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73' Norton Mark I Running Rough

Discussion in 'Norton Commando Motorcycles (Classic)' started by Eric Bauer, Jan 26, 2020.

  1. kommando

    kommando

    Joined:
    May 7, 2005
    Stepped spray tubes, main jets are as normal.

    [​IMG]
     
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  2. Eric Bauer

    Eric Bauer

    Joined:
    Jan 10, 2020

    And MexicoMike in for the win!! Looked at the balance hose and it had completely come off the left carb. Pushed it back down and back in business....wow all that for that, ha. Thank you all for your help!!!! So no clamps on those or anything?
     
    Craig, 998cc and Tornado like this.
  3. MexicoMike

    MexicoMike

    Joined:
    Jan 31, 2010
    Hey! Glad it worked out to be something simple AND free!!! The Norton parts diagram does not show clamps for that application and I have never used them but it certainly wouldn't hurt if you decided you wanted them!
     
  4. Tornado

    Tornado VIP MEMBER

    Joined:
    Dec 5, 2017
    But, that should in principle affect both sides from running correctly...as air can now enter both manifolds.
     
  5. Eric Bauer

    Eric Bauer

    Joined:
    Jan 10, 2020
    Correct - I had tweaked the carbs trying to fix it and put them both back to their original settings which I left out
     
  6. Tornado

    Tornado VIP MEMBER

    Joined:
    Dec 5, 2017
    So maybe you had tried to compensate bad idle by carb tweaking before discovering air leak. Getting one side out of balance to other. Makes more sense.
     
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  7. Eric Bauer

    Eric Bauer

    Joined:
    Jan 10, 2020
    thats correct, exactly what I did. Although to your point it is weird that one side was effected so much more than the other. Any thoughts? Also weird it just popped off - I need to read up on what it does.
     
    Last edited: Jan 26, 2020
  8. MichaelB

    MichaelB VIP MEMBER

    Joined:
    Jan 14, 2004
    I like simple solutions.
    However, I agree that opened a vacuum leak to Both Sides. Both should be affected.
    I use a small zip tie as a clamp.
     
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  9. lazyeye6

    lazyeye6 VIP MEMBER

    Joined:
    Feb 28, 2014
    I had it happen in my early days of ownership. Back when I had a Boyer Ignition. As I recall, I had experienced
    occasional kick-back, probably meaning the timing was not optimally set. A back fire will easily blow one of
    the balance tubes off of it's spigot. No problems since installing a Tri-Spark ignition. I have not needed to ever
    use clamps on the balance tube.
     
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  10. Eric Bauer

    Eric Bauer

    Joined:
    Jan 10, 2020
    Do you guys have know the best size and / or material for the balance hose? This one keeps popping off and one side is just really loose - I could clamp it but it just seems like it's worn out - not experiencing any kickback but it still pops off from time to time. Last night it flew off after a strong kick.
     
  11. maylar

    maylar VIP MEMBER

    Joined:
    May 13, 2007
    Standard automotive vacuum hose - I think it's 1/4".
     
    Last edited: Feb 14, 2020
  12. Eric Bauer

    Eric Bauer

    Joined:
    Jan 10, 2020
    Thank you - it's started running lean again / weird again so will try to just replace this first perhaps it has cracks.
     
  13. Tornado

    Tornado VIP MEMBER

    Joined:
    Dec 5, 2017
    I just grabbed some 1/4" windshield washer hose I had kicking about in a drawer and it is a good snug fit.
     
  14. MichaelB

    MichaelB VIP MEMBER

    Joined:
    Jan 14, 2004
    Can’t remember ever having one come loose or fall off, ever.
     
  15. maylar

    maylar VIP MEMBER

    Joined:
    May 13, 2007
    I had one dry out and crack and break off from one end. Easy diagnosis, instant high idle.
     
  16. Bernhard

    Bernhard

    Joined:
    Apr 20, 2011
    4 strokes suck, bang blow, I think there's an irony in there, somewhere . . . . .
     
  17. Eric Bauer

    Eric Bauer

    Joined:
    Jan 10, 2020
    It had a crack in it upon further inspection so we shall see of changing it works...praying to motorcycle gods.
     

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