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Crankcase Breather Kit

Discussion in 'Norton Motorcycles (Modern)' started by BritTwit, Jun 19, 2017.

  1. BritTwit

    BritTwit VIP MEMBER

    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


    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 VIP MEMBER

    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


    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


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


    Feb 24, 2014
    Sorry. Yes.
  7. gchoppin


    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 VIP MEMBER

    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


    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


    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
  11. richard-7


    Feb 24, 2014

  12. nopdog

    nopdog VIP MEMBER

    Apr 24, 2017
    Hi Richard
    Would it be possible to be copied in on that too.
  13. MxMartin


    Nov 13, 2017
    I last checked my catch bottle at about the 350mile mark and it looked to have about 1cm in it, I noticed tonight (650mile) that it looks to be about 1/3rd full (2+ cm) but can't tell if oil or oil/water mix.

    Question 1: would you have expected this to be emptied during a service?
    Question 2: is this about normal for the mileage for a Mk2 variant?

  14. Fast Eddie

    Fast Eddie VIP MEMBER

    Oct 4, 2013
    Q1: YES !!!

    Q2: Don’t know.
  15. BritTwit

    BritTwit VIP MEMBER

    Aug 25, 2009
    Question 1:
    Certainly I would expect the catch bottle to be emptied. The service people that have your bike’s specific configuration/history would know that it has the oil in airbox (OIA) fix kit. This would indicate hopefully that they should at least check for oil in the bottle, and inform you about its condition. This kit is after all a “fix” for a known condition that some 961’s have.

    Question 2:
    The OIA fix kit should prevent the situation completely. There should be no oil in the bottle. The bottle is just a safety catch to prevent oil from reaching your tires or disc rotor in the event that the fix does not work entirely. Perhaps during the initial run in, there will be more blowby from the piston rings and this could account for some oil being pushed to the bottle. However, I had the kit installed on my bike (2013 CR) at about 3000 miles. Since then I have only ridden approx. 300 miles with the kit, but have no oil in my catch bottle.

    I would call the service folks and inquire about this.
  16. MxMartin


    Nov 13, 2017
    Well it doesn't appear to have been emptied during the 1st service. If they did then my bottle is a third full in 75 miles which is worrying. I have to talk to Norton tomorrow so I will mention it.
  17. TonyA


    Jan 16, 2015

    Servicing of Bottle:

     The bottle will allow for approximately 3000 miles of riding before it fills (under normal conditions).

     It is recommended that the bottle is checked every 500-1000 miles, to ensure that it will not overfill. Note: If the bottle overfills, there is a risk that the oil will spill onto the rear tyre. This will reduce rear tyre grip dramatically, which could result in an accident.

    If the oil is not allowed to drain into the bottle due to overfilling, the oil in the airbox could potentially be sucked into the engine, resulting in the motorcycle running poorly and reducing performance.

    1. If the overflow bottle is filling too quickly, potential causes are:

     Oil level too high.

     Oil filling method incorrect.

     Compression too low – increases crankcase pressure and forces oil into airbox.

     Oil pipes crushed or kinked somewhere, restricting oil flow.

     Incorrect grade of oil being used.

     Faulty operation of one way valve in oil pump.

     Weak scavenge/faulty oil pump.

    If necessary, take the motorcycle to a professional Norton technician to check
    BLIGHTYBRIT/SF likes this.


    Feb 28, 2016
    I think Tony A is spot on ,Mine gets about half full in 3000 Miles,tends to drip more I think at higher revs,but pretty accurate reply from all I been told by by everyone
  19. Kiwi961


    Nov 22, 2016
    I’ve done about 1700 miles in the last year and never emptied it- there is only about 2mm in there. I guess I’m just lucky
  20. pingu-nz


    Jun 24, 2011

    Not all the oil in airbox fixes work .

    This was installed by myself to see when the oil puked from the crank breather after factory fix was installed.
    I had a camera setup while riding and it only puked oil at a idle on side stand after about 30 seconds.

    Now I have disconnected the airbox from the breather and have a catch bottle mounted on the swing arm, I have also reinstalled the rocker cover banjo bolts.


    I also have installed a oil tank breather tube on the filler cap to relieve the pressure in the oil tank. this is also plumbed into the crank breather.

    Nice and simple
    Drain oil from catchbottle after each ride or during.
    Monitor the amount of oil drained to replace fresh in oil tank.
    No oil going into airbox ,engine runs much crisper .
    Euro compliant hell no!!
    Is my bike going to destroy the world with pollution ? Probably :)
    Why do these bikes have a 6mm breather hole for the crank ??
    And the fix is to block off the rocker cover Banjo bolts ???
    Would i sell my Norton ? Hell NO !!!
    contours likes this.

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