Monday 4 January 2021

Kawasaki Z1000ST

Like most old Japanese fours the Z1000ST had many good and bad points. Even when brand spanking new it wasn't  a perfect machine. Time, mileage, cack-handed maintenance or rebuilds, after market accessories and crash damage all take their toll. As many Kawasaki fours will be 20 years old anything and everything can be expected and suspected.

Many of the bikes were raced, even the ST shaft version! The most obvious mark being the oil plug wired in (though this is cheap enough to replace with a new one). Race madness burnt the clutch and would ultimately ruin the top end and roller bearing crank, although the latter took some doing. Being descended from the Z900, the 1000’s are extremely tough, even better built than smaller fours like the Z650.


The tough four cylinder motor churned out more than enough power to be interesting, well up to speeding on modern roads. The engine had a wide spread of power that was usually focused at 6500 to 7000 revs by the fitment of a four into one exhaust. An obligatory fitment given the rate at which the OE system rusted.

The ST was aimed at the tourer but had the extreme penalties of even more mass than the already heavy chain drive Z1000 and excessive consumption of consumables. Tourers didn't expect race track handling and welcomed the maintenance free shaft drive - in theory. The ST wasn’t on offer for very long, its parameters having a very limited appeal.

Appeal though it did to the guy I bought the bike off. He’d run it for 15 years and 45000 miles, with no engine problems and lots of chassis upgrading. In fact, the bike ran later Z1100 forks with massive brace, Koni shocks, Avon tyres, and an heavy amount of frame bracing around the steering head. The frame was in reality quite well built, crash resistant to the point where it'd only bend when the bike was a complete write off.


The riding position was stock, raised bars and forward mounted pegs. A refilled seat with kinky leather cover proved comfortable but the high bars were a turn off for high speed work. Anything over 80mph. caused pains just about everywhere and my helmet almost tore my head off at the ton. The chassis, thus modified, was much better than I had any right to expect. None of the infamous weaving or wallowing, showing that by 1979 Kawasaki had more or less sussed the dynamics of steering geometry.


Weight was a severe limitation in the bends even after I'd fitted ape-hangers to aid leverage. They were not well matched to the chassis with a tendency to increase the effect of the secondary vibes. They really buzzed between 5000 and 6000rpm, even more of a frenzy above 8500 revs. I'd read in the UMG that the solution was to squeeze tubes of silicone sealant into the ends of the handlebars. I did this and it helped a little, but obviously if it doesn’t work you're left with no easy way to remove the goo.


The commendably loud four into one exhaust, with its obvious benefits for personal safety (even if you end up deaf), had the major drawback that it dug into the tarmac on spirited right-handers. At this point the Michelins felt like they were about to fall off the edge of their tread so | should’ve just taken it as a warning to back off. Sometimes, in the company of friends, it was necessary to turn the wick up and then the limits of the big Z began to intrude.


Now, there are ways to overcome this which involve lots of muscle and a big pair of balls, some very vicious point and squirt techniques. The shaft drive, normally well in the background, began to intrude, especially under braking or a trailing throttle when the back wheel hopped across the road. It's a very tiring experience, both mentally and physically, that after half an hour leaves me flaked out.

The brakes can also affect the chassis, maybe down to the non-standard front end, more likely to some weakness in the swinging arm or mounting, and to wear in the forks themselves. The lack of gaiters inspired no confidence in the seals’ longevity, whilst the mixture of twin disc braking forces and excessive mass must've given the bushes a real battering. Being forced to chuck the brace to stop chronic stiction didn’t help their resistance to twisting.

If the effect, at times, was a touch traumatic the splendid way the motor ran overcame most of my reservations. My friends on water-cooled fours were experiencing early cam wear, camchain demise, burnt out clutches, seized pistons, etc., whilst the Z just ran relentlessly. Those on race replicas bore a remarkable resemblance to gorillas, resulting from their unnatural posture, hard seats and stiff suspension. They seemed to take any excuse for a petrol stop whilst I could quite happily potter along at 80mph for 200 miles; easily catching them up during their series of stop/go routines over the same distance even though they reckoned a 120mph cruising speed a minimum rate of velocity.

