I find it amusing that things should turn full circle, so to speak. The manufacturers would have us believe that the only way to go was watercooling, four or more valves per cylinder, mono-shock and more high tech wizardry than you can shake a stick at.
Yet here we are again, and Kawasaki by no means alone, with a relatively simple across the frame air cooled four with a mere two valves per cylinder, and a pair of twin shocks stuck out back. The little 550 Zephyr at least sports a new frame unlike the 750 which looks like nothing so much as an upgraded Z650. Which hundreds, perhaps thousands, of UMG readers will chorus, is no bad thing.
The Zephyr is in fact based on the Japanese 400 model with which it shares most its chassis. The engine is similar to the well known GPz550, although not so extravagantly tuned for top end power. The GPz in its last years was easily burnt off by any number of hot-shot 600s but was reliable, fast enough to be interesting and surprisingly economical when not pushed to the redline all the time. Unfortunately, the new 550 shares few of these virtues.
It seemed fitting to compare the new 550, which has its roots in the early seventies, with another Kawasaki, the GPZ500 twin, a machine of the late eighties with a thoroughly modern engine and chassis but one paying at least lip service to the concept of economical transport. The GPZ is also based on a Japanese model, the GPZ400S but unlike the 400 Zephyr, it is a machine designed to be practical fun rather than appeal to the nostalgia crowd.
You will probably already have read a lot in the glossies about these new universal Japanese machines bringing back the joys of sensible riding, etc., etc and the manufacturers hoping to pick up lots of buyers who have held on to their older fours. Well, forget all that crap. There is very little in the Zephyr that could be classed as progress. Admittedly, the frame is better than most of the seventies stuff, the swinging arm a robust alloy job with eccentric adjusters will have the aftermarket people swearing their heads off at the lost sales and even the four into one exhaust might have vendors worried until it falls apart from rust.
The suspension is still not very good, worse than that fitted to the GPZ which at least has the good grace to feel taut until 5000 or more miles are on the clock. Don't get me wrong, the Zephyr isn't in Z1 or H1 country, but it's certainly a less stable and less flickable bike than the old GPz550. This has nothing to do with the old fashioned twin shock set-up but is merely down to the usual lack of damping control, even though the remote reservoir shocks look the business.
Similarly the meaty 39mm forks could do with both tauter springs and damping. Strangely, the 37mm units fitted to the GPZ500 feel better, at least until you slam on its single disc......the Zephyr stops as well and as predictably as you could want using its twin front discs. The rear disc also works, after a fashion, but is infinitely inferior to the plain old SLS rear drum on the 500.
The smaller twin is, surprisingly, a tad faster than the four (125mph against 120mph), and also needs less use of revs and gearbox at lower speeds, producing a useful amount of torque below 7000rpm. Only at very low speeds does the Zephyr impress in the smoothness of its transmission, despite the chain primary drive, compared to the graunching noises out of the GPZ box if you try to do 20mph in top gear. Both machines could lose one, or even two, gears out of their six speed boxes with little detriment to performance.
The GPZ500 feels stable and flickable, giving the lie to the idea that all bikes with 16" wheels are twitchy numbers. It does need a pair of Metzeler or Avon tyres after the original Dunlops have done 3000 miles, when they become most dubious.
The Zephyr lacks the same kind of secure feel and needs more effort to flick through bends, it may improve with better tyres, a wide choice available as it runs on a 17" front and 18" rear wheel. True to its heritage, the 550 needs upgraded suspension to remove the twitchiness experienced in bumpy bends. The few owners still running their middleweight fours on the original suspension would be impressed by the 550 and overjoyed by the 500.
Both bikes have well proven engines. The 550 good for around 60,000 miles (in GPz550 tune) before serious work is required. The watercooled twin will at least equal the aircooled four in engine longevity, having the added benefit of constant engine temperature.
Maintenance requirements are minimal for both machines, each able to take neglect just so long as frequent oil changes are done. The watercooling system on the GPz requires hardly any attention so can not really be accused of adding to the complexity.
Interestingly, the smoothness of the twin, with its pistons moving out of phase (thus giving perfect primary balance) and a gear driven counterbalancer taking care of any crankshaft torque reaction, is superior at ton plus speeds to the four which lacks any means of damping out the slightly intrusive secondary vibes at high revs.
The twin is decidedly lumpy at lower revs and occasionally sheds pillion footrests, but has a delightful howl from the exhaust when it's thrashed, unlike the four which is as bland as any other middleweight multi.
Style is a matter of personal taste, but it has to be said that the GPZ's half fairing provides sufficient protection to cruise along at the ton all day long whilst the naked Zephyr with its less than perfect riding position is uncomfortable above 80mph. If your licence is in danger this may be no bad thing. Tall riders will be disconcerted by the high speed wind blast off the GPZ's screen and cramped by the riding position of the Zephyr, although the latter can at least easily alter its handlebar thanks to a tubular rather than cast item.
Long distance cruisers will be disappointed by the quality of the Zephyr's seat padding, anything more than 150 miles is not recommended. The 500's seat is one of more comfortable around. Combine that with better fuel economy and a bigger fuel tank for the watercooled bike to win out as a long distance tourer. It's almost BMW like in its poise!
At first glance the difference between average fuel consumption is not that big. Around 56mpg from the twin, 48mpg from the four. What that hides is the fact that the Zephyr will not respond to slow riding with much better than 50mpg whilst the 500 does as much as 65mpg. Who cares? All those people who have to use their bikes as commuting machines as well as weekend fun mobiles. No-one has bothered to look at the possibilities of tuning the 550 engine for economy. It is less economical than the GPz550, which is obviously a ridiculous state of affairs.
Both machines share the usual silly features - tiny front mudguards, exposed fork seals (all the more galling as the GT550 has gaiters), no full enclosure of the chain, etc., etc. And both machines lack enough power to give real grin inducing, neck snapping acceleration.
The GPZ500 impresses with its riding experience and the Zephyr with its nostalgic style. If the twin had the Zephyr's swinging arm and (decent) twin shocks it would be a complete motorcycle. If the Zephyr had a single carb, the twin's brakes (with a fork brace), upgraded suspension and a better seat, it would be a very useful multi. Out of the showroom, the twin wins - but then I'm biased as I used to own one!
Dick Lewis