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The black and white wire tci fj600/Xj600 1985

Discussion in 'XJ Technical Chat' started by mark1911, Nov 20, 2020.

  1. mark1911

    mark1911 Member

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    Having a problem trying to get a spark on my Fj600 85. The bike cranks but can't get a spark on any of the plugs. I read about the black and white wire on here so unplugged mine from my tci and now there's a spark on all 4 plugs only briefly and the bike sort of stutters and cuts out. Is this a ground issue with the side stand or one of the safety switches I think my neutral switch is faulty. I also read it could be a problem with the tci potentially am I correct or is it something else like the pickup coils or ignition coils themselves?
     
  2. XJ550H

    XJ550H Well-Known Member Premium Member

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    that wire is how the safety switches kill the motor by ground out the tci. should rum with it disconnected.
     
    Last edited: Nov 21, 2020
  3. mark1911

    mark1911 Member

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    OK so I can completely disconnect this wire and leave it out the block? We're does it run back to and is the neutral switch causing the fault as I have it earthed to the case at the minute and the lights on?
     
  4. XJ550H

    XJ550H Well-Known Member Premium Member

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    it connects to the clutch safety switch and side stand relay. you can disconnect it as that is equal to removing the sidestand relay.
    when in gear and sidestand is deployed it grounds out the tci to cut the moter. or if yu put bike in gear with sidestand down it stalls bike.
    the neutral switch is part of the clutch safety switch it is used to prevent bike from starting when in gear and clutch lever is not pulled in.


    un earth (ground) the neutral switch wire and see if bike will start and run with clutch lever pulled in that will tell you if the neutral is affecting the bike. I doubt it is an issue or your bike would stall when shifting from 1st to 2ed when properly installed.

    I do not have a wiring diagram for your bike on hand, so it I am going on what i know of the other bikes.

    so have you ohmed out the pickup coils and ignition coils to see if they are in spec?

    I am suspecting a faulty tci at this point or bad wiring in the safety circuits
     
  5. mark1911

    mark1911 Member

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    Hi I did as you suggested and completely removed the black and white wire and it sparks now on all 4 pots. At the moment I have the clutch switch by passed just by twisting the 2 wires together should i leave them disconnected and try and start the bike. I also unearthed the neutral switch ie removed it from the crankcase and it still turned over and cranked. Used a multimeter on the pick up coils and found when I unplugged the black orange and grey, I got 114 ohms going from black and orange and black to grey Haynes states 108 to 132 ohms, but I know they have 2 be tested at temperature 20 degrees celsius 68 degrees farineheit. So ran a hair dryer over them and the range didn't change at all really went slightly up if anything but didn't bounce around unsure if this is correct though. No I haven't checked for resistance on the ignition coils yet.
     
  6. XJ550H

    XJ550H Well-Known Member Premium Member

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    with the clutch switch twisted to gether bike will start in gear without clutch pulled in (be careful) if you untwist those wires the bike will only start in neutral.
    so you need to keep it twisted together untill you fix the neutral switch.

    if its firing now does it stay running?
    look at other possible causes dont get focused on the spark.
    could be bad plug caps, bad/fouled plugs. fuel supply
    also check charging system if it is putting out low voltage that can cause spark failure

    remember motorcycles are a collection of systems that work together to make motor run.
     
  7. mark1911

    mark1911 Member

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    OK at the moment am in the middle of cleaning out the fuel tank I'll put it back on add some fuel and see if it fires. But for the time being am I OK to leave the black and white wire off the bike? Just how do you test if the charging system works? I believe it has to be running with the wire unplugged on the loom side and probed with a multimeter correct? What am I looking for specifically drop in voltage to the battery etc.
     
  8. XJ550H

    XJ550H Well-Known Member Premium Member

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    you cam ohm out the components , rotor and stator to see if it is in spec. open the alt.cover check brush length and that copper rings on the rotor are clean.
    regulator can be diode checked. but the true test will be the running voltage

    good battery should read 12.8 volts as a standing voltage .
    when cranking starter you want battery to stay above 9.8- 10 volt mark to fire tci.

    when running typicaly at 2krpm you want to see 14.8 volts output
     
  9. mark1911

    mark1911 Member

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    I don't mean to sound dumb but what do mean when you say ohm out the components and diode check not really competent with electricity and a multimeter.
     
  10. Rooster53

    Rooster53 Well-Known Member Premium Member

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    I have a Haynes manual and it is very poor when diagnosing charging problems, it does cover the resistance checks on the stator and brushes - section 28 on page 8-20. It doesn't really give any help on diagnosing the Rectifier / Regulator.

    I would suggest start with the charging voltage as XJ550H suggested and we can go from there if it is not charging.

    And get those safety circuits working - they are there for a good reason.
     

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