Final: BMW R 90 S

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Final: BMW R 90 S
Jahn

Final: BMW R 90 S

Give rubber, cow!

Being able to move a BMW R 90 S today is a godsend. Open your eyes to a completely different way of driving a BMW. A trip back to a time when boxer engines were still creaking and moments were still working.

BMW had a problem in the early 1970s. It came from Japan, had four cylinders and was called the Honda CB 750 Four or Kawasaki Z 900. Machines that had significantly more steam than the pitiful R 75/5 with which the Munich-based company vied for top-class buyers. In addition, the Japanese were about the same in terms of price. And of course they had a much sportier appearance than the aforementioned touring boxer.

A solution was sought in Munich, and the result was not only a significantly improved / 6 series ?? finally also with a five-speed gearbox ??, but a real top model: the sensational BMW R 90 S. What an appearance: The first machine in the world with standard handlebar trim, hump seat, elaborate paintwork and a sporty 38-inch Dellorto carburetor. That sparked in the brains of the biker community, BMW was someone again. In addition, the new engine with its thick 90’s pistons produced a whopping 67 hp and was thus finally up to date in terms of performance. And that with just two cylinders and a VW Beetle valve control via bumpers and rocker arms. If you look at an R 90 S like this today, you start pondering. BMW was actually able to build lean, pared-down machines once. The lines are clear and soft, the engine, fork and two struts are almost delicate – that’s what it actually does. Today’s boxer BMWs are technically almost going crazy. Paralever, Telelever, ABS, injection, four-valve, many chains. But there are almost twice as many environmentally friendly produced PS.

When the starter bangs hard on the flywheel and brings the 35-year-old boxer to life, the world changes. The engine, with its large flywheel mass, is bubbling away in idle gas, bubblubblubb, you can’t buy that for a lot of money from a BMW dealer in our times. And certainly no longer the patented elevator effect when accelerating. The old lady gets out of bed, as if she wanted to give the driver a better overview because of the relentless acceleration. Yes, yes, the R 90 S accelerates quite well. Under five seconds to 100 km / h was a good value in the 70s, the BMW manages to 160 km / h in a short 12.6 seconds. And while we’re on the numbers: It ran 198 km / h with the driver sitting upright, which is not part of this story today, because despite modern tires, the R 90 S oscillates quite violently from 180 km / h.

Time travel

In terms of driving, you have to think back to the old days on the BMW. On those days when engines still had a flywheel and chassis still had a life of their own. And on top of that, the R 90 S has enduro-style spring travel and the erection torque of the cardan drive. Anyone who has not largely agreed on speed and the desired radius before the bend will quickly notice how valuable driving with a steady hand can be. Having to correct an incline once on the BMW means a dramatic sagging of the hindquarters with a simultaneous loss of ground clearance. Depending on the inclination, this can end badly. So, always slowly before the bends, put in the right gear and then with a full pull and thus a lot of ground clearance around the corner. Whereby engaging a gear is not so easy. Shifting needs to be really learned thanks to long shift travel, ultra-sluggish clutch and the flywheel, which somehow develops a life of its own. Only the expert can shift the gears of such a BMW quietly. At the beginning there is an embarrassing crash in the gearbox, after a day or two there is flow and a little pride in your own driving skills.

Where you shift 80 times with a Japan 600 file, the boxer grumbles with maybe eight shifts. The flywheel makes you comfortable and ensures a certain balance on the throttle. Hectic Not an issue on the R 90 S. But temperament does. Yes, it’s actually quite astonishing how wildly the old boxer clicks over the 7000 sound limit on the wobbly rev counter. There really is joy. The two-cylinder in the air filter box growls pithily, the pots creak loudly into the world. It’s remarkable how such an old bumper construction works. And in the process, for example, downgraded a modern F 800 motor to a sewing machine. No, no, no, it wasn’t all bad back then. We break a lance at the boxer and ask ourselves: Why don’t the people of Munich build a modern, air-cooled two-valve boxer instead of the boring parallel twin? Classic mistake! Trample your own tradition, that’s not how it works. No one can tell me that this black painted Rotax twin with its compensating flail would be cheaper to produce. Maybe borrow an air-cooled 1100 Desmo from Ducati, that’s awesome, right??

Stop! The nag went through with the author. Where were we? Oh yeah, not at all. Because the BMW doesn‘t really brake. It just gets slow a little faster. Anyone who came up with this braking system still belongs in the penalty corner today. A cable runs from the hand lever to the master brake cylinder under the tank, from which the two brake lines then lead to the brake calipers. Typical case of adding disadvantages of two types. Sluggish elastic cable with expensive hydraulics. Well Modern machines always brake better. Thank God. Break. Let the engine cool down and take it easy on your wrists. Just the age. Or why can you suddenly no longer pull the clutch? Maybe because you don’t have the constitution of a lumberjack from the Bavarian Forest. That was because he was responsible for the interpretation of the gear ratio of the clutch lever. And also put an infinitely hard disc spring into the dry clutch. Peace to his ashes. Where is the tube with the ointment for tendinitis??

Driving experience

It continues over the winding landscape of the Swabian Alb. And always nice in the fifth. You don’t have to switch. Even from the lowest engine speeds, the boxer purrs up again. The Dellortos were injected quite passably. Only those who have gross motor skills on the throttle can make the engine swallow. Enjoyment comes up. Because the suspension of the BMW is so infinitely comfortable. Because the boxer grumbles so fed up. Because the sitting position is so comfortable. And because the small cladding provides adequate protection. Sports tourers would be called the R 90 S today. She could keep up in this class. Also thanks to the classic gear train with 19-inch front wheels and narrow 4.00 H 18-inch tires at the rear. You will look in vain for the trailing of uneven ground and longitudinal grooves that is common with the current wide tires on the R 90 S. It irons almost everything smoothly and glides neutrally even over fourth-order streets, qualities that are mostly missing these days.

Speaking of quality: the paintwork was sensational. How the jewelery color harmonizes with the silver background is wonderful. Add to that the hand-drawn decorative lines, what would that cost today? It should be noted positively when the stickers on the tank have been painted over. The great workmanship of the R 90 S can currently hardly be bought as standard for a lot of money and good words. The tachometer, which often indicates pointless stuff, would go to the trash. Be that as it may: 17,465 BMW R 90 S were sold in total. That was more than BMW dared to hope for at the time. And sometimes up to 60 percent of the total sales of the / 6 series. Now the boxer bubbled sonorously while standing still. Twice the throttle boldly, engage first gear, and the BMW sweeps away. The fully accelerated boxer can be heard creaking for another 30 seconds. Give rubber, cow! May you lift yourself far too much out of bed for many years to come.

Technical data – BMW R 90 S

Engine:
Air-cooled two-cylinder four-stroke boxer engine, crankshaft longitudinally, bore x stroke 90 x 70.6 millimeters, 898 cm3, 49 kW (67 hp) at 7000 rpm, 75 Nm at 5500 rpm, electric and kick starter, dry clutch Chassis: double loop frame made of tubular steel, telescopic fork, two spring struts, cardan drive, double disc brake at the front, drum brake at the rear, spoked wheels, 3.25 H 19 and 4.00 H 18 tires.

Measurements and weight:
Wheelbase 1465 millimeters, with a full tank of 235 kilograms.
price(1973): 9130 marks including ancillary costs (4668 euros)

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