The 1970s was a pioneering era for bikes of all descriptions. It was a time of experimentation with the Japanese blazing a trail with in-line fours and sixes, pumped with carbs and bhp.

In the US the big Kawasaki’s had taken hold. Their bullet proof inline fours were a favourite on the drag strip. A nation that had grown up with a long line of V-twin motorsickles, the far-east invasion was seen as a breath of fresh air.

But as usual in the US, quarter-mile times were everything and people just wanted more. The 4-wheel drag racing scene was dominated by ethanol breathing supercharged V8s, but the standard Roots Charger was way too big for a bike.

The Turbo Revolution

Enter the lightweight turbo. A useful little exhaust-driven compressor fitted between the header pipes and the air intake could boost pressure inside the engine and therefore provide a bigger bang per buck and much more horses at the wheel. Great idea – in theory.

Car companies realised that the tiny turbo could provide a huge power increase on a standard engine. In Europe, Porche and, later, Saab had some success with clever, if somewhat complex installations in their vehicles, and so the news was out.

After the raging success of the Z1, Z900 and Z1000 the public wanted a new-look bike and the Z1R was launched in a blaze of glory with icy blue paint on its new-age chiseled lines, a cheeky nose fairing and a nod to racing with its 4-1 exhaust.

But the press soon uncovered that, despite its sharp new look and a bit of extra bracing, it was a rushed cosmetic overhaul of the previous model. On top of that, it handled like a pig, so tons of big Kwacks were left in the showroom with nowhere to go.

Enter the man with ideas

Former US Kawasaki Executive Alan Masek knew a thing or two about the big Ks engine. It was healthily over-engineered and quite roomy in its frame. In theory, it was an easy job. He that an American Turbo Pak unit slotted into the frame where the four big carbs used to hang, while they were swapped out with one big fat one off a Harley.

In place of the header pipes a big fat tube, nicknamed ‘the log’, piped the burnt gas round the back to the turbo. To stop things going pop, a waste gate would blow out at 10 pounds, hopefully avoiding pricey repair bills. With a straight-through pipe at the end, the whole installation looked kind of tidy – so garish paint was a must.

If we’re honest, the turbo was a bit too big for purpose which resulted in quite a lot of lag on acceleration but wound up above 4500rpm the horses came running home at a humongous rate of knots, and riders eyeballs would start to bleed.

The whole set-up was a bit crude, but with power boosted from Max to Max and a Half (135bhp) a big cheer rose from the drag strip as flames followed the bike down the quarter mile. There wasn’t a production bike or car that could match its 12-second 125mph runs in 1978.

Great on paper

But alas, all was not as it seemed. Buyers of the beast expected a bike they could ride, but this wasn’t so. To be brutally honest, with on/off power wrapped in a jelly frame, the Z1R TC was a nightmare on the road.

It didn’t go round corners, was a dog to start, it drank enough oil to keep most of Texas busy and the whole thing was a bit of a rottweiler. Docile, then completely insane.

On top of this, the turbo used SAE bolts but the space for the bike’s toolkit had reallocated to accommodate an electric fuel pump. The oil filler hole had been used for some return pipework which made any maintenance a pain in the neck.

Demo models had beefy welded cranks and a strengthened clutch but the standard buyer had no such security. Being a closed loop pressurised system there was no limit to the engine’s acceleration, flying past the red-line was a common experience, often encouraging the double overhead cams to bounce the valves into the piston crowns. Ouch! Plus the seat got very hot.

A good number did flow from the dealers, though, despite all these pitfalls and the extra price tag. But with some negative feedback about its brutal characteristics, a series 2 was launched after just one year with everything being tamed a little.

The new bike has its wastegate fixed at 6 psi, It had better oil plumbing, and a bit of subtle detuning made it a touch more manageable. Still, the recommendations stated you should beef up the clutch, weld the crank, fit stronger valve springs and lower the compression ratio. Ah, that’s all.

The beginning of a movement

The Z1R TC was only in production a couple of years but it blazed a trail for a hand full of factory copies from the Japanese manufacturers themselves. Honda beefed up the CX500 into a 650ccc flyer but its flabby new clothes never caught on.

Yamaha tried out a 650 Seca Turbo, but again the stylists had a bad day and the resulting wardrobe sold almost nothing while Suzuki produced a 600 that was just plain slow.

kawasaki-gpz750-turbo-01
The GPzTurbo was a refined machine and light years ahead of anything else in turbo form, but its hefty price tag was equal to the GPz1100, an almost identical machine in terms of performance but with much more kudos.

Kawasaki, armed with a lot of research material went on to produce the GPz 750 Turbo, a beautiful machine that got it just right. Fuel injected, tough components, matched gas-flow, and balanced delivery made it an awesome machine that could equal the GPz1100 which, at the time, was considered the king of the road.

But cubes rule and the 1100 won the battle.

End of an era

The turbo’s downfall was its complexity. Conventional bikes were getting lighter and more powerful and were a heck of a lot cheaper too. By the mid-80s the bubble had burst, only die-hard fans and customizers ventured into the blower territory after that.

But the legend lives on, and occasionally one of the iconic Z1R TCs will turn up at auction for absolute mega bucks – but only a crazy rich fool with a desire to die would dare take it out on the road.

CW