73 Moto Guzzi Eldorado Piston/Cylinder Options

Discussion in 'Old's Cool' started by fadingfastsd, Nov 7, 2014.

  1. MotoGuzziEldorado

    MotoGuzziEldorado Wrench monkey

    Joined:
    Nov 21, 2014
    Oddometer:
    7
    Location:
    San Francisco
    Wow, thank you for posting this. I just restored a 1973 Eldorado and this is the kind of thing that keeps me up at night. Some observation that might help:
    - the two pistons have different rings, some work was done at some point to give old top end a new life (I am doing that myself!)
    - the blown one has all ring stuck.

    IF the rings stuck before the event, chances are you had low compression. That in turn will make the mixture lean despite perfect carb tuneup and perfect timing. At least that is the conclusion I would come to if this was my bike. The other piston has carbon deposit, it might be fine.

    What would I do? I would make sure the rings move freely in the groves. Then I would test the compression. You can loan a compression test tool from OReilly for $0 (they charge you a fully refundable deposit). I have done it, my old chrome lined cylinder were at 130/135psi, low but within acceptable range. I rode 100mi on them before one of them started to blister and the free ride was over. Anyway, anything approaching 100psi or less and it is time to rebuild.

    Hope this helps.

    [all reading this] BTW I am on the market for an Eldorado piston since I damaged one of mine during cylinder swap (I am putting iron sleeved cylinders on). PM me if you have one, please.

    Good luck!
    #41
  2. xdsbiker

    xdsbiker Adventurer

    Joined:
    Dec 31, 2016
    Oddometer:
    52
    Just started the rebuild / restore of my 73 Eldo yesterday, and this post came up when looking for cylinder parts. Lesson learned - don't let the fuel sit in the carbs for 25 - 30 years.
    How is you rebuild engine running?
    #42
  3. fadingfastsd

    fadingfastsd Been here awhile

    Joined:
    Feb 17, 2007
    Oddometer:
    283
    Location:
    Fort Collins, CO
    Oh man this was over 3 years ago, I totally forgot about this bike! I'm ashamed to say I never fixed it... I ran out of money and time, and ended up selling it as a rolling frame, motor out in pieces in boxes. Sold it in that condition for more than I bought it for, so I can't really complain. Was really bummed to let it go, but had other things going on at the time. Still looking for another Eldo/Ambassador now. Good luck with yours!
    #43
  4. xdsbiker

    xdsbiker Adventurer

    Joined:
    Dec 31, 2016
    Oddometer:
    52
    So sad you ended up selling, but money and time are always a problem when restoring. Thought many times about selling the old beast, or donating to a museum, but ended up keeping it. The plan was to start the rebuild back in 1994 when i purchased the SP3, but...time and money, work, and a family put it on the back burner. We'll see how it goes...
    #44