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Thread: need help with engine breather hose on 1971 R75/5

  1. #16
    Registered User AntonLargiader's Avatar
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    I'm sure BMW gave up on trying to describe the different breather system parts that were used in the '70s, but broadly the clamshell airbox systems shake out into 22mm single hose and 17mm dual hose. The P-shaped hose with the wax ring is a hybrid, where they're using a 17mm single hose in a system designed for 22mm single hose. The wax ring is only for that specific use: using a 17mm hose in a 22mm hole. And I think it is a recent thing that was added to the fiche; ten years ago when I was buying the P-shaped hose to replace the NLA straight hose I cut a section of the old hose and jammed the new one through it to fill the gap. I don't remember the wax ring being suggested at that time.

    I'm not sure if that P-shaped hose was ever used in production. The non-R65 engine housings changed to have the large breather chamber, and there was briefly a single hose for that system and then the square airbox came along with an entirely new setup. AFAIK the R65 first got dual hoses and then got a unique hose feeding the square airbox.

    I had a '78 in the shop with the dual 17mm holes and it needed a breather system. I probably should have bought the '77-only 11 15 1 265 039 hose and changed the right airbox cover to one with a 22mm hole, but I ended up fabricating a system using some later parts. It is a PITA that this is described so poorly in the fiche and that so many parts are NLA.
    Anton Largiader 72724
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    Virginia Motorrad Werkstatt BMW motorcycle service and repair in central Virginia

  2. #17
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    Thank You!

    I was wondering why there was a slot for the O'ring on the output sleeve on one side..
    and no channel for the other side... just the smooth output.

    crud.. ok... so one side of mine is non original
    I guess I'll look for a replacement side.

    thank you!
    brant

  3. #18
    Registered User AntonLargiader's Avatar
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    Or buy a vertical breather and use the P hose, which should fit nicely and will do a better job. But it's probably a lot more expensive that way.
    Anton Largiader 72724
    Tech articles - YouTube
    Virginia Motorrad Werkstatt BMW motorcycle service and repair in central Virginia

  4. #19
    #13338 PGlaves's Avatar
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    You might find a machine shop that can bore that 17mm opening out to 22 mm. From the photo it looks like there is room to do that.
    Paul Glaves - "Big Bend", Texas U.S.A
    "The greatest challenge to any thinker is stating the problem in a way that will allow a solution." - Bertrand Russell
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