The Z showed its age by seizing up the rear disc and by the silencer disintegrating. The former needed work from a big hammer whilst the latter was just a matter of sawing off the remnants and fitting a can off a GPz750. The relative silence revealed that the set of eight valves were in desperate need of shimming, which I decided to do myself with the aid of a Haynes manual. Not easy, it took me a whole weekend of fiddling with shims and camshafts. Despite, at that point, having done 54000 miles, there was no sign of wear, something to do with regular oil changes, I think.

Not long after that hassle the steering went really vile, traced to a pair of worn out taper roller bearings in the headstock. These were seized in so solidly that a blow torch, drift and lump hammer were needed. The new set proved equally resistant to a few words of pep talk. I actually ruined the top one trying to get the thing in. After a weekend of the usual swearing and sweating, the Z was back on the road.

It took six attempts to torque down the steering head. Too tight or too loose had the handling all vicious; needed a surgeon’s touch. A second session was needed once the bearings had bedded in, but after that excessive hassle they settled down nicely. The handling was progressively becoming rotten despite this act of charitable effort, the hard pressed forks taking all the pressure from wild riding and, also, just the mass of the bike. I'd heard about someone who was breaking a Z1100, so went along to have a look.

I was harshly interrogated before being admitted into the presence of a perfect specimen, save that the crank had broken. The front end was as non-standard as my own, coming from a Zephyr 1100 and having done only 3000 miles. Mine for a £150 but I'd need to buy another set of taper rollers as the steering stem was different, which pissed me off as I'd have to go through all the effort and hassle again.

It was worth it. Like being on a brand new bike by way of comparison. It was still a great handful, still did some massive wobbles, but for a lot of the time it'd become a perfect peach. The increased steering accuracy and stability actually gave me the means to set the bike up on a line that avoided the harsher of the bumps and pot-holes.

This relative bliss lasted for all of four months. I’d had some near misses, of course - who hasn't? - but a bloody big bus running through a red light at about 50mph was more than I'd expected in my worst dreams. I’d actually slammed on the anchors, given the Z a shoulder dislocating lurch, missing the back of the bus by inches. My new trajectory and remaining velocity took me up the pavement and into a brick wall. Such was the residual momentum of the Kawasaki that the rotted bricks exploded, the wall collapsed and I head-butted the plate-glass window that was previously held in position by the destroyed wall.


The window exploded on my helmet, shards of glass causing the peds to scream and run around like headless chickens. Luckily, injuries were minimal but when I staggered upright I found that the Z's front end was ruined. By then the shopkeeper had rushed out to view his wrecked building, a few more bricks falling down from the side, threatening the structural integrity of the upper storeys! By then the bus was nowhere to be seen and my explanation appeared very weak. The cops thought so, too, and the insurance company weren't over the moon at the prospect of rebuilding the shop, plus loss of earnings, nervous distress, etc., for the shopkeeper.

As it was only TPFT cover I ended up knocking on the old front end after doing a quick rebuild with new seals and bushes, plus hard chroming the sliders. This was nowhere near as good as the previous set-up, the forks are just too spindly for the mass. Having become used to reasonable handling, the second time out had me off the bike for the first time. Somehow, before I’d always managed to hang on, come what way. But this time I hit a pot-hole when I banked over that I thought I was going to miss by six inches.


The suspension just couldn't cope and the front wheel tucked under the bike, the whole thing swinging around like a fair ground ride. Only there was no safety bar and I went flying one way, the bike the other. There’s urban warfare for you, boy. The tarmac was harsh on my knees and even uglier on the Z, which managed to rip its fuel tank off and spill petrol everywhere.


Some Hurray Henry rushed out of his cage wearing a vicious grin, sprayed the bike, myself (who was trying to ward him off) and a couple of gawping peds with a fire extinguisher. He thought himself a hero, I thought him an arsehole and would’ve booted him between the legs had I not been busy wiping foam out of my eyes.


By then the Z had 78 thou on the clock and was feeling as tired and pissed off as I was with life in general and this motorcycle in particular. It had to go before it killed me. I bought a used tank which turned out to be more rust than metal, and a few other cosmetic bits, to put the thing into good order. Z1000s are very popular, I didn’t have any trouble selling the bike for a small profit. A used Zephyr 1100 was bought as a replacement, a real dream in comparison but still enough of a bruiser to be interesting and keep me on my toes in the corners.


Giles Montgomery