When all around were developing large capacity sports machines, Kawasaki had a different take on the job. The Z650 proved a popular and cheap way to get a high performing motorcycle, it also spawned the air-cooled middleweights of the change over between the 70s and 80s, which in turn led to the dawn of the truly modern motorcycle in the form of the GPz600.
The Z650 is every bit a scaled down version of the successful Z1 design and, as such, it shares much of the looks and a good deal of the performance too. Often played down in the family tree, nestling in the shade of the larger machines, the Z650 is arguably a pivotal moment in Kawasaki’s success. The design was a great achievement in its own right, stealing sales off the Z1, as well as spawning the Z500, 550, and 750, and then the GPz series of the 80s, a real legacy indeed.
Back in 1976 there was a vast selection of middleweight machines vying for the customers cash, from the RD400 all the way through CB400’s, GT380/550’s and GS550’s sat in showrooms luring the buyer in. This would indicate one of the main reasons behind the 650cc choice that Kawasaki made, as the Z650 would stand out from the norm. Hopefully ensuring that a buyer would stretch just that little bit further to buy the biggest machine they could afford as well as catching a few not able, or wishing, to buy a full on 750 or 1000. Reduction in manufacturing costs meant the Z650 was more than a few quid cheaper than machines only a few CC’s larger. The initial batch of B1’s sold incredibly well, outstripping other machines of the time by a good margin.
Despite sharing it’s designer and overall looks with the Z1, the 650 engine is very different beast once the covers and casings are removed. Unlike the Z1, with engine components that ran in roller bearings, the crankshaft of the smaller engine spins in plain metal bearings and requires high oil feed pressure to maintain their operation. This was a far cheaper way of assembling an engine, saving much weight in the process, and has since become the industry norm. The large, one-piece crank transmits its power via a hefty Hy-Vo chain, on to a jackshaft and vibration dampers, before entering the five-speed gearbox, the result being a quieter and smoother engine than larger capacity Z series. The valve shims, securely held in place by buckets, were placed in pockets underneath the twin cam shafts, preventing any movement at high engine revs. Damping out any other vibes is a large alternator sat on the left hand end of the crankshaft, even so, the Z650 is a free revving beast and, as seen in subsequent developments, capable of power outputs far in excess of the original 60 plus horses.
These days finding a good clean example is a relatively simple task and prices are still reasonable, this is in contrasts to the cost of owning, buying or restoring a Z1, particularly an early version.
Punching well above its weight
The Z650 is much larger in the flesh than one would imagine. No matter what you have read elsewhere about it being a small machine with the heart of a superbike, make no mistake this is a big bike. It does display a cheeky stance though, with a low seat, sweeping silencers and those streamliner clock housings raked back, quite steeply towards the rider. These pointers suggest a relatively sporty and exciting ride well before you actually get on it, and little disappoints once on the move.
Thankfully, the Kawasaki chassis boys, having learned much from their previous, more flimsy designs, carried out much work to get the Z650 to handle like a modern machine should. Although similar in design to the Z1 chassis, the tubing, with the exception of the swing arm, is generally much larger in diameter and consequently far stronger. The Z1 had considerably more engine than the chassis could handle whereas the new 650 was far more balanced and harmonious. There is heavier gusseting around the welds and the engine is held in place with heftier mounts too, this adds up to a real powerhouse of a frame that is only let down by the bouncy bits hanging off each end.
Once loaded, the standard suspension set up is fine but can be upset easily, the 650 immediately loses its petite and agile tag, reverting to being a big bike simply playing at being a small one. This isn’t a major problem and somewhat typical of most bikes from the period, the key to riding the Z650 fast is choose your line, and stick to it as closely as possible. Of course replacing the rear shocks, the major culprit in these proceedings, improves things immeasurably; the Japanese were some time perfecting suspension components, especially rear units, and, as the original items often never made it to the first MOT test, it would be hard to find a machine in use today with these still in place.
For the weight of the machine, the single front brake can sometimes get a little overwhelmed particularly with repeated heavy braking sessions. It does work well, with a good progressive feel but, it is a close run thing at times and you can be left wishing that, whatever it is you are braking hard to avoid could be just that little bit further away. Thankfully Kawasaki chose to supply this machine with a right fork leg equipped to take a second caliper and the wheel an extra disc and a handy mod is to add a second stopper.
The Z650 was popular and plentiful during the time of its reign, and few escaped without the odd mod or two, making finding an original example quite difficult. The good thing is these mods are often achieved without resorting to anything more drastic that bolting parts on to existing mounts so reverting back to how Kawasaki first intended it to be shouldn’t prove difficult.
