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Thread: R47

  1. #1
    Still Wondering mika's Avatar
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    R47

    The July American Motorcyclist has a nice piece on the the inside back cover about the BMW R47 1927-28.
    Pass the mustard and UP THE REVOLUTION!

    St. Paul Pioneer Press , Minneapolis Star Tribune

  2. #2
    Cannonball Rider #52 darrylri's Avatar
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    Yeah, I read that article. It's nice to see old Beemers get some print.

    But the article's a bit of a screamer.

    Starting with the 500cc overhead valve motor from the R37,
    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.

    engineers added a simpler frame and suspension,
    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.

    and stripped off unnecessary electronics.
    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.

    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).
    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 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.
    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...

    So, it was great to see such a nice bike in a national publication, but...

    (And no, I didn't send this to the AMA.)
    --Darryl Richman, forum liaison
    http://darryl.crafty-fox.com

  3. #3
    Focused kbasa's Avatar
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    I moved this over to the Vintage forum.
    Dave Swider
    Marin County, CA

    Some bikes. Some with motors, some without.

  4. #4
    Still Wondering mika's Avatar
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    The Paul Harvey Version

    I knew if I posted this it would get some critical attention, "the rest of the story" as Paul Harvey would say. I keep learning about our brand bit by bit. Thanks for some more of the story.
    Pass the mustard and UP THE REVOLUTION!

    St. Paul Pioneer Press , Minneapolis Star Tribune

  5. #5
    Cannonball Rider #52 darrylri's Avatar
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    I was looking at this thread again for some reason, and thought I might elaborate on the controls. Here's a photo "from the rider's perch" of my 1928 R52, as it was when I bought it 2 years ago:



    As you can see, this fully modern control layout would be easy for a modern rider to adapt to. In fact, in some ways, it's more convenient than a modern bike.

    For example, to start the bike, just open the fuel petcock (under the tank on the left side) and hold down the tickler button on the carburetor float bowl top (also under the tank someplace on the left) until some gas runs out of the carb. Now, retard the spark about a third of the arc of the thumb lever on the left handlebar and open the air lever and fuel lever about half way. There's no key, so just find the kickstart lever that swings out on the left side of the bike and kick away!

    Now, once the engine is running -- with those settings, it's running pretty fast! So, close the air completely and the fuel nearly completely, and adjust the spark advance so the engine sounds smooth.

    Although modern bikes always have their headlight on, the 60 watt (peak) generator can barely keep up with the 35 watt incandescent headlight bulb unless the motor is really spinning. So, you probably don't run the headlight unless you need it. But just in case you might need to, you can turn the headlight on by twisting the big knob on the back of the "drum" headlight. This conveniently also turns on the 8 watt taillight. And you can use the mechanical hi/lo lever to pull the cable that runs inside the headlight, where the actual hi/lo switch is safely protected from the elements.

    Now you're ready to be off! So, first, pull in the inverted clutch lever -- just like a modern bike! -- and then reach to the shift lever on the right side of the gas tank with your right hand and pull it up into first. Now open the air lever most of the way and the fuel lever about a half -- those are the two thumb levers on the right handlebar -- while simultaneously advancing the spark lever -- left handlebar -- to match the increasing engine speed. As you judge the engine speed is correct, gradually let the clutch lever out... And you're off!

    Pretty quickly you hear the engine starting to race, so it's time to shift into second. Simultaneously pull in the clutch lever, retard the spark (both on the left side) and close the air and fuel levers nearly fully. Quickly reach down with your right hand and push the shift lever with authority past neutral and to the stop, in second. Never mind about that grinding feeling as it goes into second, because second gear is not in constant mesh. It'll slide into mesh when it's ready! Now, don't dawdle or you'll lose your momentum: open the air and fuel, advance the spark, and let the clutch reengage. You've done it!

    Don't get cocky, now, downshifts are trickier. Oh my gosh! There's a red light up ahead at the next signal! The front brake is where you expect it (except for that inverted lever) but you better get an early start on braking. And to get the rear brake, you lift up your right foot off the floorboard and pull it back until you get your heel resting on the brake pedal. The rear brake has more force than the front, which is ok because with the hardtail suspension and minimal travel in front, there's not a lot of weight transfer. When the bike gradually comes to a rest, pull in the clutch and shift down. If you need to stop or slow quickly, BMW recommends you use the kill switch, to get some compression braking, as well as the hand and foot brakes.
    --Darryl Richman, forum liaison
    http://darryl.crafty-fox.com

  6. #6
    Registered User burnszilla's Avatar
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    Excellent Darryl! That should be an article in the Owners News.
    Stephen Burns - 2007 R1200GS
    BMW MOA Lifetime Member
    www.burnsmoto.com

  7. #7
    Focused kbasa's Avatar
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    A video of the starting drill and some on bike footage would be enormously informative.
    Dave Swider
    Marin County, CA

    Some bikes. Some with motors, some without.

  8. #8
    Still Wondering mika's Avatar
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    Thanks. I like learning like this.
    Pass the mustard and UP THE REVOLUTION!

    St. Paul Pioneer Press , Minneapolis Star Tribune

  9. #9
    Cannonball Rider #52 darrylri's Avatar
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    I just bought this book on Amazon. Early Motorcycles: Construction, Operation and Repair is a reprint of a book that was first written in 1916, had a second edition in 1920, and this is the 2nd printing, in 1924 with some updates of the time. I'm having a great time reading through it.

    The things we write about on the internet, are in the book, too. Here's a section on general maintenance, with topics like "What to do every week" ("Add distilled water and test your storage battery, if your machine is electrically equipped.") and "What to do every Two Weeks" ("Flush the motor with kerosene.") and so on, including yearly items ("Have your dealer take the motor apart for cleaning and inspection... This attention is sure to mean a smooth running motor for the next season.")

    Try this on and see if it doesn't sound familiar: "One of the most important considerations, making for efficient action and promoting long life of the mechanism, is to provide proper lubrication. The lubrication of the power plant is the most serious proposition. The best oil is the only kind that should be used, as more good motors have been ruined by the use of lubricant of improper quality or insufficient quantity than have been destroyed by accidents."

    But then it continues... "When oil is introduced to the engine crankcase by means of a hand-operated pump ... which means that lubrication is directly under the control of the rider, one pumpful of oil, every 8 to 10 miles, at speeds of 20 miles per hour will be sufficient. For a speed of 30 miles per hour, it will be necessary to inject a pumpful every 5 or 6 miles."

    Keep in mind that this book covers the newest models of 1924, one year after BMW began production, and 4 years before the R52 above came out. What a marvel of engineering the BMW must have seemed, with its closed loop oiling system, which not only didn't leak, it didn't drip by design, either.

    One final quote: "One thing which has given motorcycles and motorcycle riders a great amount of undesirable publicity is the fact that some riders persist in riding with the muffler cutout open. This may have been excusable in the early days of the sport when some motors were not powerful enough for even ordinary touring conditions, and the rider because of this fact opened the cutout to relieve the back pressure caused by the inefficient mufflers of those days. The Harley-Davidson muffler is a very efficient piece of mechansim and causes no appreciable back pressure in the motor."

    Plus ?ºa change, plus cÔÇÖest la m?¬me chose.
    --Darryl Richman, forum liaison
    http://darryl.crafty-fox.com

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