73 Moto Guzzi Eldorado Piston/Cylinder Options

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

  1. MotoGuzziEldorado

    MotoGuzziEldorado Wrench monkey

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    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 Been here awhile

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    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

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    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 Been here awhile

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    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
  5. fadingfastsd

    fadingfastsd Been here awhile

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    I was definitely bummed to get rid of it. Unfortunately I didn't have the money to put into it at the time, so it sat in boxes for awhile. I moved from San Diego to Colorado, and decided to sell the project rather than take it with me in pieces. I'll get another one, hopefully sooner than later.

    What do you have?
    #45
  6. xdsbiker

    xdsbiker Been here awhile

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    1973 Eldo, bought new in 1973. Racked up over 85,000 miles, and discovered it had a broken ring. Bought another one with 25,000 in it, swapped the engine and trans. Put another 15 - 20,000 miles, and retired it.
    Completely stripped the replacement bike, and kept everything except for the frame, wheels, and fenders. So...have two of almost everything to pick thru for the rehab.
    #46
  7. xdsbiker

    xdsbiker Been here awhile

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    Got it completely apart yesterday, so will repsint the frame, and work from there.

    Attached Files:

    #47
  8. xdsbiker

    xdsbiker Been here awhile

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    Heading to San Diego next weekend for a week of bike riding, but might try and rent a motorcycle for a day or two.
    #48
  9. fadingfastsd

    fadingfastsd Been here awhile

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    That's awesome, good luck on the rebuild. Will be a great project I'm sure. Plenty of places to rent motorcycles in SD. I'd recommend getting into the canyons out in East San Diego county, some great riding out there! Sunrise highway up to Julian is alot of fun as well. If I still lived there I'd have a an extra bike or two sitting around and join you!
    #49
  10. fireflyr

    fireflyr Been here awhile

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    XDsbiker, I'd be interested to see what you come up with, if you don't mind keeping this thread up. I'm going thru the same thing right now. As a matter of fact I need to source a new cylinder head too because of the damage caused before the PO tore it down. Thinking maybe detonation too.

    h1.png

    h3.png

    I'm looking at pistons, cylinders and one head. Plus all the other stuff that goes along with it. The bike is currently running an Ambo 750/4 speed that I have no history on. It runs great but I can't seem to get the front crank seal to do it's job. This will be attempt #3....... I must be folding the lip over on assembly.

    s1.png s2.png
    #50
  11. xdsbiker

    xdsbiker Been here awhile

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    Will keep the thread alive with posts now and then, and the rebuild progresses. One the original engine, had the cylinders bored about 25 years ago, got some new pistons, and had the heads reworked. Now to figure out if all that stuff is ok to use. The replacement engine still runs OK, so will prob just reuse that one for now. Was going to change both crankcase seal on the engine, and the input and output shaft on the trans, so how to not have the same problem you are having. Will be sourcing what parts are available from MG Cycle, cuz they are the closest. So far, Greg B's website and detailed breakdown photo's have been great. Off on a work project for a day or two, but will post some photo's over the weekend.
    #51
  12. Scudman

    Scudman Been here awhile

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    I may have a spare head for the Eldo if you are interested. The cheapest spares are located in Germany http://www.stein-dinse.biz/Moto-Guzzi. You will need a decent size order to offset the shipping cost but a set of cylinders should do it. You can bump the size up to 944cc as they are available. Also you can use the cylinders for a 1000cc motor by shaving the cylinder skirt by 1mm. The motor may have a bit more vibration due to an imbalance.
    #52
  13. fireflyr

    fireflyr Been here awhile

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    I'd be interested in the head. PM me and we can work that out. Thanks.
    The bike had 18,000 miles on it when a/the PO pulled the engine in 1984 (!!) and it sat until last year when it was re-assembled with the Ambo engine. The cylinders don't look too bad but one of the pistons looks like the head. The cylinders are chrome plated so they are going away. I will look at Stein-Dinse and figure out the best route. Thanks.
    #53
  14. fireflyr

    fireflyr Been here awhile

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    17EAAF2A-6918-43F0-A318-A9A8092FD392.jpeg Looks like both the heads are toast. Looks like the cam chain tensioner failed and may have screwed up the timing. Pistons and cylinders look ok although I’m still replacing them.
    9F4EEAB2-4253-4BA5-A0E3-92AD9C93B14C.jpeg
    5065A292-9855-4BA5-8B4A-969B8827BBCD.jpeg
    So I’m still looking for a set of heads. Any of you wise Guzzi Gurus know if the heads on the Ambassador 750 engine are the same heads? Any alternative heads work? Thanks.
    Pat
    #54
  15. fadingfastsd

    fadingfastsd Been here awhile

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    Sorry I can't be of much help. What caused all that pitting on the heads around the valves??

    Sent from my Pixel XL using Tapatalk
    #55
  16. fireflyr

    fireflyr Been here awhile

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    Here’s another picture of the failed tensioner. 07E81707-ED54-46DD-99B3-B40C745E15A4.jpeg
    #56
  17. fireflyr

    fireflyr Been here awhile

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    From what I understand it’s detonation when the timing goes off. That horrible pinging noise. Correct me if I’m wrong.....
    #57
  18. fadingfastsd

    fadingfastsd Been here awhile

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    Ya that makes sense. I'm sure that would do it. All this Guzzi talk is really making me miss my old bike. I gotta find another one?

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    #58
  19. xdsbiker

    xdsbiker Been here awhile

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    Pics of the heads off the original Eldo 850 engine. Don't know if they will fit, but one pic includes the casting #. These heads are from the Eldo's original engine, and were resurfaced some time ago, and have been in a bin since then waiting to be re-installed...
    Checked "Guzziology", page 4-14 and it lists that a similar head is used on "The Eldo, 750S, V7 Sport, V7 Special, 850 GT, and most (almost all) Ambassador."
    Hope this helps. Note in the pictures that the heads do have some minor pitting.
    So fireflyr - might have a spare set of heads to get rid of. Will know in a couple of weeks, when I get around to pulling the heads off the spare engine. Gizzi head 1.jpg guzzi head 2.jpg guzzi head 3.jpg
    #59
  20. xdsbiker

    xdsbiker Been here awhile

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    Got all the parts off the frame, and am trying to decide if it's best to have it sandblasted and powder coated, or spend the time and labor to wire brush the frame, and repaint. Got a quote from a local shop of about $250.00 for the sandblast and powder coat, still need to get a price on some paint.
    Noted the frame had some rust spots, so started to wire brush the frame to see how bad the rust was, and it cleaned up fairly well. Will prob end up wire wheeling the whole frame to make sure all is OK, then decide - powder coat or paint...
    Also ordered a bunch of carb parts from MGCycle.
    Now that the bike is fully apart, there is a open parking spot in the garage! Room for the V85???

    Attached Files:

    #60