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1975 Norton Mk3 distinguishing features

Discussion in 'Norton Commando Motorcycles (Classic)' started by p400, Feb 2, 2019.

  1. L.A.B.

    L.A.B. Moderator VIP MEMBER

    Joined:
    Nov 20, 2004

    pdf page 8:

    [​IMG]


    The section F bush dimensions aren't correct. The Mk3 shock lower bush is Edit: 0.942" wide.
     
    Last edited: Mar 3, 2019
    p400 likes this.
  2. dynodave

    dynodave

    Joined:
    May 28, 2003
    The little bit of crap/grit that tries to pass by the piston, on it's way to the exit hole marked in red, will also dig into the aluminum and score it a bit.
    Cleaning and buffing off/crocus cloth the piston is good... but unless you also remove the aluminum scratches you will never restore a slick surface and it never works as well as it should. It is a bit of an inspection and maintenance item if you want it to work reliably.
     
    p400 likes this.
  3. p400

    p400 VIP MEMBER

    Joined:
    Jul 14, 2014
    Were the front and rear brake rotors chrome plated when original?

    FrontRotorChrome.jpg
     
    Last edited: Mar 3, 2019
  4. Ron L

    Ron L VIP MEMBER

    Joined:
    Feb 27, 2004
    Yes, but not for long! :(
     
  5. Jerry Doe

    Jerry Doe Admin

    Joined:
    May 21, 2003
    The crank cases are stronger on a mk3 around where the main bearings go in
     
  6. Ron L

    Ron L VIP MEMBER

    Joined:
    Feb 27, 2004
    Several differences in crankcases.
     
  7. p400

    p400 VIP MEMBER

    Joined:
    Jul 14, 2014
    What supplier sells the best stock exhaust system for a MK3?
    Pipes, mufflers, crossover, clamps , gaskets, flange nuts, etc.

    Not looking for performance upgrade, not looking for more sound.......looking for quality components.

    if it is a common manufacturer/supplier, looking for best price from vendor.

    Advice welcome .
    Thank you


    1975MklllInterstate.jpg
     
  8. L.A.B.

    L.A.B. Moderator VIP MEMBER

    Joined:
    Nov 20, 2004
    Original 'black cap"/"bean can' silencers/mufflers or (more popular) 'peashooters'?

    Peashooters use a different set of mounting plates.
     
  9. Bob Z.

    Bob Z.

    Joined:
    Mar 30, 2012
    View attachment 8836

    Part 36 circlip on the rear shocks diagram; for the Mark 3 rear wheel change the brake caliper bracket needs to be loosened for removal by loosening the lower right shock bolt nut. The circlip would help to limit backing off the nut.

    Removing and re-installing the Mark 3 rear wheel is almost a 2-man job.
     
  10. p400

    p400 VIP MEMBER

    Joined:
    Jul 14, 2014
    black cap bean can seems the best, but it would be nice to know who sells the best of either.
    Thank you
     
  11. worntorn

    worntorn

    Joined:
    Dec 22, 2006
    If replacement Black Caps are the same as the originals then these will give you a very quiet bike with a power-sapped top end.

    Glen
     
  12. 850cmndo

    850cmndo

    Joined:
    Dec 9, 2009

    Certainly stronger than early MKI's. Don't ask me how I know.
     
    Last edited by a moderator: Mar 5, 2019

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