Newbie With 1991 Ducati 750ss In Yorkshire - Need Some Help!

Discussion in 'Newbies Hangout' started by TonyBourke, May 9, 2022.

  1. Hi, just bought a rough 1991 750SS.
    On tearing down the motor I discovered that the drive chain had previously smashed the crankcase and had been bodged back together.
    I’m managed to get some new cases at a reasonable price from Germany but also need piston rings for the front cylinder.
    The cylinder seems to be Nikasil plated?? Do I need to get a certain type of rings or would the rings from say a 750 Monster be ok???
    It’s the dry clutch model with HC on the outer clutch case....I’ve not seen many of these.
    Engine no. seems to be no.63

    image.jpg
     
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  2. Welcome to the forumTony.:)
     
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  3. Hello
     
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  4. Welcome. Hopefully someone who knows what they are talking about will be along soon :)

    ps. I’ve amended the thread title slightly so it should attract knowledgeable people :)
     
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  5. Welcome and enjoy.
     
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  6. Also might want to post something in the technical help and/ or relevant bike section, assuming you haven't already
     
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  7. Welcome. I too have a 1991 750ss and I get most of the bits I need from www.stein-dinse.biz. They have a load of diagrams so you can check out the part numbers. Last time I looked they had rings for a 750ss. I believe they are ithe same as 750 Monster rings.
     
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  8. Thanks Steve, I’ve done a bit of homework and agree that the 750 Monster has same cylinder and piston so I’ve gambled on a used Monster piston and cylinder
     
  9. Hi, I’ve received the Monster 750 piston and cylinder.
    The piston is different to the 750SS....lower compression by the look of it.
    I’m just going to use my old piston with the middle ring from the Monster.
    750SS piston on the left

    89AF8F63-3A59-443A-B7A7-3036435AC393.jpeg
     
  10. As @Steve Hoy says, it's worth confirming piston ring compatibility by part number if you can, as rings subtly different over the years, but belt SS/Monster around that time are all nikasil type cylinders just for starters.
     


  11. Thanks Chris
    Do Nikasil cylinders have cross hatching?
    My cylinders do and so does the one from the Monster
     
  12. they normally do, yes but I am generalising as this is a massive subject, and "re-honing" in preparation for new rings on a nikasil bore is another controversial area, as more harm than good can easily be done here, whereas this is a straightforward, relatively easy operation on a non-nikasil cylinder as you probably know.

    These are one of the "bench-mark" Companies when it comes to anything nikasil, and I think might be kind enough to advise you, if you are thinking of doing it yourself - might even be on the site in text-form. :upyeah::-

    http://www.langcourt.com/page26.html
     

  13. Thanks again Chris
    I’ve just been watching Andy’s Motorcycle Obsessions 900SS rebuild on YouTube.....his pistons are flat topped.
    Are my pistons non standard hi-compression??
    I thought they were standard
     
  14. can you see any sign of a manufacturer's stamp on the hi-comp piston? I'm sure others will be along to add more, but they look like they could be J.E. Banks aftermarket pistons. They loosely replicated what Ducati used on their earlier bevel gear engines. What's a bit curious is what looks like some abrading and removal of material on both sides of the piston crown which looks to possibly coincide with the edge of the squish band on the cylinder head.
     

  15. They’re stamped 09 3528 on the underside
     
  16. My first 750SS was the very same bike with "HC" clutch. :) Very small chance it's the same bike, but..
     
  17. originally traced to Mahle but

    on second thoughts, the link was a bit vague so maybe not. :upyeah:
     
  18. The reg is J698HRN
     
  19. not mine - would have been nice. :)
     
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