Bmw Memo

BMW MEMO

BY SLONIGER

PHOTOS COURTESY BMW WORKS

YOU might say that the Bavarian builders of those motorcycles known as BMW’s got into the game by accident, but once in they showed a single-mindedness rare in the two-wheel game. Of course they had a solid model to start with and have yet to see a need to change the basic concept.

The founder of it all, motorcycle-wise, was a gentleman named Max Friz. This solid German type was building airplane motors back in 1912 and produced one of the leading German powerplants for the German WW I air force. They must have been good; an American who flew against them still remembers the insignia with a sort of reverse fondness. When the Armistice put an end to such games Friz needed work for the Munich factory and hit upon two-wheelers.

Consider the first BMW motorcycle a moment. It had a two-cylinder boxer (horizontally opposed) motor sitting east and west in a steel tube frame and the engine capacity was 500cc. A notable feature for 1923 was the engine output of 8.5 hp @ 3300 rpm, and it was a sidevalve engine, incidentally, By comparison the current half-liter BMW with a tube frame produces 26 hp @ 5800 rpm in its road tune and a husky 35 hp @ 7650 as the R-50 S, introduced last season. They still call that one a road bike despite its top speed of a round “ton” with the rider prone.

Of course they have hotter models, in the 600cc class, culminating in the R-69 S, another new item of 42 hp at 7000 rpm. You can do a hundred sitting up on this model, or better prone. That’s where better than 35 years of following the Friz road has landed them.

BMW, which exports nearly two-thirds of its bike production and a full 85% of the twins (because a crippling road tax at home makes it literally cheaper to run a small car), has gone from tube frames to pressed steel and back to tubes. They have bowed to the times with first front, and then the rear wheels sprung (for a while there, at the time of the first 250, employing a multi-leaf suspension unit) and they have even used blowers in racing but the basic idea was unchanged: One cylinder, sitting upright in unit with the gearbox, and driving the rear wheel by shaft instead of chain, or a twin with the same properties. The singles were almost universally of the quarter-liter persuasion though a few lines of 200, 300 and 350cc crept in during the Thirties. The twins wandered between half a liter and three-quarters, with a few 600’s along the way.

One of the most interesting to drive must have been the 750cc, ohv, 26 hp twin produced from 1941 onwards for a while. This R-75 was notable at first glance for its low, fat, auto-type tires and, upon closer inspection, for the fact that the sidecar wheel, in its normal position, was also driven.

Just for the record the first BMW bike motor, a twin of course, was not fitted in their own frame. It appeared in the north-south position in the Nurburg-built Victoria, which later got a boxer of its own, and then in the BFW “Helios.” BFW stands for Bayerischen Flugzeugwerke (Bavarian Aircraft Works) as opposed to Bayerische Motorenwerke, but the circle divided into blue and white quadrants was already in action. By the way, the Victoria used belt drive. The cardan shaft came with Friz’s first BMW of 1923.

Stiff frames lasted until the R-5 and R-6 in 1936/37. The telescopic fork reached Bavaria about 1935 and the rear telescopic spring leg got there with the R-5 1 of 1938. Both side and overhead valves were used through these model years, though they have gone over to ohv now. The blower models were specials and were never really a true part of the series. For that matter some pre-war models had either one or twO carburetors, with identical numbers, but these were exceptions. The numbering system itself is a little light hearted if you consider that they began with R-32 in 1923 and didn't get around to the R-3, for instance, until 14 years later (and a year after the R-5). And so forth.

Since the war BMW has concentrated on sidecar racing for the Sports side, though the heavy twins have won various German championships in trials work. The world sidecar title has been a house sinecure every season since 1954. Recent three-wheelers, notably Camathias’ home-tuned special from Switzerland, have run with injection too.

The current line consists of five bikes, the R-27 of a quarter liter, the two 500’s called R-50 and R-50 S, and the two 600cc machines, the R-60 and R-69 S. German DIN hp figures are, respectively, 18, 26, 35, 30 and 42, with speeds ranging from the 250’s 75 mph sitting to about 109 for the big boy.

You probably should include the pear-shaped Isetta automobiles in any family tree from BMW since they use the 250cc motor, while the short-lived 600 fourseater and the highly successful 700 sedans, coupes and roadsters use the boxer twin. Even with motorcycling on the drop in Germany, BMW has a strong export line and plenty of ideas on what to do with the basic product. They’ve had three and a half singleminded decades to work out an attack. •