Mz's Big Step
MZ's Big Step
THE SKORPION'S TWIN-CYLINDER STABLEMATE MAY BE THE NEXT BSA
WHAT HAVE WE HERE? WHY, IT'S just the 1997 BSA Rocket Gold Star, is all.
“No way,” you exclaim, your mind reeling at the implications of this astounding piece of news.
“Yes way,” responds Petr-Karel Korous, MZ’s boss. And it just might happen, providing Korous can get the right deals done, deals that involve not only Yamaha engines for the present, but the promise of an all-new British-built desmo-valve parallel-Twin for the future.
Triumph may have had the charisma back in motorcycling’s golden age, but BSA had the commerce; for a long time the company, located in the Birmingham suburb of Small Heath, was the world’s largest motorcycle manufacturer. Then, the British motorcycle industry self-destructed and the Japanese took over.
And now, with the Japanese rocked by the knockout value of a powerful yen and the Europeans on a roll, there is great interest in resurrecting the spirits of the Great Old Companies, jacking them up, and sliding modern hardware under them. That’s where this bike comes into the picture.
We first saw it, you’ll recall, at last October’s 1FMA show in Cologne, where it was billed as the MZ Kobra. Like its Skorpion sibling, which has picked up design awards on both sides of the Atlantic, the Kobra is the work of British design partnership Seymour-Powell, which employed specialist E3ritish constructor Dave Pearce of Tigcraft to build the prototype/showbike.
The Kobra was launched with Yamaha TDM850 power, and that’s what this prototype is fitted with. But under a deal negotiated with Yamaha more than six months in advance of the launch of the Japanese manufacturer’s own TRX850 sportbike, Korous confirmed supplies of the TRX engine, with its distinctive 270-degree crank timing and sportbike tune, will be available for the Kobra. Korous believes that the way to establish MZ’s credentials as a big-time bike builder is to race the Kobra in Twins events around the world before it enters production in September 1996, ready for the 1997 model year. MZ’s aim is not only to acquire some sporting heritage for the Kobra, but also to hold customer attention until a new Al Mellingdcsigned-and-built engine—originally designated to power a post-rotary Norton-comes online.
Since the launch of the Kobra prototype, MZ’s R&D staff has been converting show model into streetbike. To do this, they’re using a development hack fitted with a twin-spar frame, rather than the ultra-distinctive largediameter tubular steel chassis the Kobra was launched with. It seems the twin-spar frame is easier to experiment with and change in response to feedback from MZ's test riders. Every bike manufacturer does the same kind of thing, but normally you never get to see, let alone ride, these R&D prototypes. We did both.
The man in charge of developing the final version of the chassis is development engineer and former MZ works enduro rider Horst Lohr, who right now is busy building up the first preproduction bike in the newly-constructed Kobra frame jig. He's using 2.3-inch round tubing instead of the elliptical-shaped steel tube used in the prototype. The reason for this change is purely practical-round tubing has a greater stiffness-to-weight ratio than oval tubing.
Lightness is important. Says Lohr, “We plan to build the bike as light as possible in finished street form. The Yamaha TRX850 weighs about 415 pounds dry, and we are planning to at least equal that with a bike that has more complete bodywork. Reducing the weight of the chassis is a factor in achieving this goal.”
Like the Skorpion, the Kobra chassis incorporates the oil tank for the drysump Yamaha engine in its frame tubes, but Lohr has had to rework some of the prototype’s detail design features for production-offsetting the cantilevered shock to give room for the battery box, for instance, and switching from Paioli to WP suspension after supply problems derailed the Italian manufacturer.
The biggest change Lohr made to the original design was to lengthen the wheelbase from 55.5 inches to 57.1 inches-quite long even for a slantTwin sportbike.
Lohr explains, “We’ve tilted the engine another five degrees further forward than in Yamaha’s own chassis to throw more weight onto the front wheel to improve front grip, and we’ve also had to create more space for the radiator than the original prototype had. But by fitting a longer swingarm, we’ve kept the engine in the same position relative to the wheelbase as before, and the head angle is the same, at 26 degrees.”
Riding the Kobra prototype proves that Lohr got his sums right. This is a very capable sportbike, needing only a little further refinement to become an excellent one. The thing that’s most impressive is the good compromise achieved between high-speed stability and fast steering in tighter turns. As I chased Korous along his favorite backroad, the bigger, heavier and longer Kobra proved almost as nimble as his Skorpion.
It’s especially stable under braking. The floating 12.6inch cast-iron Brembo discs and four-piston calipers are the Italian company’s topof-the-line versions. They help the Kobra stop magically well from high speeds.
The settings on the multiadjustable WP forks were just right, without excessive dive under that kind of stopping power, yet with enough response to smooth out all but the worst patches, ripples and potholes that remain as a last vestige of East German Communist neglect. In spite of the fact that the fuel tank is mounted quite high, the center of gravity of the bike feels quite low. It doesn’t tip into slower corners too suddenly, nor does it shake its head if you hit a bump flat out in top (fifth) gear, cranked over in a fast sweeper. The WP fork and cantilevered shock deliver excellent ride quality, matched by a high level of response-low-speed damping is especially good. And in spite of the fairly conservative front geometry, the Kobra steers very precisely.
The TDM engine is a willing partner for this fine chassis, and the TRX engine, claimed to be 11 horsepower more powerful in stock form than the TDM’s, will be a much more worthy ingredient in the final package, especially with the close-ratio five-speed gear cluster fitted.
So it seems that the twin-cylinder sportbike market is about to be expanded with a new model quite different in character from the TRX850 Yamaha it borrows its engine package from. Korous believes his company’s bike, which will be priced in Germany at the equivalent of about $14.300, can compete directly against the machine from which it derives its powerplant.
Ah, but what about the new engine and the BSA connection that may be lurking in the future? The engine, drawn-up by British cylinder-head guru Al Meiling, could be a real barnburner. It uses desmodromic valve gear with three camshafts per cylinder, as on the first Ducati desmos in 1956-58. One cam opens intake valves, a second closes the intakes and opens the exhausts, and the third closes the exhausts. This reduces torsional loads on the cam and allows much higher rpm and much more radical cam grinds than otherwise would be possible. Balance shafts to quiet the inevitable quaking of a parallel-Twin? You bet-providing this engine does indeed get built.
The only other question is this one: What name will the finished product carry on its fuel tank? Will the next 12 months see the Kobra spring into the marketplace as a BSA Rocket Gold Star, the British marque’s most sporty Twin of yesteryear?
The key to that question lies in the outcome to Korous’s ongoing negotiations with the Aquilini family, Canadian entrepreneurs who presently own the Norton factory-having acquired it from financier Nelson Skalbania-and, with it, the rights to the BSA name on motorcycles of 200cc and up. Norton, which planned to use Melling's engine in VTwin form as a lifeline to the future, is about to go under, finally, with the apparent blessing of the Aquilinis. This leaves the Meiling engine without a home. MZ already is linked to the British-based BSA-Regal Group, which owns the rights to market BSAs under 200cc, to build a line of 125cc BSA bikes (see Roundup, August). But the sporty 125cc BSA Barrakuda won’t help MZ attack the large-capacity market. Negotiations are underway between MZ, the Regal Group and the Aquilinis. Says Korous, “We’re sorting out some way we can work together.”
If agreement can be reached, the Kobra will become a BSA, and join the new Triumphs in a further revival of once-great British names.
Alan Cathcart
