When the Z1 hit the streets back in 1973 it caused a storm. The market had already been formed by Honda's 750 four but the big 900cc Kawasaki was an altogether flasher and faster device. In fact, the competition between these two companies, and later efforts by Yamaha and Suzuki, led to today's almost miraculous four cylinder rep's. It wasn't a direct route to the current light and immensely powerful fours, the whole Z900/1100 range was blighted by excessive mass right throughout its life. Though fast when they were introduced, these days a good 550 or 600 will see them off. They do offer a better spread of torque and tougher engine, as well as authentic retro style.
The Z1 redefined the concept of engine toughness. True, Honda's CB750 had been relatively free of vibration, oil tight and generally strong, but it was burdened with such antiquities as a separate oil tank and hyvoid chain primary drive, the latter not helping the gearchange action. In contrast, the Z1's basic engine layout has been carried forward, with the addition of watercooling and sixteen valves, into the modern era. The only possible weak area's the clutch, which the more inconsiderate owner can burn out when indulging in massive wheelies.
High mileage, as in over 75000 miles, may take out the eight valves, especially if they haven't often been checked. Camchains last 50,000 miles, or more, if given the odd tweak on the tensioner. Valve guides can also wear out. Engines that have been used in proddie racing can take out their crank, but that takes an awful amount of abuse, but worth thinking about if the mileage's suspiciously low and vibration levels seem high.
Sources of poor running can come from dying coils (sometimes parts from later models are fitted and don't work properly), the advance/retard mechanism wearing badly, ancient spark plugs (they are easy to get at but old engines can strip their threads), and rotted out silencers on the standard four into four or mismatched jetting on the aftermarket four into one's - most bikes quickly rotted their standard exhaust system.
The Z1 had a well built gearbox with a slicker change than similar era Honda's, helped along by the gear primary drive. After 60,000 miles - or somewhat less if regular oil changes have been neglected - missed changes can occur due to worn selectors, and this is one of the few easy ways of judging the real mileage of these engines. Also try a few examples to get used to the level of secondary vibration - there's so much mass to absorb it that there isn't that much of a buzz on good examples.
The engine makes around 80 horses when in fine fettle, with the strong power above 5000rpm, though it'll run at much lower revs without any of the transmission jerkiness of the CB750. Any transmission lash coming from a worn drive chain or sprockets, the former often lasting for less than 5000 miles.
Whilst 80 horses was pushing the boundaries of engineering in the early seventies, and the poor old Brit bike industry didn't know what the hell had hit it, Kawasaki showed no inspiration in their chassis design. Weighing in at around 500lbs, the only good point about the chassis was that its hefty tubular steel frame was resistant to mild shunts; it would bend rather than break, but only when the forces involved in a collision were such that the rider was liable to be maimed or killed.
The fat old dame had barely adequate suspension and brakes. Twin discs out front were desperately needed and fitted to later models; also available as an optional upgrade. Not that the stock discs were in any way brilliant, suffering from the usual wet weather lag and lack of feedback. Age did nothing to transform their operation. Given that the front forks were on the wimpy side, a much favoured option's to fit a more modern front end - almost anything's better than the stock stuff. Such mods, as long as they are well done and not trying to disguise crash damage (which can only really be checked by whipping the petrol tank off to clock the top frame rail) shouldn't affect the value of the bike.
Similarly, the back end's on the soft side with a weak swinging arm. An alloy swinging arm, preferably with eccentric chain adjusters, and set of Koni or Hagon shocks, goes a long way to damping out the high speed weaves. There's nothing much that can be done to alleviate the occasional violent speed wobble - that's mostly down to the weight distribution and the steering geometry, though it's a good idea to avoid both panniers and top boxes! The best way out of the speed wobbles is to gently loosen your grip on the bars, otherwise you end up fighting back and increasing the amplitude of the wobble.
Those used to modern bikes won't be impressed by the way the bike rides or handles but a well set up Z ridden moderately - as in posing, dare I say? - isn't too much of a horror story. Any pulling to the left or right, under forward motion or retardation, is a sign of a twisted frame.
Chassis bearings can be short-lived, especially those supporting the standard swinging arm. Anyone who wants to ride fast will have dumped the high, wide standard bars and forward mounted pegs in favour of flat bars or clip-ons and rear-sets - the reduced leverage makes the bike a bit of a pain in the tighter bends and town.
Surprisingly, there are many Z1's around that still have a good finish, the most obvious area of concern mottled alloy corrosion on the engine. The only way to clean the latter up's bead-blasting, which looks neat but makes the bike less than standard. Some dealers have clocked bikes, done a respray in the original colours, trying to pass old dogs off as prime meat.
Yes, just like in British bike circles, there are people who like to keep Z1's completely stock, right down to the original suspension. This is okay insofar that it means it's unlikely that the bike has been thrashed, because if used at speed it'd probably be run off the road! On the other hand, immaculate and original examples can fetch three grand, or even more if you buy from a dealer.
Mildly modded Z1's with over 50,000 miles on the clock go for around two grand, maybe two and a half. This ain't a bargain but such is the pull of the original model that prices are never going to be sensible. Unless you're really stuck on the Z1, it's best to ignore it in favour of the later models.
The Z900 shares the Z1's styling and engineering, and if you're desperate for authentic retro kicks could be resprayed in the original Z1's colours. Most Z900's have modded suspension, loud 4-1's and quite high miles on the clock, usually having been ridden hard.
Rough ones turn up for as little as a grand but may need major work - look for smoke out of the breather, naff gearchange action, top end rattles and intrusive secondary vibes. Something with a decent engine, non-standard suspension, and much modded induction and exhaust, goes for £1500 to £2000. Original bikes with less than 25000 miles on the clock fetch as much as £2500, sometimes three grand, in dealers.