Kawasaki Z650 Model history
The Kawasaki tale is one of motorcycling’s great success stories. They appeared, as if from nowhere in 1962, and within a ten-year period had reached the very top, producing class leading motorcycles that turned the two-wheeled world on its head. Following the success of the Z1, the time was right to back that up with an equally impressive middleweight machine. Ben Inamura, the designer of that Superbike, was single-handedly given the task of creating the new machine and in typical style he chose a capacity long since lost.
The real reasons for this switch from the obvious 750cc category may never be known, but several ideas can be thrown around to make sense of it. Back in 1968, Kawasaki had a 750cc bike already nearing production when Honda announced the CB750, thus prompting Kawasaki’s return to the workshop and the subsequent Z1’s birth. Suzuki had been developing the GS750, albeit a straight take off of the Kawasaki twin overhead camshaft, roller bearing crank, design. These may have been the catalysts that prompted the new Kwak to be a smaller engine size than the rest but one thing is for certain, by the mid 80’s the middleweight class had become the centre of attention for all manufacturers.
A 650cc machine was, like its 900cc big brother; different enough to grab attention, stylish and fast. It was the first Japanese machine to have a formal press launch, something we take for granted in modern times, and the worlds journos sampled the new Kwak at Ingliston Race circuit, on the outskirts of Edinburgh. This proved to be a good venue and the tight track demonstrated the Z650 and highlighted its many attributes The chassis was more than capable of keeping the 64 bhp (the equivalent of 98bhp per litre, the highest for any machine over 500cc at the time of the Z650 launch) in check, enabling high corner speeds to be attained. The lightweight of the design coupled with an impressive 41 ft-lbs of torque enabled it to blast up the quarter mile in around 14 seconds, less than a second adrift of its larger capacity sibling. With over 120mph on tap, the top speed was little down on the bigger bikes of the period making the Z650 a genuine alternative to a bike 750cc or above.
Kawasaki Z650 Timeline
Frame number: KZ650B-000001 onwards
Single disc mounted on the front of the fork leg spoke wheels
Colours were candy red and emerald green
Frame number: KZ650B-027501 onwards
Caliper now on the rear of the fork leg and a new charging system was introduced. New colours of dark blue and red were not popular.
Frame number: KZ650C-010001 onwards
Twin discs up front, plus a disc on the rear, and alloy wheels make this model instantly recognisable and very popular.
Available in the UK in one colour only stardust silver.
Frame number: KZ650B-046201 onwards
The reintroduction of the original colours used for the B1 saw a return to popularity for the basic Z model. Needle roller bearings fitted to the swing arm pivot in place of plain bushes, not a popular move for those who had to replace them due to the fragility of the bearings.
Frame number: KZ650C-022801
Little changed compared to the C2 model
Frame number: KZ650D-010601 onwards
The custom version of the C3 known as the Z650 SR with high bars and 16-inch rear wheel. Also, at 221kgs, the heaviest of the 650’s.
Frame number: KZ650D-026001 onwards
As per the D2 but different graphics
1980 Z650 E1
Frame number: KZ650E-000001 onwards
This was a US only model sold as the KZ650 LTD with a reduced power, 60bhp engine, single disc up front and a drum rear.
Frame number: KZ650F-000001 onwards
a hybrid of the B and C versions with cast wheels, twin discs but returning to a drum rear stopper.
Frame number: KZ650F-007201 onwards
black engine casings, no kick-start and a transistorised ignition replacing the points.
Frame number: KZ650D-028101 onwards
Custom version of the F model
Frame number: KZ650H-000001 onwards
Once again, a US only model sold as the KZ650 CSR similar to the LTD but now fitted with wire wheels
Frame number: KZ650F-012401 onwards
CV carbs now replace the original mechanical slide models
Front mudguard no longer chrome but painted to match the bodywork.
Frame number: KZ650F-014301 onwards
The very last of the breed with little difference between the previous F3 model. The GPz range finally takes over the mantle established by the Z650.
Kawasaki Z650 B1 Specifications
- Engine – Air cooled 4 stroke DOHC inline four
- Capacity – 652cc
- Bore/stroke – 62mm x 54mm
- Power – 64bhp @ 8500rpm
- Torque – 41 ft-lbs @ 7000rpm
- Carburetion – 4 x Mikuni VM24SS
- Transmission – 5-speed wet clutch chain final drive
- Frame – steel twin loop cradle
- Suspension – 36mm telescopic forks. Twin shock rear
- Brakes – 275 mm disc single piston floating caliper. 180 mm single leading shoe drum
- Wheels – 3.25 x 19, 4.00 x 18
- Weight – 211kgs
- Top speed – 125mph
- Wheelbase – 1420mm
- Fuel capacity – 16.8ltrs
Kawasaki Z650 Gallery