battery.
- displacement.................................... 652 cem
- bore x stroke............................... (2x54 mm
- compression ratio.................................. 9.5: t
- claimed output............ 64 hp at 8500 rpm
- Transmission*inverted-tooth chain and spur primary drive, multipiate clutch, five speed gearbox, final drive by chain.
- Chassis: telescopic front fork with 5.5 inch stroke, rear swing arm, five pre-load position dampers, 3.15 in. stroke. Hydraulic disc brake front, sis drum brake rear.
- front tyre........................................... 3.25H 19
- rear tyre............................................ 4.00H 18
- wheelbase............................................. 55.9 in
- castor..................................................... 63 deg
- trail........................................................ 4.25 in
- overall length.................................... .87.4 in
- overall width...................................... 33.5 in
- dry weight............................................. 465 tb
- test weight............................................. 488 Ib - fuel tank................................................ 3.7 gal - oil tank................................................ .6 pints