Kawasaki GPz750e Turbo Review: Staff Bikes

Date 19.9.2012

Presented by
  • Motorcycle Trader

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Kawasaki GPz750e Turbo

They say timing is everything. There we were, cruising the classifieds, when something literally jumped out of the page at me. A Kawasaki GPz750 Turbo (aka ZX750E) in top condition, with just 25,000km on the clock. Really?

A recent windfall had seen muggins happily frolicking down the acquisition trail but the money had just about run out. We really couldn’t afford this one… bugger. Maybe if we put off a few luxuries like food and power, plus an elderly relative’s heart operation, we could manage it.

Where many folk have a ‘bucket list’ of things they want to do before they die, I have a liability list – bikes that must at least spend a little time in the shed. A factory turbo was on it.

For those of you who came in late, the Japanese factories, at a time when they were undertaking a particularly fierce rivalry (early to mid 1980s), decided to try turbocharging. The attraction was obvious – lots more power from a modest engine size. The results were mixed and ultimately the idea failed in the market, though the entertainment factor was enormous.

Over the years I’d ridden all the other factory huffers: Honda CX500 and 650, Yamaha XJ650 and Suzuki XN85 (also a 650). For some reason, however, the Kawasaki had slipped through the net. Frustratingly, the GPz was also said to be the pick of the breed.

A little polite negotiation and the owner agreed to exchange prisoners: he got all the cash I didn’t really have while I got the bike.

Kawasaki was the last of the Japanese factories to produce a turbo, which had advantages and disadvantages. The advantage was it got to sit back a little and try to avoid the mistakes made by others. On the negative side, by the time they rolled out their toy the market was well on its way to deciding that turbos weren’t such a great idea.

So what were the issues? The biggest was the competition from the makers’ own catalogues. A full-sized conventional 1100 had a better spread of power, was almost as fast on top-end acceleration and was far less complex. And none were game to release an 1100 with a turbo – probably just as well, given the questionable chassis available at the time.

By the time Kawasaki launched this machine (1984), turbos had a reputation for being soft on low-end power and often for having an unacceptable level of turbo lag (the delay between nailing the throttle and the engine responding). Mr K’s response was two-fold: provide a bigger 750-class engine; mount the turbo on the headers, at the front of the powerplant, so there was minimum delay to pressurisation. By most reports, it worked.

That was then – what about now? The turbo had been sitting for a few years, so a comprehensive freshen-up was called for. New fluids went in (oils and brake fluids), a new battery and fork seals. The latter had perished, possibly through lack of use. We also tossed the tyres, which were replaced with Pirelli Sport Demons.

A quick note on the rubber: the Demons seem to suit this era bike quite well. Grip is fine for general use, though I have noticed they can feel a touch ‘nervous’ on directional stability until they’re thoroughly bedded in.

With a little trepidation, we turned the key and hit the starter for the first time. It fired up for a few seconds and promptly died. Then it stubbornly refused to play. Go back to it the next day and it starts, runs for a little while, then dies again. Fuel starvation perhaps? Nup. The pump was working fine and the injection was definitely getting petrol. Air blockage? Nup. Ignition? Ah…

Here’s a weird one: the igniter box under the seat had a crack in its casing. This is one of those times you learn to love the internet. Z750Es are rare at the best of times and parts can be hard to find. However, a surprisingly modest fee paid to a wrecker in the USA saw a replacement unit in my hand in about a week. It plugged straight in and solved the problem.

Finally, 28 years after launch, I get to ride a Kwaka turbo. Thank heavens I haven’t had to buy all my test bikes in that time…

What’s it like? Surprisingly little and low. The air-cooled engine feels and sounds pretty agricultural by today’s standards and doesn’t really do much to impress as you tiptoe your way through the traffic. It’s okay, but I’d much rather have my 1980 GSX1100 in these circumstances.

Eventually we find enough room to play. The first time it gets wound up I get so engrossed in watching the turbo boost gauge that I completely forget the tacho and speedo. So we’re screaming near redline at some hideous speed. Did that really happen? We try again, watching the correct clocks this time. Jeezuz H Kerrist!

This is Dr Jekyll and Mr Hyde with wheels. One minute it’s a rather gruff mid-weight, the next it smoothes out, picks up its proverbial skirts and rockets at the horizon at an unbelievable rate. Around 5000-6000rpm is where the transformation takes place and it really is dramatic. Suddenly it starts to feel a little like a modern performance bike.

A bloke I know, Harold Holt (no, not that Harold), was a Kawasaki salesman at the time these were launched. He owned a GPz1100 and reckons the turbo had more acceleration. I believe it.

So what’s the catch? Definitely the 1980s chassis. The frame holds together well enough, but the combination of clip-on-like handlebars with very heavy steering is weird at city speeds. It comes together better at highway pace.

The centrestand is a damn nuisance, restricting cornering clearance. My biggest beef is with the brakes. They’re just not up to the job and feel a good 10 years behind the performance. You really have to think twice about where you cut loose the engine as the stoppers are easily overwhelmed.

In its day, the Zed claimed a 220km/h top speed and 11.5sec quarter mile – very respectable numbers, particularly for a ‘mere’ 750. There is more performance readily available via a remarkably simple mod. The popular theory is that Kawasaki didn’t want this bike to overshadow and outperform its soon-to-be-released GPz900R, which was a far more important model in the grand corporate scheme.

So, the stock turbo was restricted to 10.5psi boost. That apparently more than doubles if you unhook the brown wire from the engine management unit in the tail. This, with one or two other subtle mods, is supposed to switch the tuning to ‘race’ mode and we’re told the difference is staggering. If only you could do the same with the brakes.

The turbo Zed is far from perfect but it does the one thing any bike worth its petrol should do, which is put a dirty great grin on your face when you ride it…

SPECIFICATIONS

Kawasaki GPz750e Turbo

ENGINE

Type: Air-cooled, two-valves-per-cylinder, four-stroke, in-line four-cylinder

Bore and stroke: 66m x 54mm

Displacement: 738cc

Compression ratio: 7.8:1

Fuel system: Electronic fuel injection with turbocharger

TRANSMISSION

Type: Five-speed, constant mesh

Final drive: Chain

CHASSIS AND RUNNING GEAR

Frame type: Twin-loop steel

Front suspension: 37mm conventional fork, adjustable air preload with adjustable anti-dive

Rear suspension: Monoshock, adjustable air preload and rebound

Front brakes: Single 280mm discs with single-piston calipers

Rear brake: 270mm disc with single-piston caliper

DIMENSIONS AND CAPACITIES

Dry weight: 233kg

Seat height: 780mm

Fuel capacity: 17lt

PERFORMANCE

Max power: 82.4kW (112hp) at 9000rpm

Max torque: 99.1Nm (73ft-lb) at 6500rpm

Top speed: 220km/h

OTHER STUFF

Price: $4900 (in 1984)

Test bike supplied by: Guido

Warranty: N/A