a barn fresh r50/5

Discussion in 'Airheads' started by bmwblake, Mar 26, 2012.

  1. chasbmw

    chasbmw Long timer

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    Just to remind you that not any airhead camshaft will fit, it will be a small front seal cam with a woodruffe key at the oil pump end, you will have to remove gearbox and flywheel to fit (I think). Motoren Israel sell a wide range of camshafts including small front seal cams. If you are buying second hand try to buy from someone who knows what you need.

    Charles
    #61
  2. bmwblake

    bmwblake upside down parker

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    Let's say I have access to a cam from an r75 or an r90. Do either of those meet this spec?


    #62
  3. wirewrkr

    wirewrkr the thread-killer

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    it depends on the year of the engine. You need the cam from a 1970-75.
    #63
  4. bmwblake

    bmwblake upside down parker

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    That means I have 2 to choose from. Thanks to everyone for sharing the info. I've been around airheads a good bit but never to the cam.


    #64
  5. bmwblake

    bmwblake upside down parker

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    it's handy to have an extra block around with a cam you need in it. i'm noticing that there's a hammer around in a lot of these pictures. i have no idea what i was doing with it. must've been providing comfort of some sort.

    [​IMG]

    and then on to the motor i care about.

    [​IMG]

    and then:
    [​IMG]


    and out comes the r50 cam:
    [​IMG]


    the cam that came out of the r75 block was rather nasty. i scrubbed it and then cleaned it.

    r75 cam in the rear, r50 cam in the front:
    [​IMG]
    #65
  6. Lornce

    Lornce Lost In Place

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    This is a good thread, bmwblake. I like that the various stages of assembly/disassembly are well photo-documented.

    :thumb

    Robert, Not sure I knew about this before. What's the difference in the 308 camshafts between '70-'75 and '76-'78?

    :scratch
    #66
  7. datchew

    datchew Don't buy from Brad

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    :lurk

    Hammers = good. But i think you're low on beer... just going by the pics and all. :lol3
    #67
  8. disston

    disston ShadeTreeExpert

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    I think the Woodruff Keyed cam shafts also have two different sized Keys. Matches the oil pump rotor so you can use either one as long as it matches the oil pump rotor.
    #68
  9. Bill Harris

    Bill Harris Confirmed Curmudgeon

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    How is the bearing flange on the front of the R75 camshaft? How is the sprocket? This is the time to change them out (picky job, you need a press).
    How is the wear in the cam lobes? That eccentric pattern on the nose is OK, but pitting is a concern.

    When the cam is installed in the block, check the runout on the ignition advance unit shaft ("nose")-- it sometimes gets bumped and off. Fix is measuring the runout with a dial indicator and tapping the nose with a hammer til it runs true.

    Looking good, otherwise.
    #69
  10. wirewrkr

    wirewrkr the thread-killer

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    2 things, #1 is the woodruff key (oil pump drive) is bigger on the 76-78 and #2 is the cam seal area, which is much bigger in diameter
    #70
  11. bmwblake

    bmwblake upside down parker

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    I've got the cam back in and made sure the oil pump was squared away with the woodruff key fitting correctly.

    Question for you guys. My alternator rotor from the /5 is in rough condition. I have a spare rotor and stator from an 88 r100 and a stator from a /6. Will either of those combos work?
    #71
  12. chasbmw

    chasbmw Long timer

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    Your bike has a 105mm diameter stator, this changed to a larger diameter in the 75 model year( I think) so the 1988 parts won't fit, the /6 part might fit.

    The 450w alternator made by emerald isle and sold by Rick in the US is made in a 105mm variant, it's what I have on my mid 75 R90/6.
    #72
  13. bmwblake

    bmwblake upside down parker

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    I know the stator and rotor differ in size. The question is whether there is an issue mounting a match later model stator and rotor to the /5.
    #73
  14. chasbmw

    chasbmw Long timer

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    It's obvious really, the timing cover is machined to accept the right sized Stator, so if you want to fit a later stator then you have to fit a later timing cover, but if you do that then you have to change the camshaft as the earlier camshafts have a smaller seal and doubtless there are other differences that I don't know of. Looking at the Motobins site it looks as if the rotors are the same.
    #74
  15. datchew

    datchew Don't buy from Brad

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    have you fitted the newer charging bits against the existing timing cover to see if they'll mate up?

    I have a 90's charging system on my /2, but the timing cover had to have an adapter ring to allow them to work. Might be something already known out there for /5's.
    #75
  16. bmwblake

    bmwblake upside down parker

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    Forgive the lack of pictures. I have the parts I need for the charging system. I still need to get the charging bits back on the motor.

    Last night was spent scraping several layers of bad paint from a front fender. The rear fender is alright but the front needed attention beyond sanding.

    I'm still waiting to get my frame and other big metal bits back from paint.
    #76
  17. bmwblake

    bmwblake upside down parker

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    long time no update. things should get more interesting now.

    [​IMG]
    #77
  18. backdrifter

    backdrifter Wannabe rider

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    Lookin' great, Blake! That's right about the time I felt my project became really fun. All the old stuff has been torn apart and you start the process of making it look new again. It's very gratifying! Congrats, and keep up the good work!
    #78
  19. bmwblake

    bmwblake upside down parker

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    progress is being made, i've just been slack on updating this thread.

    i've moved into a shared garage space. it was a great excuse to clean up the garage and reorganize.

    frame bits back from paint and the engine on the floor:
    [​IMG]


    steering head bearings in, swingarm, final drive, and subframe mounted:
    [​IMG]

    engine in frame, driveshaft connected, driveshaft boot wrestled on, footpegs mounted, bars on loosely so that i could sit on it and make vroom noises.
    [​IMG]


    exhaust headers on, voltage regulator on:
    [​IMG]
    #79
  20. bpeckm

    bpeckm Grin!

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    That's a rather nice "shared" space! I bet it's good to chat with others and have that moral support....:evil

    ...........and to help you lift it down, all in one piece.......


    looking good!!
    #80