The Z1000 turned up in 1977, the 900's engine bored out to give 1015cc. This didn't produce any more power but increased its spread, making the bigger bike feel a little softer. Weight was up 25lbs but handling, suspension and braking were slightly improved. This was fairly typical of the way motorcycles progressed back in the seventies - start off with a hot engine, add weight and make it less powerful with each succeeding model. Nonsensical, but there you go!
Anything with a little wear in its chassis will desperately need upgraded suspension and new bearings. Which basically means all the models on offer. Z1000's suffered a bit more thrashing than the 900's, having stronger competition from other big Jap fours, but still ran reliably for at least 50,000 miles. Most problems of the high milers coming from the top end - either valve guides, cam lobes or camchain.
Top speed wasn't much more than 120mph, but this can be increased with a loud 4-1 exhaust, K and N filters and carb rejetting - maybe as much as 135mph. Which definitely needs an alloy swinging arm and taut suspension. Fuel was surprisingly good at 50mpg average but conspicuous consumption of consumables didn't inspire.
Pay £1500 to £2500 for prime examples of the Z1000 and as little as £750 for the rat ones, of which there are quite numerous examples. Come 100,000 miles all kinds of interesting things happen - fuel tanks rusting through, wheel hubs cracking up, saddles falling off, electrical burn outs, etc.
By 1979 the Z1000 Mk.2 had replaced the classic stying of earlier models with a more squared off look, that wasn't to many tastes. The engine remained the same, save for electronic ignition and better materials used in the valvegear. This is probably the toughest of all the big Z's, many having managed a hundred thou, or even more. Vibration can get at the ignition module, though, but this is instantly apparent as it either works or doesn't.
Unfortunately, the Mk.2 was yet heavier, another 10lbs, to weigh in at an unfortunate 540lbs dry. This added stress to the suspension and bearings. It shared this weight with the Z1-R, which is perhaps the ugliest of all the Z's but further fuelled the madness by having 90 horses to hand! If the latter tended to be thrashed to an early death, the Mk.2 led a relatively easy life and many examples have survived into the nineties - £1500 to £2000 should buy something reasonable.
Maximum weirdness was reserved for the shaft drive version of the Mk.2, all 560lbs of the hulk. Shaft drive technology of the time wasn't perfected; ridden hard the back end became all crossed up and it was a quick trip to an off-road experience. Okay, the Z1000ST was really just a tourer but its use of fuel and consumables was so heavy as to bankrupt the dedicated traveller. About the only good thing going for them is that nice ones can be picked up for as little as £1500.
In 1980 there was a fuel injected version of the Mk.2, making a very useful 96 horses at 8000 revs, but still being a heavy old thing to chuck around. The disc brakes worked better in the wet and ridden sanely the handling could even be called good. Problems with the injectors, and their black boxes, mean these models aren't too popular - £1000 to £1500 - and some have even been converted back to carbs. Problems with the injectors are somewhat variable, some are okay others have huge holes in the power band and outright failure of the fuelling. Cheap spares are difficult.
In 1981 the engine was bored out yet again, to 1089cc. Power was pushed up to 108hp in GP1100 and Z1100 forms, which whilst thrilling enough did finally have an effect on engine reliability, whilst mass had a marginal decrease to 520lbs. The GP could be upgraded with better suspension into a relatively safe handler but the Z1100 was always a bit on the dubious side. A two grand touch for fine examples of the breed.
1982 was enlivened by the Z1000R, the infamous Eddie Lawson Replica. A 100 horses mixed with 500lbs sounded promising at the time, but the bike turned out to be a bit of a speed wobbler, despite some heavy duty suspension and brakes. An 140mph waltz with possible death managed only to sort the men from the boys. Most were thrashed to death in as little as 50,000 miles; can even take out their crank bearings. If you get lucky and find a nice example, expect to pay £2500 to £3000.
The American market had the pleasure of the shaft drive Z1100 Spectre, all 100 horses and 550lbs of it! Weird handling's its major drawback, but mild use means there is usually loads of engine life left in American imports.
If the weighty and powerful Z1100 became too much for many people, Kawasaki also offered their Z650/750 models. Originally, there had been a Z750 based on a similar bottom end to the Z1, but this was a Japanese market only model. The Z650/750 shared the same basic aircooled, eight valve, four cylinder layout but had no common parts with the bigger four and dumped - inexplicably - the gear primary drive for a hyvoid primary chain.
Although the 650 could run to 100,000 miles, a lack of oil changes could take out its main bearings in half that mileage and it was much more made down to a price than the Z1, reflected in its much cheaper cost. The Z650, despite still weighing 480lbs, was reckoned to have much better balance than the big Z's; it was certainly superior in its handling, minor suspension upgrades making it a good bit of kit.
Most original UK based 650's are getting a bit long in the tooth, but American imports have given the bike a new lease of life in the used market. No need to pay more than £1500; the old ratty ones go down to as little as £500, when both chassis rot and ruined engine internals will be a cause for concern. Good Z650's have slick gearboxes, lack of secondary vibes and a quiet engine without any smoke. Expect them to top 120mph and turn in 45mpg.
The Z750 never had the popularity of the 650, had an engine that could be dead meat in less than 40,000, more from general wear than any chronic problems. The Z750 eventually mutated into the worthy and reliable GT750, whilst the 1100 carried on as the GPz1100 for a few years. Indeed, the basic engineering lives on in both the GT and the Zephyrs, surely a testament to their original design. Many elements of the engine inspired the watercooled GPZ900, which caused a massive storm back in 1984 and eventually evolved into the magnificent ZZR1100.
The big Z's can still be ridden on the pace by someone with more bravery than sense, whilst their general toughness makes them prime purchases for anyone after unusual durability and quality.
Dick Lewis