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748 2000 748r - From Disaster To Full Rebuild

Discussion in '748 / 916 / 996 / 998' started by TelRobinson, Feb 9, 2019.

  1. :rolleyes:
     
  2. With the pots still on only gotta measure piston height for bent rods .
     
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  3. I've fixed loads of engines that have dropped a valve or two, where there is a large bit of metal occupying the same space in the squish area....not a single one of them has had a big end gone or a bent rod etc.
     
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  4. Only bent rod I have come across is a water ingestion, hydrologic lock.
    Steve
     
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  5. I assume you have found the 2 broken bits of valves. ???
     
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  6. The damage on the exh valve looks like historic erosion over time by heat. Probably by being around the spark plug area where the flame area is strongest and hottest.

    The damaged areas aren't shiny or new in comparison with the rest of the valve.

    Fuelling issues may have played a part.
     
  7. I
    My thoughts exactly but the fact that the exhaust cam won't turn indicates contact.
     
  8. This had a bent rod...

    pist2.jpg pist8.jpg pist9.jpg
     
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  9. You can see the contact (poss. ally) on the outer edge on the exh valves (furthest away from plug) along with a slight bright mark on the corresponding part of the piston pockets.
     
  10. my point is you cant just stick a couple of valves in it and put the head back on.. it wants stroke squish and CR checking and i would probably go with a bore polish/hone/clean up and new pistons..... maybe even a 853 opportunity? might even be cheaper

    good info here..

    http://bikeboy.org/853rstuff.html
     
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  11. also whats going on around the top of the inlet valve pockets? are they all like that sir?
    Screen Shot 2019-02-12 at 17.55.06.png
     
  12. Doh....
     
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  13. Ah, my favourite little troll - I read the words 'Inlet Valves Chipped' so I added the part numbers to be helpful.
    I do however find it hilarrrrrious that you of all people didn't spot it having clearly studied the photos and replying in the mean time :joy: quite pathetic really, maybe time to give up trolling all my posts as it doesn't look like you will ever win :(
     
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  14. ;)
     
  15. I can't believe no-one has mentioned valve guides either!
     
  16. On what is a thoroughly interesting thread bringing the investigative and technical expertise which is what’s great here - can we leave the cheap shots out,just for once?

    If you don’t think you can do that and you think this applies to you then for all our sakes , step away from the computer for the evening and watch last nights Cold Feet or summat

    Cheers -from a keen learner.
     
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  17. I can't believe no-one has mentioned Ducati John.
    http://www.ducati-john.co.uk/

    Get it on a van and up there before you loose half the summer. (Just my opinion).
     
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