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

748 A Whirring 748s Engine

Discussion in '748 / 916 / 996 / 998' started by Geoffhogarth, Jun 23, 2018.

  1. My big end bits arrived to-day so I can get started on the engine rebuild, funny though, according to the description on the packet label, I am now working on a Plane :)
    IMG_2084.JPG
     
  2. Oh dear, can’t spell plain - American influence ??
     
  3. Geordie
     
  4. New Blue big end shells and screws installed to-day.

    IMG_2085.JPG

    New shells degreased and installed in rods and caps, ready for clearance check using old screws torqued to spec.
    IMG_2086.JPG IMG_2087.JPG IMG_2088.JPG

    Plastigauge inserted as per their instruction sheet, caps torqued up to spec, then removed again.
    IMG_2090.JPG IMG_2091.JPG

    Plastigauge measured and clearances found to be in spec :)
    IMG_2097.JPG IMG_2098.JPG IMG_2100.JPG

    Everything cleaned up again and lubricated with new engine oil. Caps refitted with new screws and torqued to spec with Moli grease on threads and below heads.
    IMG_2102.JPG

    Next step, dummy run of gearbox installation..........
     
    • Like Like x 3
    • Useful Useful x 1
  5. Impressive
     
  6. I usually assemble the bearings with a good quality Moly-Grease instead of oil for better lubrication before oil pressure is achieved and it means it can sit for along time and be rotated during assembly and fitment without fear, I also use grease on cams and followers etc. Nice job so far anyway.
     
    #126 NZDave, Sep 2, 2018
    Last edited: Sep 3, 2018
    • Like Like x 1
  7. To-day was a good progress day.....
    635A9366-66E8-4F63-978A-999B2C117DB7.jpeg
    9DB0B192-F1E1-443E-A3D2-87BCBFDCFFA1.jpeg D0FF8317-43A9-4A2E-B30B-9BE0DF03EA20.jpeg 5EFB1789-A8ED-4BAA-90ED-B02E2AB54848.jpeg 839DBFAB-85F7-459D-AF33-668FEBB4A7E9.jpeg
     
    • Like Like x 8
  8. Now ready for the next stage of the rebuild image1.jpeg image4.jpeg ....
     
    • Like Like x 5
  9. I was sorry to read that your main bearings went and also the investigative work to get that confirmed. But I am pleased you've got it sorted. On a selfish note I read your journey with interest and learnt a few things about these twins and the resources needed / available (just in case my Multi does one). Its really nice to see everyone help and the technical contribution was fantastic. Mounting the engine on its own stand in engine plates is a nice luxury, good job, thanks for sharing. :upyeah::upyeah:

    As an aside what would you have done if the plastigauge had shown too much / little clearance.

    TB
     
  10. Thanks for that mate, well most likely look at a crank regrind or a replacement engine. Anyway, getting there now

    D7382D27-7074-469D-A99B-49A4C50331C1.jpeg
     
    #130 Geoffhogarth, Sep 13, 2018
    Last edited: Sep 19, 2018
    • Like Like x 6
  11. Getting the engine back into the frame.

    IMG_2216.JPG IMG_2217.JPG IMG_2218.JPG IMG_2219.JPG IMG_2221.JPG IMG_2222.JPG IMG_2223.JPG IMG_2224.JPG IMG_2225.JPG IMG_2226.JPG IMG_2228.JPG
     
    • Like Like x 1
  12. Record the mileage (recent clocks), and the finished item :)

    Thanks for the tips from within this forum, and a special thanks to Bikeboy and Ducati John for passing on some expert knowledge.


    IMG_2240.JPG IMG_2242.JPG
     
    • Like Like x 3
  13. Good job.

    Compliments on the comprehensive workshop facilities.

    TB:upyeah::upyeah:
     
    • Like Like x 1
    • Agree Agree x 1
  14. Great job Geoff. I'm dead impressed with the 'Heath Robinson' engine lift, brilliant ingenuity.

    The whole thread is so informative. However, what do you reckon caused the main bearing failure? The fact someone had installed the clutch bearing spacers incorrectly in the past?
     
  15. Thanks for your comments, no I am sure the clutch bit was not at fault, and really surprised that did not cause any other issue. The previous owner had the bike for over 4 years, he says the clutch basket was never disturbed!
    The engine did showe signs of being opened before, so I recon it was possibly some debris from a previous failure of some kind. But when you look at the pic of the main bearing posted a while back, [​IMG]there there was definately something in it, however only one of the ball bearings was damaged so was that the culprit I wonder, hard to say.
     
  16. The engine lift makes it a bit easier I would imagine, I lifted mine in by hand on my own with a bit of swearing along the way.
    Well done and thanks for the write up, you don't mention hitting the starter button for the first time.
    Steve
     
    • Like Like x 1
  17. Thanks for that, well I'm a bit old at 67 with a weak back, so had to have a good plan.
    Well when it was filled with oil, it was buzzed over with the plugs out to get the oil around the whole engine. Put air box and tank on loosely. When hitting the start button, the oil light went out straight away, a good sign, the engine fired up and was ticking over until the engine temp got up to the fan kicking in around 190 deg F, I let it do that 3 times, prior to it cooling down, pulling the belts again and re-rorqueing the heads.

    After retorqueing the heads and once again putting it back together, the engine was warmed again as previously, then the new oil and filter were dumped for yet more new oil and filter.
     
    • Like Like x 2
  18. Yes I know where your coming from regarding age, my stronger years are behind me now, 66 next month, I've been re-timbering a roof this week with no scaffold, my back aches now.
    Steve
     
    • Like Like x 2
  19. So presumably the 2850 miles on the clock is not the total mileage the bike's done? I know you mentioned a new clock. What's the total mileage? Just curious as to the main bearing failure after what may be a relatively short life. Thanks.
     
  20. 18000 +/- miles however quite a few premature failures have been reported, some say due to mains being over shimmed, and even from the factory, apparently!
     
    • Agree Agree x 1
    • Thanks Thanks x 1
Do Not Sell My Personal Information