1. This site uses cookies. By continuing to use this site, you are agreeing to our use of cookies. Learn More.

748 Rocker Arm Condition

Discussion in '748 / 916 / 996 / 998' started by Andrew46, Feb 14, 2024.

  1. It's not mine, but a chap I know has started a bit of a restoration on a 748 that hasn't run for several years. He's taken the rocker arms out to see if they are flaking. They look in pretty good condition to us, no actual flaking, but not really sure what a knackered one would like. one of the shafts has got some scoring, is it excessive?
    Pictures of some of them below

    Thanks in advance.

    IMG_8458.jpeg IMG_8459.jpeg IMG_8460.jpeg IMG_8461.jpeg IMG_8462.jpeg IMG_8463.jpeg IMG_8464.jpeg IMG_8465.jpeg
     
  2. This is what my flaking follower looked like
    upload_2024-2-14_20-37-57.jpeg

    upload_2024-2-14_20-36-6.jpeg
     
  3. Would say a couple of them are looking a bit suspect. Or maybe the engine has been revved before the oil has got to the top end. Bit difficult to say how bad they are from photos
     
  4. To me the rockers in the first 3 pictures look ok. The other 2 look knackered. The rocker shafts looks definitely knackered.
     
    • Agree Agree x 1
  5. Thanks for the replies so far, very helpful.
     
  6. The oil feed to the valve gear was notorious, it would take some 90sec after cold start for oil to make it to the head.
     
    • Disagree Disagree x 4
  7. People get themselves in such a tizzy sometimes .

    Do they look like brand new parts ? ...... No , they do not ( of course they don't ! )
    Do they look like seriously worn or damaged parts ? ..... No , they do not

    But the choice is yours alone ..... put them back in and forget about it ,
    or buy all new components , and deal with the pain in the wallet .... :)

    We are talking about the engine in a motorbike here , not a jet fighter .
    ...... but that's just my two Drachmas worth ..... ;)

     
    • Like Like x 2
  8. And that’s a notoriously wrong statement…

    Video taken on a 748 horizontal cylinder. Motor hadn’t been started for 3 months before the test.

     
    • Like Like x 4
    • Useful Useful x 2
  9. Could just be the light, but there appears to be start of a flake on the first rocker. I always thought that if your fingernail could catch on a chip when you run it over the chrome, it's time to get it sorted.

    20240216_121006.jpg
     
    • Like Like x 1
  10. Hadn't noticed that :upyeah:
     
  11. Does that part of the surface, right at the edge actually run on the cam though?
     
  12. Oh yeah, so it is
     
  13. Some kind of myth we all believed in at some point. For me, personally, this video made a world of difference.
     
  14. The 4 valve 748 certainly had wear issues on the cam follower. These ones look mild compared to ones I've seen with the cam profile actually worn into the follower. Dodgy chrome if I remember.
     
  15. The EUrinal and their ' greening ' of things like hard chrome ( they are banning it completely soon ) no more chrome plating.
    Paint used to be good, but now with 'water based paints' that are frankly EUseless and needs repainting more frequently ( the germans in the last war didn't have the petrochemicals for normal paint so they created water based paint.
    They are now using the knowledge and patents to conquer the world using paint !
     
Do Not Sell My Personal Information