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Full power one cylinder, weak on the other

Discussion in 'The Garage' started by vsop-dk, May 16, 2015.

  1. vsop-dk

    vsop-dk XS650 Addict

    Hi, hmm... about a couple of weeks ago, I noticed with my TM34-2 carbs, that the left hand plug were looking allmost as new, only with the tip a little bit colored.. The other plug looked as it should... I though maybe something had changed with the mixture, and got a hint from the forum it could might be weather changes etc.. So I changed the settings for the pilot jet and ran the bike for a time and plugs didnt change..

    I noticed in the same period that the camchain and the valves started pinging louder than usual.. So I adjusted the valves to specs and adjusted the cam aswell.. The bike is new build with only roughly 600km on the clock, so adjustments is needed.

    After above adjustments I ran some more and bike run great, but the plugs didnt change at all... so left hand plug looks allmost as new, even after several km driven.

    Today I changed the TM34-2 out with the Lectrons 34mm and im having a real hard time dialing in.. It used to be walk in the park for those carbs, but not this time, and I tested and tried again and again.. and ended up looking at the plugs, actually did that on off during the day while testing, and the left hand plug seems unused...

    The right hand exhaust is hot burning hot... while the left hand is only warm...

    It could be several things I guess, but I dont know exactly where to start off...

    - Pamco
    - Coil
    - Ignition timing (perhaps???)
    - Plug wires

    Im running a Pamco ignition, 277 rephased engine and exccel coil.

    Could definately need a helping hand :thumbsup:
    Last edited: May 16, 2015
  2. TwoManyXS1Bs

    TwoManyXS1Bs BBQ Hunter Top Contributor

    Hey, vsop-dk.
    It appears that you're up to speed with the usual suspects.
    So, all I can offer is the unusual:

    1 - A speck can get into an air-bleed jet and/or passage, and affect that jetting.

    2 - Did you notice any significant difference between left/right valve readjustments?
    (Thinking about potential subtle valve timing changes)...
  3. vsop-dk

    vsop-dk XS650 Addict

    TwoMany as usual, thanks for your response to my endeavours ;)

    There were no unusual in the valve adjustments, just slight adjustments and allso the same for the cam adjustment.

    The speck would be unusual for both the TM34 and the Lectrons..

    Im leaning to the coil or the pamco, just dont know yet how to troubleshoot that... Dont know either wether timing could cause that, but serioulsly dont think so.
  4. TwoManyXS1Bs

    TwoManyXS1Bs BBQ Hunter Top Contributor

    Ok, then continuing down the rabbit hole, or grasping at straws.

    Could degree wheel your cam, see if any lopsided timing irregularities.

    Slight loss of compression in one cylinder.

    Very slight/subtle oil ingress into one cylinder.

    PamcoPete has posted several times about the negative/positive polarity imbalance with single dual-output coils, leading to different spark energies with Iridium plugs, and the auto industry's adoption of different plug types to accomodate dual-output coils.

    With that in mind, could one of your coils be firing at opposite polarity to the other?
  5. vsop-dk

    vsop-dk XS650 Addict

    I could degree wheel the timing, but dont have that, I have a inductive timing light, that shows 36 degree btdc and thats fine as the petrol burns faster today than years ago..

    Compression tested to 200psi roughly on both cylinders just a couple of weeks ago.

    Oil engress in one of the cylinders can happen as its a new build engine, but the engine ran perfect up until a week or two ago.

    Im running a single dual output axccel coil 3 ohm should be top brand and had good reviews.. I use regular spark plugs not the iridium.
  6. TwoManyXS1Bs

    TwoManyXS1Bs BBQ Hunter Top Contributor

    Ok, that's the focus, then.

    Naptime here, we'll see if REM sleep cooks up anything...
  7. vsop-dk

    vsop-dk XS650 Addict

    Naptime here allso, nighty night ;)
  8. pamcopete

    pamcopete Ride.Enjoy.Life is Simple

    I guess I have never heard of running a dual output coil on a 277 conversion. I thought that there was an overlap on the valves that made that impossible. However, if that's what you are running, then all sorts of strange things could happen, most of which I know nothing about because you ain't supposed to do that. Are you sure it's not one of those Siamese coils that is actually two coils in the same housing?

