Crankcase Breather Kit

Discussion in 'Norton Commando 961 Motorcycles' started by BritTwit, Jun 19, 2017.

  1. BritTwit

    BritTwit

    Joined:
    Aug 25, 2009
    That is the most bizarre thing I've ever heard.
    I can't see how oil would start draining from the airbox after the engine is shut off.

    Unless the oil light was on because all of the oil was in the sump, and was already being pushed into the airbox before the motor was shutdown.
    Then you just witnessed the remainder of the airbox oil draining into the bottle.

    Anyway you look at it, very strange indeed.
     
  2. Fultonrn

    Fultonrn

    Joined:
    Dec 22, 2015
    Had exactly the same problems with a me 2 2016 which was returned to dealer under warranty.
    They did the warranty work ,started the engine , oil filled plastic catch bottle in seconds / minutes and kept coming out rapidly. They stopped bike and reputedly asked factory for advice. Where advised to replace check valve in oil line from pump to oil cooler with a new one that factory would supply as there had been faulty valve and factory had a different new replacement valve.
    Valve was supplied, fitted and dealer reportedly did a 30 + mile test run without problem.
    Dealer confirmed valve replaced by photographic evidence and stated he tested valve when removed and it did flow in both directions. I'd it was not working as a non return valve.
    I am not aware of oil levels as dealer warranty work involved oil drain and replacement.
     
  3. BritTwit

    BritTwit

    Joined:
    Aug 25, 2009
    It is 50 degrees (F) this morning in NYC.
    Like Spring in January.

    Started my 961 this morning and let her idle for a while after an 11 week slumber following battery replacement.
    There was no oil deposited in the catch bottle which is a good sign and indicates oil is no longer migrating from the oil tank to the crankcase while sitting for long periods.
    So appears that the oil in airbox fix is doing its job properly.

    Now if it would just stop raining so I could thrash it about on the road.
     
    contours likes this.
  4. richard-7

    richard-7

    Joined:
    Feb 24, 2014
    We feel a huge part of the issue has to do with the rings and alignment of the rings and how they pressurize the bottom end. Then of course the head needs drilling so the oil can escape back down. Anyhow, too much to type.
     
    contours likes this.
  5. Raphi

    Raphi

    Joined:
    Aug 17, 2015
    Do you mean the piston rings?
     
  6. richard-7

    richard-7

    Joined:
    Feb 24, 2014
    Sorry. Yes.
     
  7. gchoppin

    gchoppin

    Joined:
    Sep 26, 2017
    My '14 sport pushes very little oil into the air box. A drop or two when I pull the plug. Did I just get lucky with my motor? I keep the oil on the full line.
     
    contours likes this.
  8. BritTwit

    BritTwit

    Joined:
    Aug 25, 2009
    Does your bike have the new longer dipstick?
    If so, that will help prevent you from overfilling the oil, which is one of the causes for oil in the airbox.

    My issue was oil migrating to the sump over time when sitting for a long time.
    Then being blown up the breather into the airbox when the engine was started.
    If you are not experiencing this then I would say you are lucky.
    The kit that was installed on my '13 model included a one way valve pressed into the oil pump housing to restrict back flow to the engine.
    It may be that newer MKII Nortons have this valve built into the oil pumps now.
     
  9. richard-7

    richard-7

    Joined:
    Feb 24, 2014
    They’re all hand built so It depends on the assembler for the most part and then also the tolerance stack up of the components. Sounds like you have a good build.
     
    gchoppin likes this.
  10. bushman

    bushman

    Joined:
    Jan 27, 2015
    Since I have head still on the bench, should I consider doing some drilling? Can you direct where and how please>
    Thanks Richard
    JIM
     
  11. richard-7

    richard-7

    Joined:
    Feb 24, 2014

    Ok
     
  12. nopdog

    nopdog

    Joined:
    Apr 24, 2017
    Hi Richard
    Would it be possible to be copied in on that too.
    Thanks
    Simon
     

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