BMW K75 Engine Refresh

Discussion in 'Old's Cool' started by wmax351, May 13, 2013.

  1. wmax351

    wmax351 Been here awhile

    Joined:
    Mar 13, 2011
    Oddometer:
    743
    Location:
    Marin County and Berkeley, CA
    Browsing Craigslist, and found a low miles '95 K75 engine for 70 bucks, less the water pump, fuel injectors, with the clutch. I'm going to put it on my bike, when I am replacing the clutch, as my 100k engine is getting a bit tired (uses a good amount of oil, blowby, shitty mileage, etc). Leaks in a few places too. Think there may have been poor maintenance in its past.

    However, before I put it in, I will go through the engine to make sure it is fresh, break the glaze on the cylinders to make sure I can seat the rings/break-in as I would like, reseal, check clearances, etc.

    Any thoughts?

    I am trying to decide how to clean it. I am thinking plug up the ports, tape over the open oil pan, and hit it with a pressure washer and soap before tearing it down. That way I can start with it somewhat clean.

    For breaking the glaze, it has nikasil bores, so I will scotchbrite and soap it. If need be, I will track down a ball hone.

    Once it is opened up, I think I will set up a diy spray booth for the pressure washer, and use that on all the aluminium parts.

    With the head, should I lap the valves? I will be replacing the valve stem seals.
    #1
  2. bmwrench

    bmwrench Long timer

    Joined:
    Nov 10, 2006
    Oddometer:
    2,424
    If you are going to reuse the head, you should cut or regrind the valves and seats. Lapping valves and seats that have not been machined is a waste of time.

    The next question is whether the parts are in good enough condition to reuse.
    #2
  3. H96669

    H96669 A proud pragmatist.

    Joined:
    Nov 20, 2009
    Oddometer:
    4,748
    Location:
    Hiding off Hwy 6, B.C.
    Low miles....may not need much more than a leak down test, camshaft inspection, valve adjustment and maybe an internal inspection with a borescope altough you can see a lot of the bore from the crankshaft side.
    #3
  4. wmax351

    wmax351 Been here awhile

    Joined:
    Mar 13, 2011
    Oddometer:
    743
    Location:
    Marin County and Berkeley, CA
    Its a low mileage engine. I forgot what the guy said exactly, runs in my mind it was in the 30k's at most.

    My main goal is to do the break in right (hard) and start out with a good leak-free engine.
    #4
  5. bmwrench

    bmwrench Long timer

    Joined:
    Nov 10, 2006
    Oddometer:
    2,424
    I misunderstood-I thought you were going to rebuild the head from your original motor.
    #5