    In any event, check the timing as late timing can cause an un burned mixture because it ignites with not enough time to burn completely before the piston has completed its stroke. Also, check continuity of the spark plug caps, and if you haven't done it already, new plugs.
  9. vsop-dk

    vsop-dk XS650 Addict

  10. pamcopete

    pamcopete Ride.Enjoy.Life is Simple


    Late means retarded. You can check for continuity by checking for 12 Volts at the spark plug cap with the engine not running but the ignition on.
  11. ippytattoo

    ippytattoo Just another grumpy hack.

    vsop bear with me here I hope I can describe this correctly. one thing you could do is swap the plug leads (leave the plug end connected and swap the 2 at the coil) and the 2 signal wires from the 2 pamco sensor plates (the outside wire connections on the dual coil) this will swap which coil fires which cylinder. You could also swap just the whole spark plug wires at the plugs and the coil to rule out a possible plug wire fault. that will help isolate whether it is after the pamco.
  12. vsop-dk

    vsop-dk XS650 Addict

    Yes ill test and advance the ignition some more, but its just been dialled in, could be wrong offcourse. Ill test and see.

    Yes, ill have to check the coil and plug leads and see wether the same behavior is the same on the other side. Thanks for the response.

  13. vsop-dk

    vsop-dk XS650 Addict

    I've tested the coil and it's working fine, I've tried reversing the Pamco to reversed side on the coil and it's same behavior on the left cylinder as before.

    Something causes the plug not to ignite.... And when the right cylinder exhaust gets hot the left hand is only hand warm.

    Both cylinders run, just only one of them runs as it should whereas the other only at 10 percent...
  14. vsop-dk

    vsop-dk XS650 Addict

    I Allso adjusted the timing to be a little more advanced...

    So new plugs, checked the plug cables and tested the coil and all is fine...

    What's there more to test? Should I order a new Pamco? Can that alone be ordered without all other bits and pieces?
  15. TwoManyXS1Bs

    TwoManyXS1Bs BBQ Hunter Top Contributor

    Thinking along the lines of "Ran fine, now acting up". It's not unusual for things to settle-in or vibrate loose shortly after a custom build, or just an overhaul. Might want to check and refresh all ground connections that involve bolts and large fasteners.

    Is this the ignition kit you're running?



    If so, you may want to closely inspect the sensor components and solder joints. See if anything loosened-up in there. Check the height of the sensors (small 3-pin components), their solder connections, and their spacing from the rotor backside...
  16. ippytattoo

    ippytattoo Just another grumpy hack.

    Just for the sake of testing and good measure you may want to re-torque the the head studs and retest your compression. Another test would be to use a spare spark plug and verify good spark on the weak side.

    I am not thinking this is an ignition problem with the Pamco.

    Another thing, have you tried using the enricher on the weak side? Also are you running 2 fuel taps? Are you sure they are both functioning? Have you verified fuel level in the bowls? Just throwing things at the wall here to see what sticks.
  17. vsop-dk

    vsop-dk XS650 Addict

    Hi, okay.. I've tested the sparks on both sides, they look okay but the only difference might be that the working side spark were straight and the troublesome side were jumping around, the spark were.

    I've checked, charged battery and reversed setup as suggested and coil works on both sides when testing, just not on the left hand side.

    The image shown with the Pamco yes looks similar, I'm using the setup for the rephased 277 with two magnets on the rotor.

    Allso I've disassembled the Pamco and inspected it as suggested and on the troublesome side there is solder missing on the negative wire as seen closeup on this image.


    Could might have something to do with it!???

    I've tested 10 sets of plugs and tried everything, the lectrons have clear fuel bowl and it's level... It works on both sides just the left hand side is only at 10% and exhaust never gets warm.
  18. TwoManyXS1Bs

    TwoManyXS1Bs BBQ Hunter Top Contributor


    If it was me, being on the other side of the world, I'd remove that sensor board and solder that black wire.

    But, this is PamcoPete's department.
    Strongly urge that you do NOTHING until he can comment on this...
  19. vsop-dk

    vsop-dk XS650 Addict

    I wont be touching anything... ;)

    Another question.. What would happen if I switched plug cables, reversed them as they are now... Just as a test!?

    Would I harm anything by doing so?
  20. pamcopete

    pamcopete Ride.Enjoy.Life is Simple


    Yes, just to save time, go ahead and solder the wire back, however, the PC board still gets a ground from the mounting screw. PM your address and I will send you a new plate on warranty.

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