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Thread: Running on one cylinder

  1. #1
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    Default Running on one cylinder

    Sooooo having put the bike in the living room sprayed up all the parts over the festive season I had the carbs off and put a stage 3 sigma jet kit in the carbs and put everything back togeather started the bike with no issues! she was running sweet untill put the bike outside to go for a run and now im only running on one cylinder the vertical one to be exact the front is not firing.

    I took the plug out it had fuel on it but not enough to flood it or stop it from fireing cleaned it up burled the bike over with the plug to the cylinder head and I had no spark at all I bought a new set of plugs and a coil which I just fitted and i am still running on one.

    Tired fireing up the bike a few more times to no luck although I did see this wire coming from my casing smoking like hell so ive just stopped before i end up burning the bloody thing to the ground.

    There was heatshrink over the connectors but they melted off.

    Attachment 12264Attachment 12265

    help im at a loss and getting @@@@ed with the thing after doing everthing to it over winter
    Last edited by wulfie; 26.02.2019 at 07:49 PM.
    If it Dosent rattle .....Somthings broken!!

  2. #2
    Join Date
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    Wulfie, there is a problem with your attached pictures, they're not showing.
    The carbed bikes effectively have 2 independent ignition systems, one for each cylinder, so some fault finding can be done by swapping round coils and ignition modules, one at a time. Not so easy for the pickups though as they are inside the alternator casing.

    The wires coming out of the casing are;
    The alternator wire (thick 2-core black cable with yellow insulation on the internal wires) which connects to the regulator
    2 x thin black 2-core wires from the ignition pickups, one to each ignition module.

    There is no supplied voltage on the pickup wires, they provide a small very low voltage pulse to the ignition units.
    The alternator wire handles quite a heavy current at maybe 20V or so under normal circumstances but if the regulator is faulty and is short-circuited internally there will be a lot of current which will burn the wires and probably the alternator stator.
    By your description it sounds like that's what's wrong with your bike. The lack of spark could be because the the regulator is pulling the battery voltage down or the heat has damaged the pickup wire for the horizontal cylinder.
    Try uploading the pictures again so we can get a look.

    Old enough to know better, young enough not to care

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  4. #3
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    Yes it was one of the two wires in the main cable that melted hopefully this picture works this time.

    I have no idea if it is supposed to have those crimp connections on it but I get the feeling they have been messed about with.
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    If it Dosent rattle .....Somthings broken!!

  5. #4
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    Yes those are the alternator wires and those are not the original connectors. They are well known for overheating and burning out usually because they get corroded which creates a resistance to the current. Replace them and pay attention to the state of the wires. Make sure they are clean copper where you fit the new connectors and that the insulation isn't melted. Once you have fixed them put a voltmeter across the battery, start the bike and check that you are getting around 14V at 2,000 rpm. If not the regulator is probably duff.
    This might not fix your non-running cylinder but it will be one less problem to deal with.

    Old enough to know better, young enough not to care

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  7. #5
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    Will do Derek I just got my wire stripper's and some new wire from work to do that tonight I'll solder and shrink wrap it further down and I'll make new connections at the top.

    Should it still put out 14v at the battery even with the bike only running on one cylinder?
    If it Dosent rattle .....Somthings broken!!

  8. #6
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    Yes, as long as the engine is turning over fast enough.

    Old enough to know better, young enough not to care

  9. #7
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    Quote Originally Posted by wulfie View Post
    Yes it was one of the two wires in the main cable that melted hopefully this picture works this time.

    I have no idea if it is supposed to have those crimp connections on it but I get the feeling they have been messed about with.
    Don't remember seeing them buddy, definitely not my handiwork. Need to let us know how it goes. I hate those preinsulated things, every bike I get I always find a couple used badly.

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  11. #8
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    haha not blaming you mate at all I follow your handywork fb and I know its far better than that

    Although I do have a development! I cut both wires back to some much fresher stuff just to be sure made two temporary connections just to get the bike running to test the voltage going to the battery.

    At 2k revs i had 13.95 V charging the battery AND the front cylinder was firing at least till I ran the bowls dry with the tank off.

    I dont suppose maybe the coil just wasent getting enough juice from the altenator with cable being corroded and then kamikazing itself into a burnt mess?
    If it Dosent rattle .....Somthings broken!!

  12. #9
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    Good news and the alternator and regulator are OK. The coils get their power from the battery and as long as the battery volts are high enough they should work fine. Maybe the coil wasn't firing with the battery being down a bit because it wasn't charging, but it's working now so get out on the bike

    Old enough to know better, young enough not to care

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  14. #10
    Join Date
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    Aye i just need to throw the thing back togeather now and wait till the next break in the weather!

    Thanks for the help!!
    If it Dosent rattle .....Somthings broken!!

  15. #11
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    No worries buddy, I’m just annoyed I missed the buggers is all. I fitted that seat cowl to the 750, I’ll send you a pic when I get a minute. Looks bloody good.

  16. #12
    Join Date
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    awesome man glad you are happy with it
    If it Dosent rattle .....Somthings broken!!

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