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Alternator Fire!

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  • Alternator Fire!

    After finally getting the CBR 600 back together I took it out to get some fuel before a trip down south, did a lap around the block and when I returned home to pick the Mrs up, switched the bike off the noticed smoke coming from under the seat!

    Long story short, Ive found the wires that melted/caught on fire

    According to the electrical diagram, these 3 yellow wires run from the Alternator:

    To the Regulator/rectifier:

    As shown:

    The only things I have changed on the bike since I last rode it are:
    New ignition barrel
    Front Indicators

    Any idea what has caused the wires to melt and burn like this?
    Could it just be a simple bad connection?
    Can i just rewire the connectors?

    Any help is much appreciated!
    Theirs no replacement for displacement

  • #2
    Im thinking the most likley thing would be that they somehow came into contact with each other or somehow earthed themselves causeing sparks which would have melted the wires, or maybe the alternator was overcharging causing the wires to heat up from to much current? rewire it and check the charging voltage before you go riding again.


    • #3
      This thread is relevant to your interests


      • #4
        Awsome, thanks Bendito!.
        Looks like I have stator
        I have a feeling I might have a bad earth somewhere on the bike, would that have contributed/caused my problems?
        Theirs no replacement for displacement


        • #5
          Couldn't say

          I posted this a while ago
          There's a link to a good fault finding guide in there if you are handy with a multimeter


          • #6
            would be more likely a short, What a bummer man!!!


            • #7
              Scary resemblence to my situation. All the best with it mate. That guide that Bendito posted is perfect for sussing it all out.


              • #8
                When you replace the connector, make sure you get one rated to handle the current.
                I made the mistake of using any old connector and the result was like you first photo.
                I just hard wired in the end.

                Good luck mate
                Respect is earned, not enforced.


                • #9
                  Thanks for the help guys, much appreciated
                  Theirs no replacement for displacement


                  • #10

                    OK, ive finally had time to have a look at the bikes electrics:

                    I have replaced the burned out plug with a new one from Jaycar and performed the following tests:

                    With the system full hooked up I get the following voltage across the battery:
                    At ~1400rom (idle) - 13.64 - 13.8 Volts
                    At 2500 rpm - 14.2 volts
                    At 5000 rpm - 13.88 volts

                    With ignition off - battery is at 13.22 volts

                    I then checked resistance between the 3 yellow wires from the alternator- 0.3 Ohms between all 3 (1 to 1, 1 to 2, 2 to 3)

                    OL between 3 wires and earth

                    I then checked the diodes (volts) on the rectifier/regulator:
                    0.48, 0.46, 0.48 volts between the 3 yellow wires and the red
                    and OL the opposite way

                    I did a "leak test" (disconnected the negative cable from the negative battery terminal, placed the negative multimeter lead on the terminal, and the positive multimeter lead on the negative cable) and got a reading of 0.00mA

                    Now this all seems fine to me but that doesn't explain why the plug melted and caught fire??????

                    Am I lucky and is my alternator (stator) and Reg/Rec ok and I just had a bad/dodgy/old connector that shorted out and caught fire?????

                    And advice would be great?
                    Theirs no replacement for displacement


                    • #11
                      bad connection/ crimp/contact between the 2 connectors bits, caused resisance, (High reading on ohms scale of multimeter) resistance created heat, melted the plastics because they are rated at 70 odd degree celsius.


                      • #12
                        Seems odd for the voltage to drop off at 5000rpm...
                        Does all of the wiring look good?
                        You tested 1 to 2, 2 to 3, 1 to 3 right?
                        Try test the same pairs again at say 5000rpm (AC volts) and see that the readings are all the same
                        hopefully the bad connector was the only problem, but if it was something else causing a "surge" and the connector was the first point of failure, them replacing the connector may just cause the next component down the line to fry instead.

                        That's just me thinking worst case, hopefully you have no more problems


                        • #13
                          Hmmm, just went and tested the voltage across the 3 wires at 5000rpm as you suggested, I get:
                          54.4 V
                          54.4 V
                          53.8 V

                          Is that enough of a difference to be concerned?
                          Theirs no replacement for displacement


                          • #14


                            • #15
                              Corrosion (from water spray, or just age) on those connectors is a common reason for them to melt and burn.

                              May be underlying issues which would cause the battery to under/over charge, but you'd know about them fairly quickly (bike not starting, instruments cutting out, more than 15v across your battery terminals at 5000rpm etc...).