Schatzi
SCHATZI
A Porsche-Powered BMW That’s Ideal For All But The Faint Of Heart
Bob Atkinson
AFTER 20 YEARS of biking and 23 machines, Gerald (Jerboa) English decided to build his ultimate custom—a vehicle with the biggest, wildest engine practicality would allow. The result is a Porsche-powered BMW that is not only fast, but also tractable enough for city driving and touring in the country.
An automobile engine, even a Porsche, sounds heavy and clumsy. It sounds like an installation that would ruin the handling on any motorcycle. But in the case of Jerboa’s bike, none of these thoughts even remotely apply.
Mating of the 1638cc S-90 engine to the BMW transmission is professional. In fact, it looks like a factory job. What’s more, the Porsche sits low in the modified BMW frame, creating a favorable center of gravity. When the bike is leaned over at a stop sign, it isn’t any harder to right than a 650 Triumph. And why should it be? Total machine weight is only 470 lb. That’s right, Schatzi, as Jerboa calls his machine, is lighter than several so-called “super bikes.”
As mentioned earlier, the frame and transmission are BMW. Fitting the Porsche engine to this setup requires a special engine adapter. In addition, the internal gearbox ratios were altered by Leroy Searight to better suit the torque characteristics of the larger engine. At 65 mph in fourth gear, the engine now turns 1500 rpm; 100 mph is equivalent to 3800 rpm. Needless to say, you can exceed the speed limit anywhere without even straining the engine, which is capable of 7500 rpm as tuned.
The 1962 S-90 is close to stock internally and produces in the neighborhood of 100 bhp. The cooling fan, vertical oil cooler and stock carburetion setup were removed because they presented too high a silhouette. Cooling is now handled by a pair of power steering cooling units mounted at the head of an enlarged air tunnel under the gas tank.
Two carburetion systems were designed for the bike. For normal town driving, a pair of Honda 450 carburetors mounted on short manifolds provide good low end and mid range power. For high speed touring or drag racing, a single 45 DCOE-9 Weber carb is fitted to a special intake manifold of Jerboa’s own design.
Power is transmitted to the rear wheel via a BMW driveshaft and bevelgear assembly. The rear brake is also stock BMW.
To ensure quick stops, a Gremica double leading-shoe front brake, laced to a WM2 rim with standard spokes, was chosen for the front. The tire is a 3.00-18.
Front suspension is Ceriani. The square headlight, by Hella of Germany, and the instrument cluster are mounted to the top triple-clamp, which was modified slightly for this purpose. Gauges are amp hour, oil pressure, and oil temperature; all important for keeping a high-performance engine intact.
Handlebar mounted control items are for the most part identical with present day production machines. The two exceptions are the compression release lever and the rear view mirror. The compression release actually activates a Grover air horn, mounted under the fork crown. The rear view mirror is miniscule by anyone’s standards, but does comply with the law as written.
The foot shift lever, rear brake pedal, and foot rests are mounted “frisco” style, but not for trend. They are mounted high because conventionally mounted controls would be too close to the engine and its heat.
Since Jerboa has been designing and constructing fiberglass bike components for years, he decided to fabricate the seat tank combination for Schatzi himself. The unit was built from a mock-up of Lunsford Mud and then pulled off a splash part to be worked into the final shape. Sanding, priming, and applying acrylic lacquer completed the project.
The finished section is held on the BMW frame by a single T-nut. Another section consisting of the battery box, tool box, and rear inner fender form support for the weight of the passenger. Rubber pads, one under the driver and two smaller ones under the passenger, provide additional support for the structure. A nice touch: the fuel lines are of the quick disconnect variety to facilitate removal.
The upholstered portion with dual fiberglass backrests is held onto the seat/tank combo by two bolts. Dick Inez Upholstering covered the backrests after several shops said the shape made it impossible to upholster properly. This dual backrest set-up is unusual, but it does offer comfort rarely found on bikes.
There you have it. A two-wheeled Porsche for touring. Jerboa’s dream. Really, it’s a shame someone doesn’t produce a machine like Schatzi, because the crackle of the exhausts and the brisk acceleration leave a lasting and favorable impression. jo]
