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  • Electrical/electronics question

    Hello Again! Latest electrical question for you experts out there. Pycho Bike is back with a problem again, but this time it is different. The bike was running well, turned off at the end of a ride - all normal. Went to take it out again, and it wouldn't start - it would try, just not enough to keep going. Well, a quick check uncovered on of the coils not firing. Okay, I figure bad connection, all the usual stuff. I have spare coils but they made no difference, switch wires around and both coils are capable of making a very nice spark. Did all the usual checks, all fine. Here is where it gets interesting - at least to me. When I put a voltmeter probe into the connection of the orange wire at the coil and turn the switch on, it shows line voltage and when you crank the engine over, the voltage drops, but is still there - this is the coil that is firing. Do the same on the grey wire, you get line voltage until you crank it over, then the meter quickly jumps right to "OL" (open Line). I have never seen that before in all my troubleshooting in the past. A quick switch of the orange and grey wires at the coils revealed the problem clearly following the grey wire. Same readings at the TCI plug.

    Any thoughts on this? TCI problem (it was just gone over by DiVinci - terminals resoldered and tested - ran fine. Any ideas appreciated!

    Keith
    Current:
    1979 XS11F - "Sigmund"
    1975 Triumph T150V - "Ralph"
    1975 Honda CB125S - "Blue" - built for my daughter to learn on.
    1983 Kawasaki GPZ 550 - yet another bike that needs me! It followed me home...

    Previous:
    1975 Norton Commando
    1969 Triumph Tiger 650
    2002 Yamaha YZ250F

  • #2
    Are you familiar with a coil relay mod? It allows you to use source voltage from the battery straight to the coils to eliminate voltage drop from gremlins in the harness. It's kind of a round-about way of ignoring a definite gremlin in the system, but a sure way to get 12v to your coils. As far as your drop in voltage, have you confirmed that your charging system is intact via checking stator and r/r? If it was really your TCI, do what the shops do and swap in a good-working TCI and see if the problems persist. I'm sure there is a good fellow forum-member that would be willing to loan you a TCI for this test. A fellow on the GS Resources forum has a signature of "To measure is to know", which eliminates any assuming and guessing. Start at the battery with you DMM and probe away. Since you are getting some voltage at the coils, we can eliminate a possible short in the harness. Have not eliminated a resistance issue though. Since the Stator feeds into the TCI, have you done impedance checks on that to determine that it is good? What is the voltage of the battery before and after cranking? As revs increase, battery voltage increases? I'm sure you know all of this and by no means am I talking down to you, but, sometimes we forget about stuff that is fundamental to these bikes running. A bad charging system can cause a lot of issues on this bike.
    1979 XS1100F
    2H9 Mod, Truck-Lite LED Headlight, TECHNA-FIT S/S Brake Lines, Rear Air Shocks, TKAT Fork Brace, Dyna DC-I Coils, TC Fuse Block, Barnett HD Clutch Springs, Superbike Handlebars, V-Star 650 ACCT, NGK Irridium Plugs, OEM Exhaust. CNC-Cut 2nd Gear Dogs; Ported/Milled Head; Modded Airbox: 8x8 Wix Panel Filter; #137.5 Main Jet, Viper Yellow Paint, Michelin Pilot Activ F/R, Interstate AGM Battery, 14MM MC, Maier Fairing, Cree LED Fog Lights.

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    • #3
      Thanks Ian - can't hurt to look at everything again! Any info on the rely mod you mentioned?

      Keith
      Current:
      1979 XS11F - "Sigmund"
      1975 Triumph T150V - "Ralph"
      1975 Honda CB125S - "Blue" - built for my daughter to learn on.
      1983 Kawasaki GPZ 550 - yet another bike that needs me! It followed me home...

      Previous:
      1975 Norton Commando
      1969 Triumph Tiger 650
      2002 Yamaha YZ250F

      Comment


      • #4
        Check your pickup coil wiring. The smaller 4-wire plug at the TCI goes to them, you're looking for about 720 ohm between the blue/orange wires and the grays. Repair procedure here: http://www.xs11.com/forum/showthread.php?t=543
        Fast, Cheap, Reliable... Pick any two

        '78E original owner - resto project
        '78E ???? owner - Modder project FJ forks, 4-piston calipers F/R, 160/80-16 rear tire
        '82 XJ rebuild project
        '80SG restified, red SOLD
        '79F parts...
        '81H more parts...

        Other current bikes:
        '93 XL1200 Anniversary Sportster 85RWHP
        '86 XL883/1200 Chopper
        '82 XL1000 w/1450cc Buell, Baker 6-speed, in-progress project
        Cage: '13 Mustang GT/CS with a few 'custom' touches
        Yep, can't leave nuthin' alone...

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