mika
Still Wondering
The July American Motorcyclist has a nice piece on the the inside back cover about the BMW R47 1927-28.
Follow along with the video below to see how to install our site as a web app on your home screen.
Note: This feature may not be available in some browsers.
Well, not exactly. They started off with the 500cc motor from the R42 sidevalve, which had a number of upgrades over the R32. And they used conventional cast iron cylinders instead of ones turned from billet steel, which is what the very expensive R37 had. The R47 also used the same conventional (for the era) 2 slide carb that the R42 did, rather than the special three slide carb on the R37.Starting with the 500cc overhead valve motor from the R37,
It's true that the frame was simpler (and stronger), and that they replaced the twin sets of leaf springs for a single set to suspend the front forks, but probably more importantly, they also gave the bike a real rear brake.engineers added a simpler frame and suspension,
This is a real laugh. The R37 had no electrics (or electronics) at all. There was a magneto to fire the ignition, and that was it. It's true that the R47 was offered without electrics as well, but it certainly didn't save any weight or power over the R37 setup.and stripped off unnecessary electronics.
Hmm, really? With a thumb lever on the left handlebar to control the spark advance, and two thumb levers on the right handlebar to control air and fuel, this is a modern control layout? Not to mention little things like the inverted clutch and front brake levers, the knob on the back of the headlight and the heel brake pedal for the rear brake. Don't forget to tickle the carb before you start, too.The R47 also shares another distinction with other BMWs of its era. It was among the first truly modern motorcycles, featuring [...] a modern control layout (with the exception of the hand shift).
While this is all true, the real sports machine that followed was the 750cc R63, which put out 1/3 more horsepower than either the R47 or the R57...The R47 was sold for two years, and served as the basis for the R57 that followed. The third-generation performance machine integrated a more powerful front brake and a more robust transmission into the R47ÔÇÖs proven design.