BMW cunning on helmet storage

Discussion in 'Battle Scooters' started by vortexau, May 6, 2011.

  1. vortexau

    vortexau Outside the Pod-bay

    Feb 18, 2008
    Just off the Warrego, S.E. Queensland
    I doubt that Yamaha's system wastes very much power, but then, ALL motor balancing systems use moving mass and so, take a little bit of HP when the engine's speed changes. Would YOU prefer the vibrations of an un-balanced motor?

    Going by that diagram, its not really "wasting space" as its stuck in the middle of other components.

    There is (as you call it) "a moving powerless piston" running from a third crank throw in opposition to the forward twin-cylinders.
    You have to be talking with the Yamaha engineers on that point.

    My take is that its quite a good way to balance a horizontal parallel twin engine. The Flat-Four (VW, Subaru, and early Goldwings) is usually a very smooth, vibration-free engine design.

    A boxer twin can be fairly smooth but fore & aft cylinder mounting usually requires the barrels be higher than the transmission or the whole assembly may be just too long:
    1914 ABC motorcycle.

    1920s Douglas.

    Helios powered by BMW M2B15 engine (1920-21).
  2. btcn

    btcn Long timer

    Jul 1, 2010
    Morgan Hill CA

    It just seems a little wasteful to me. I guess it works great, and if so its not a big deal.

    It just seems to me they could have done something else. The Burgman 650 is also a parallel twin and it doesn't have a dummy cylinder for balance.

    I wouldn't want an unbalanced motor. But a little imbalance is ok with me.

    But what ever works for them, I know Yamaha engineers aren't stupid and I'm sure they have some good reason for it.