R80 v R100 engines ... how are they different?

Discussion in 'Airheads' started by bikecat, Jan 4, 2012.

  1. Hawk Medicine

    Hawk Medicine Coyote's Brother

    Joined:
    Jun 8, 2008
    Oddometer:
    3,304
    Location:
    NOR CAL
    If you do a search you'll find that the Siebenrock kits have a very good reputation. Matter of fact, I can't recall ever reading or hearing a complaint about Siebenrock's quality. Cost, yes. Quality, no.
    #21
  2. fishkens

    fishkens Long timer

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    Nov 14, 2009
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    5,360
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    Seattle, WA
    I installed Siebenrock pistons and the engine runs quite a bit smoother. But I also balanced the rods and did quite a bit of other work so Siebenrock can't take all the credit.

    Bottom line: a properly tuned, freshened and balanced airhead will run much better than a tired one. Not a lot of science there.
    #22
  3. Rob Farmer

    Rob Farmer Long timer

    Joined:
    Aug 27, 2002
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    6,751
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    Loughborough, Leicestershire. England
    I have a R100 Bitsa that Richie Moore did the heads on. It's running 9:1 pistons and his one piece valves running in F1 technology valve guides all setup with Groks Harmonizer. It has to be one of the smoothest airheads I've ridden and pulls like a train. Lovely!

    I've got to admit I'm not a big fan of the 80 motor and prefer the extra grunt you get from the 100.
    #23
  4. Caddy82rats

    Caddy82rats Long timer

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    Mar 8, 2007
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    Location:
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    What I can compre :
    R80 G/S best engine for smooth
    Just after my ex 77 RS, my ex 79 RS not so good
    and my 90S not so smmooth a litel rough... but so sexy !
    #24
  5. wmax351

    wmax351 Been here awhile

    Joined:
    Mar 13, 2011
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    Marin County and Berkeley, CA
    I personally really like the large flywheel. Smooths things out a lot, for any bike. My R75/5 is very smooth, even without any additional balance blueprinting. My uncle's EV11 Guzzi California was also very smooth, with 1100 cc's in a 90* vtwin. The cali has a ~35 pound flywheel, iirc.
    #25
  6. Hawk Medicine

    Hawk Medicine Coyote's Brother

    Joined:
    Jun 8, 2008
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    Yeah, the heavy flywheel tends to mask the vibrations but not only are the vibes still there somewhere but the engine won't wind up as quickly and the transmission won't shift as well.

    I've always lightened my flywheels and these days I'm happy not to have one at all. :wink:

    Horses for courses I suppose.:trp
    #26