73 Moto Guzzi Eldorado Piston/Cylinder Options

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

  1. fadingfastsd

    fadingfastsd Been here awhile

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    Hey ADVers,
    I've posted about my Guzzi before. It's a 73 Eldorado:
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    I've had this bike on the road for the last 3-4 months. Put about 600+ miles on it, after a basic tuneup, carb rebuild, cables, etc.

    Unfortunately earlier this week, while commuting on the bike, I melted a piston on the right side cylinder. I was cruising about 70mph on the freeway (had been for 10 miles already), when it lost power. I then noticed my legs were covered in oil, along with the entire bike. My brother picked me up with his trailer, and we got it back to my shop in Carlsbad.

    A quick test revealed no compression on the right side. I pulled the heads and cylinders on both sides. The right side piston had a 2" hole melted through the top. The cylinder has slag from the piston melted all over it. The left side was intact, but is obvious the piston has been scraping the cylinder wall beneath the rings. These cylinders have sleeves in them already, they are not the original chrome bores. The pistons that came out of it have Moto Guzzi & Mondial stamped on them, they seem to be OEM pistons. At this point both sides need new cylinders, pistons, rings, and gaskets.

    I've talked to all the main Guzzi parts suppliers. I can get a full kit from Moto Guzzi Classics for $1200. I'm really on a budget and trying to do this a hell of a lot cheaper. I've heard quite a few stories online about using Volkswagen pistons and cylinder sleeves on these bikes. That sounds like a way cheaper option.

    Has anybody done this? Do you know what VW part numbers to use? Any cheaper ways to go about putting new pistons/rings/cylinders on this bike without spending over a$1k?

    Here's pictures of the damage, and the good side:

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    #1
  2. MZRider

    MZRider Neo-Luddite

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    Right off of the top of my head, I can think of two options:

    1) source a pair of original chrome bore cylinders with reusable pistons, have the cylinders replated (approx. $420) and buy new rings (approx. $125).

    2) source a pair of Convert/G5/SP/CX100 iron bore cylinders and pistons. Turn the cylinder spigots down slightly so they fit into the Eldo crankcase with adequate clearance. May be some pushrod clearance issues, so you might need to remove some material from the pushrod tunnels and/or use Convert, etc. (Tonti) rocker arms. Without rebalancing the crank, there might be extra vibration due to the heavier pistons. There's a set of Convert cylinder/piston sets on eBay at present for $600:

    http://www.ebay.com/itm/76-Moto-Guz...Parts_Accessories&hash=item5d50e927f4&vxp=mtr
    #2
  3. flemsmith

    flemsmith lurk

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    I have a set of new in box Gilardoni 850cc cylinders and pistons I bought for my T3 before I found out it already had a 1000cc kit in it. Been sitting for a coupla years, if you can find out whether they would work for your El Dorado, I don't figure I'll do anything with them.

    roy
    #3
  4. Nessman

    Nessman From the western slope of the bell curve

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    Same thing :clap

    I bought a set a while back for my T-3 figuring they'd dry up again soon. My T-3 is still in a pile....projects tend to have that happen.
    #4
  5. Wirespokes

    Wirespokes Beemerholics Anonymous

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    Roy - If fadingfastsd isn't interested, could you send me a PM? I've got a T3 with chrome bores I need to replace.

    #5
  6. MZRider

    MZRider Neo-Luddite

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    The Gilardoni kits are the same for the Eldorado, 850-T and 850-T3, so they will definitely work.
    #6
  7. realgone

    realgone Adventurer

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    And having those Gilardoni stamped cylinders should help with resale when it's time to let it go.
    #7
  8. fadingfastsd

    fadingfastsd Been here awhile

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    Thanks to everybody so much for the replys! I just wanted to drop a general thank you here first. I'm going to respond to individual messages w/ quotes after this.
    #8
  9. fadingfastsd

    fadingfastsd Been here awhile

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    Hey Roy,
    Thanks so much for the offer. Sorry for the late reply, I was out in the desert riding dirtbikes for the weekend. It sounds like these will work on my Eldo. I would love this set for my bike. How much would you like for them? I can send you a shipping label, and pay via PayPal or whatever you'd like. I'll PM you as well.
    #9
  10. fadingfastsd

    fadingfastsd Been here awhile

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    Good to hear! Hopefully these work out.
    #10
  11. fadingfastsd

    fadingfastsd Been here awhile

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    If the others don't work out, are you interested in selling these parts?

    I'm dropping the oil pan tonight and trying to find all the missing pieces. I'm going to flush the whole crankcase with gas before dropping the pan, hope to get all the shreds out.
    #11
  12. danedg

    danedg Horizontally Opposed

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    It's not the case I'd be worried about, it's the big bearings. Pull the sludge trap. The real story will be in there. Hell! The answer as to why it burned in the first place might be all packed up tight right in there....:puke1

    Let me go out and check those pristine parts again...I know the cylinders looked perfect, but I want to double check the pistons.
    #12
  13. danedg

    danedg Horizontally Opposed

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    You want to see the contents of the pan in all it's glory!
    Drop the pan....
    Shine a light on the mess and see if you have shiny specks. Run a magnet through the goop and see if you come up with steel bits. THEN dilute the pan with gas and strain through a paint strainer. That will give you a better idea of what happened and how to proceed!:deal

    This is like forensic guzziology and you only get one shot at it.
    #13
  14. vanislejay

    vanislejay Been here awhile

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    I've holed a few two stroke pistons from pinging/predetonation. Was your bike pinging on the highway?
    #14
  15. fadingfastsd

    fadingfastsd Been here awhile

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    Now that I think about it, yes for the 30 seconds before destruction I believe it was pinging.
    #15
  16. Scudman

    Scudman Been here awhile

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    You may want to check the distributor timing. It may have been timed wrong to the camshaft. You could still have the timing right on one cylinder but way off on the other.
    #16
  17. JonnyCash

    JonnyCash turd polisher

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    tontis have dual points, but loops have single, so I can't imagine having it right on one and not the other. Am I missing something?
    #17
  18. danedg

    danedg Horizontally Opposed

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    Enquiring minds want to know...:evil
    #18
  19. fadingfastsd

    fadingfastsd Been here awhile

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    I checked the timing when I first got the bike. It was dead on. I had over 600 miles on the bike since then with no problems until this, so I doubt the timing had anything to do with this failure.
    #19
  20. fadingfastsd

    fadingfastsd Been here awhile

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    Been super busy with work and didn't have a chance yet to drop the pan. I hope to do that tomorrow afternoon. I promise to update when I do. Last night I finally got everything else stripped off the bike (seat, gas tank, battery/tray, carbs/filters) so the motor is easily accessible now.
    #20