No spark on my 75 CB550F
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No spark on my 75 CB550F

This is a discussion on No spark on my 75 CB550F within the Technical forums, part of the Caferacer.net Forums category; Howdy...hope someone can help me out. I don't have spark on my CB550F. I bit of history on the bike; I just got it last ...

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  1. #1
    kine8282`'s Avatar
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    No spark on my 75 CB550F

    Howdy...hope someone can help me out.

    I don't have spark on my CB550F. I bit of history on the bike; I just got it last weekend from this guy who said that he was changing the handle bars and once he finished he couldn't get it started. A buddy on mine just came over this morning to look at it...checked the usual suspects; points (good), battery (new), plugs (good condition). Electronics was his kryptonite so he couldn't figure out why I wasn't getting any spark.

    I lights and horn work so I don't think its the battery. I just checked the birds nest of wires behind the headlight and everything seems to be in order, I did find a brown female connector without a partner but according to my Clymer brown is for the taillight and that works just fine.

    I was trying to find a thread for this on the forum but nothing was working...can anyone offer help? Thanks.





  2. #2
    Senior Member kenessex's Avatar
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    Since you ar not getting any spark on any cylinders then the problem has to be either power to the coils or kill switch. Check the wires from the ign. switch and the wires from the right handlebar switch. Off hand I don't recall tthe color codes for sure but I think the switched hot from the ign switch to the coils is solid black and the kill switch is black with a white tracer(possibly yellow). If the insulation for the kill switch wire got cut or pinched during the installation of the handlebars it will be shorting out and killing the spark. If you unlug the kill switch wires and the bike has spark then your culprit is somewhere in that circuit. If that doesn't fix it then check to see if you are getting 12V to the coils at the black wire, not the yellow or blue(they come from the points).

    Good Luck,
    Ken

    AHRMA 412
    Vintage racing - old guys on old bikes

  3. #3
    kine8282`'s Avatar
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    Thanks for the reply, I took open the kill switch and found that the wires attached to it look good...i mean that it looks like the wires are still soddered on to the little circuit board, how do i know that its not working right? Is there tell-tale signs that its broken?


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  5. #4
    Moderator joe c's Avatar
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    which year is it?? the 77 and 78 models have a piece of crap for an ignition switch. it can be really finicky. which year is it?? you can jump the poles if its a 77 or 8 and that would tell you if its the switch. while he was yanking it around, he obviously loosened something. check your fuses too. under left side cover in a little box maybe.

    jc






  6. #5
    Moderator joe c's Avatar
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    i personally think youre searching the wrong places pulling things apart. check the easy stuff first. the keyed switch if its a 77 or 78 is really easy to remove and its retarded how its put together. i wouldnt be pulling apart the tricky stuff because you could compound the problem. search the easy stuff first.

    and get a voltmeter. or at least a continuity tester.

    jc






  7. #6
    Moderator joe c's Avatar
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    duh, its a 75.

    JC






  8. #7
    Senior Member Geeto67's Avatar
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    75 meaqns that the wires run inside the handlebars. I had a problem like that on my cb750 last year where the kill switch wires had frayed inside the handlebars and were shorting out. Unfortunatly the only way to check this is to pull the bar switch and visually inspect the entire length of wire so I suggest it as a last resort. Check the coils for cracks and check the coil grounds before you go ripping your handlebars apart.


  9. #8
    Senior Member kenessex's Avatar
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    Ok, I just looked at a wiring diagram and the hot lead to the coils is a b;ack ith white tracer. It comes straight from th ill switch. At the coils see if the blackw/white has power if the ign switch is on. If it does then the you should have spark. If it doesn't then pull out the headlight and sart checking the wires in there. This is a simple process if you follow the steps. You don't need to tear switches and stuff apart yet.
    1. Unplug the connetor for the ign. switch. White rectangular plug. Is the Red wire on the main wiring harness hot(12v)? No? Check your main fuse or battery connection.
    2. Check the ign switch for continuity between the red and black. With the switch off no continuitty, switch on there should be continuity.
    3. check the connectors from the right handlebar switch. (individual connectors) Check the black to the switch, is it hot with the ign. on? Check the Black w/ white tracer, with the black wire connected is the black w/ white hot with the ign switch on? If not, connect the black straight to the black with white tracer bypassing the kill switch. Spark now?

    Somewhere in these steps you should find the problem. It isn't rocket science, just take your time and be logical.

    Ken

    AHRMA 412
    Vintage racing - old guys on old bikes

  10. #9
    Senior Member Geeto67's Avatar
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    also check the plug wires, make sure the boots are tight and the electodes are making connection. plug wires are probably the most often overlooked item on an old honda.


  11. #10
    Senior Member kenessex's Avatar
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    Just in general, when dealing with an electrical problem always look for common factors. In the case of Honda ignition systems on 4 cylinders, they run paired ignition systems. That means that if the spark is missing in cyl. 1&4 or 2&3 together then the problem is in the coil or points or the feed or ground to that coil. If the spark is missing in only 1 cylinder then the problem is the wire, cap or plug. If the spark is missing in all 4 cylinders then the problem must be in the power to both coils which comes through the ign switch through the kill switch to the coils. Again, with the twins with 2 coils, try and isolate it to one side or the other or if spark is missing from both cylinders look for the common factor. If possible, get a wiring diagram and start tracing wires. The other nice thing about Honda is that their color codes are consistant throughout their models, so any Honda wiring diagram will give you a good idea of what to look at.

    Ken

    AHRMA 412
    Vintage racing - old guys on old bikes

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