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Weird spark on right side cylinder

Discussion in 'The Garage' started by GavTX650a, Jul 31, 2020 at 8:59 AM.

  1. GavTX650a

    GavTX650a XS650 Member

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    Ok so...

    With the plug wire on the right side hooked up cylinder doesn’t fire if I HOLD the plug wire just off the plug it arks and fires the cylinder!

    so plug on dead cylinder
    Plug wire just held off the plug it fires!
    I’m lost on this one!
     
  2. Jan_P

    Jan_P XS650 Enthusiast

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    I m also lost not knowing what bike or ignition system but if this was me
    I would shift the spark plugs over left plug to the right side and right to the left side
    see what happens to start with.
    Depending on what ignition system -then shift the cables over.
    Boyer ignitions has a " Waste Spark " system so it fires both cylinders even though only one Cylinder is in the correct firing position
    So if so a shift of the caps ( with cable ) directly can give info.
    Maybe a defect cap. ???
     
    Paul Sutton likes this.
  3. GavTX650a

    GavTX650a XS650 Member

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  4. GavTX650a

    GavTX650a XS650 Member

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    Sorry... 74 TX650A
    The bike has points
     
  5. Jan_P

    Jan_P XS650 Enthusiast

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    Thank you
    With Points I would do like this.
    I am not exactly sure about 1974 but on my 1980
    Stock there are 2 Coils under the thank ..where the cable goes out to the spark plug caps.
    I would put the spark plug caps on both
    Please inspect that the one with problems looks OK at the Bottom .No dirt or so .
    I use a bit of Copper grease to ensure that there are contact.
    And that the cap is screwed on the cable properly..
    And check that the connection at the top of the spark Plug is OK not loose
    Then I would take the cable and Plug ( going from the coil) on the right side and move to the left side
    And the cable on the left side with spark plug to the Right side..
    Trying to start again .
    At this point in time I Suspect a defect spark Plug cap.Or bad connection.
    In that case the problem is now at the left side.
    If so make the same test as in the first place.
    After that test I would move over the right side spark Plug to the left side and the left to right.
    Please try this then we reevaluate Paying attention to the spark plug cap status that are perhaps old cracked or so
    If you have a spare spark plug cap One way forward is to put it on directly and test.
    Or can get one or two close By
    Not moving anything else.
    Please report success or failure or what else happens
     
  6. GavTX650a

    GavTX650a XS650 Member

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    I’ve changed coils plugs plug wires caps on both ends I switched everything to other sides still just right side!

    I have a XS PMA with capacitor
     
  7. Jan_P

    Jan_P XS650 Enthusiast

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    Ok Ok ..
    As I understand it XS PMA is a charging unit
    And no battery ..is in the machine . spark inspection is not possible at points

    Now I looked it up in a Haynes manual
    There are one more part that needs attention the Capacitor. ( Condenser ) To the points
    Again mine is an 1980 but when I look at the one I had in there , many years ago there are two leads coming out of the
    Capacitor.
    And According to the schematic those goes to each point.
    I would switch those so the one now going to right vill go to left.and vice versa

    it says
    The two condensers are clamped to the head steady plate and are wired individually to each set of points
    The screws that hold the condencers to the plate also form the earth connection and should be checked for tightness

    Capacitors do age a wellknown fact at least in HiFi equipment
    Again please report progress
     
  8. GavTX650a

    GavTX650a XS650 Member

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    Hi again
    I really appreciate you helping me!

    I’ve done this step already...switching of the condensers and put a new capacitor in as well!
     
  9. Jan_P

    Jan_P XS650 Enthusiast

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    Ok Ok we all have been there standing -- at the roadside. cars Roaring by ,,With the behind up in the air.
    trying to figure out if the match down the tank is the best solution.
    Not seldom in black letter gear in over 30 Celsius
    So to sum it up
    Everything is new.. What about the points. Are they new ? Inspected. ?
    If they also are new please sum it up in a list what action is done . What actions been taken.
    What is new and what is not.
    If spark plug is in the cap and the plug is resting against the block ..not inserted in the cylinder.
    No spark then either ???
     
  10. GavTX650a

    GavTX650a XS650 Member

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    Hi again!

    everything is new except
    points ..I haven’t looked them yet

    the spark plug sparks outside the block but not in it!

    so when I put the plug in the cap and put it up against the block I get spark once plug is inside the block I get nothing
     
  11. Jan_P

    Jan_P XS650 Enthusiast

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    Aha Mr Sherlock Holmes .. ,, How do we know that there are no spark inside. ?
    Usually there are .So it might not be a Ignition fault at all.
    If compression is Ok Carburetor .??
    One way to test might be Start gas into the cylinder or intake.
    Via the spark plug hole.
    Motor starter .. You did not hear that from me Those chemicals are not always good.
    Perhaps gasoline is better.
    But now I ( for a while ) do not believe it is a Ignition problem. At all.
    Provided the timing is not off, Totally.
    Did this happen suddenly on a running bike. ?
    Need to think how that is done without battery and no starter engine.

