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Running on one cylinder

Discussion in 'The Garage' started by Cribby, Nov 23, 2020.

  1. Cribby

    Cribby XS650 Addict

    So here we go again, asking for help

    Just spent a week recommissioning an XS1 that probably hasn’t run for many years

    I had it running a few months ago but it wasn’t firing on the left hand cylinder so I sent the carbs away for refurb to the same fella I always use (Motocarb in Liverpool). I stripped off the electronic ignition system as it was all in bits and refitted the original points based system. I spent a few hours timing all this up and setting the points gap, fitting new plugs and HT leads and I fitted a brand new loom

    She started on the third kick with choke but I still can’t get it to run on the left cylinder

    I have spark on both sides and if I squirt brake cleaner in to the left hand carb, it fires?

    I swapped out the left hand carb for another refurbished unit and still no fire

    HELP!!!

    Ant
     
  2. Cribby

    Cribby XS650 Addict

    Sorry, I meant to add a photo if that’s any good?

    40294062-F87F-4DDF-A7EB-135DA64B19D7.jpeg
     
  3. xjwmx

    xjwmx It's just the unknown. Top Contributor

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    You have a compression tester in that garage somewhere.
     
  4. Cribby

    Cribby XS650 Addict

    I do, think that could be it?
     
  5. xjwmx

    xjwmx It's just the unknown. Top Contributor

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    got gas, got spark, so makes sense
     
  6. Cribby

    Cribby XS650 Addict

    But if I squirt brake cleaner in the carb, it fires?
     
    GLJ likes this.
  7. GLJ

    GLJ Never go faster than your guardian angle can fly. Top Contributor

    Good point. I think I would check compression on both cylinders just to know what they are.
    Drop the drain plug on the left carb to check and make sure you are getting fuel into the float bowl.
    Also check for air leaks.
     
    Greyandridin likes this.
  8. Cribby

    Cribby XS650 Addict

    Good points, will do tomorrow
     
    Greyandridin likes this.
  9. thuban

    thuban Horse Scratcher XS650.com Supporter Top Contributor

    I don't know what kind of brake cleaner your using but if it's anything like starting fluid, it may hit on that but not on gas with poor compression. Key off throttle full open and kick it about 4 times on each cylinder and see.
    (Too late on the draw) :)
     
  10. Jan_P

    Jan_P XS650 Addict

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    Thinking out loud if compression tester does not give a clear answer
    First check ignition timing when running on the one cylinder,
    So it is close.
    Move the right hand coil + lead + plug to the left side
    Left side to right.
    Copper grease at all the right spots. Including ground.
    Check points gap and inspect so it appears right there.
    Measure voltage to points
    A little oil into the left Cylinder ( improving compression )
    Start outdoors because the oil will create smoke.
    If no start -- take out the plugs place them against the cylinder kick so the spark is there
    looking equal on both cylinders --- thereafter
    might be valves.
    Get back we will reevaluate
     
  11. Rasputin

    Rasputin XS650 Addict XS650.com Supporter Top Contributor

    Please check the crossover tube between the carbs that supplies the starter jet (choke) mixture.
    I think that early carbs have only got a choke on the LH carb.
    Please also ensure you have clearance in both rockers on the LH cylinder compression stroke at TDC.
     
    GLJ likes this.
  12. GLJ

    GLJ Never go faster than your guardian angle can fly. Top Contributor

    This a points bike. Don't think it run like that. Plugs will be firing at TDE.
    I could be wrong.
     
    Jan_P likes this.
  13. 5twins

    5twins XS650 Guru Top Contributor

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    It will if you switch the points connection wires too.
     
    Jan_P likes this.
  14. Jan_P

    Jan_P XS650 Addict

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    Thank you Lads
    I have not had points for fifteen twenty years. don't remember exactly
    how it was connected. The point !!! ---Was to move the parts you know are good to the side not firing
    See if one can move the problem
    Tanks again. Well get there as usual with some fine spirit of cooperation
     
  15. Cribby

    Cribby XS650 Addict

    Well, an interesting update!

    I had a day off working on bikes yesterday but plucked up the courage for a bit more fault finding today

    My mate turned up as I was opening the garage and I was explaining to him the mystery of the misfire

    To demonstrate what I was talking about, I put the bike and choke and it fired 2nd kick BUT it ran on both cylinders. And when I turned the choke off, the bike continued to run on both cylinders, albeit the left hand exhaust puffing a bit of black smoke when revved

    It actually ticked over!!!

    Logic, what logic?

    Ant
     
  16. Rasputin

    Rasputin XS650 Addict XS650.com Supporter Top Contributor

    Well, just goes to show what a day off does.
    Does it keep running?
     
  17. xjwmx

    xjwmx It's just the unknown. Top Contributor

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    I think there are several things happening, making diagnosing it confusing
     
  18. Cribby

    Cribby XS650 Addict

    Yes, more days off we need!

    yes it keeps running, though the tick over drops as the engine gets warm but I haven’t put the air filters on yet, that’s tomorrow’s job

    Ant
     
  19. Jan_P

    Jan_P XS650 Addict

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    Most likely the carburetors needed some " soaking "
    Nothing abnormal or strange
    Gas into the right places ..Float moving ..Membranes flexing
    Can be a little dust and so--- when things establish themselves it fires up
    And after a few miles and " Dynamic " up and down revving
    Fresh gas passing through it usually runs better
    Keep a look at the spark plugs if it runs uneven
    And be careful since the floats can get stuck and fuel dripping out.
    A gentle tapping on the outside with the handle of a screwdriver or hammer handle
    can get it moving again
    a Petcock is of course an advantage ,, be careful ..
    Perhaps remove the tank in the beginning if indoors and left for a day or more.
    Perhaps also the battery connection.
     
  20. 5twins

    5twins XS650 Guru Top Contributor

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    Puffing black smoke is a rich indicator. Slowly dropping idle as it sits there can be a slow leaking float needle and seat. The bowl slowly over-fills and chokes that cylinder out.
     
    Jan_P likes this.

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