    I have never seen that ,A spark outside and no spark inside .Especially with new parts.
    Does the bike run on one cylinder at all. Showing signs of life.
    Any ignition at all. Kickback on kick or strange sounds ? Shooting in exhaust ??
    If it runs take a look at how it looks on the non running cylinder at the points.
    Sparks and so.
    Strobe light near ??
    Point gap check would be the first thing to do.
    Please report
     
    SomervilleXS650 likes this.
  12. SomervilleXS650

    SomervilleXS650 XS650 Enthusiast XS650.com Supporter

    Yes, to Jan's question..... how are you determining that you are not getting spark when the plug is installed?
     
  13. grizld1

    grizld1 Grumpy old man Top Contributor

    There will still be spark with the cap installed.When you hold the cap away from the plug you increase resistance and boost voltage to the plug. The stronger spark can cause a cylinder that won't otherwise fire because it's down on compression, getting an otherwise unusable air/fuel mixture, or has a fouled plug to light up. Add valve lash to the inspection list.
     
  14. bikefreakjon

    bikefreakjon XS650 Enthusiast

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    Sometimes a weak spark will get stronger when you unplug the coil wire but hold it near oh, I'm not exactly sure why it does that.

    Bad plug, bad cap, bad wire or coil.

    Or I'm not really sure if this has been answered but if you have points they're going to be suspect!
     
    grizld1 likes this.
  15. GavTX650a

    GavTX650a XS650 Member

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    Hi

    the right side kicks in and out like you said when plug is in the block! Left side runs when right wire is off but right side will not run when I pull the left side wire off!

    I was just riding and it just started all of a sudden!

    when I throttle up it kicks in and out like I have power than I don’t
     
  16. Jan_P

    Jan_P XS650 Enthusiast

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    Ok Ok this was actually a tricky one
    I notice that experienced gentlemen are joining.
    I have had problems with charging for 35 years more or less.
    So those parts I Know more about and when it comes to carburetors mr grizid1 and others are the Guru on the
    hill.more than myself. As it seems.

    So that described with going out on throttle up. Can happen if the charging and / or battery is weak
    The charging voltage I Measure Plain and Simple with a Voltmeter across the battery which I now recall you dont have sorry about that ,this is an edit
    Engine on
    It should be around 14 volts. Lights on if to low other inspections are needed.

    Then I would try to get hold of a strobe lamp. in this case I do not know availability in Canada or here
    nowadays.
    But a cheap one did not cost much last time i bought one $ 10 -15 or so flea markets have them
    sometimes. Perhaps a friend can lend you one. I have used them many times over the years.
    Quick and easy to use .. Since bike runs on one cylinder it will work check on both.
    That strobe light can also give info if you have spark all the time on the right cylinder.
    So the ignition is spot on.

    If I should guess you have it .( spark ) .or get it after point service when Voltage is up.
    So far this are simple needed service, . BUT

    Although I am no expert I have had that problem with dirt in the Carburetor that also can make a Cylinder go out.
    As I understand it mostly Pilot Jet and Idle circuit. Also happened out of the blue one summer night -- but in my view the above charging and Ignition is first
    needed and simpler. To do.
    And go for the other aspects when these are checked and OK

    I would also replace the right side Point. And set them both I do not remember the Procedure .but I can look it up if you don't have it somewhere. After the above checks are done.
    It is difficult to be certain they are OK and no partial short circuit + regarded a regular service.
    But as it seems you have it under control and buy new so i suppose this was already on the list.
    Please give info .. With luck carburetor and valves can wait.
     
    Last edited: Jul 31, 2020 at 4:54 PM
  17. GavTX650a

    GavTX650a XS650 Member

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    Update! I decided to go with electric ignition I inspected the points and lobe and both are damaged! I’ve rebuilt carbs and I’ll give a update when I install the new ignition system
     
    Boog likes this.
  18. Jan_P

    Jan_P XS650 Enthusiast

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    All right ..Progress Now we are getting Somewhere You seems to be a man who is..
    Doing a proper job
    Some electronic ignitions require a battery and are sensitive for that Boyer Bransden fex.
    So that is an aspect. .. to take into consideration
    Perhaps worth mention --- A compression test can give info as regards to that Right Cylinder.
    BUT At this point in time we believe the Points ..are the cause. Seldom two faults at the same time .
    When it comes to Machinery.
     
    Boog likes this.
  19. GavTX650a

    GavTX650a XS650 Member

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    Well when it comes to me if I didn’t have bad luck I would have no luck!

    I did a compression test (cold) and go 125 each side that’s a bit low? Or normal for a cold test?
    Thx again
     
  20. bikefreakjon

    bikefreakjon XS650 Enthusiast

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    Did you hold the throttle wide open?

    That can make 20-30# of difference in the test
     

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