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Lights out - CB250

Discussion in 'Technical and Troubleshooting Torque' started by Short one, Nov 8, 2015.

  1. Been transforming my bike into a cafe racer last week finishing touches did some welding disconnected ground moved some wiring etc. Went to start nothing no lights ignition nothing at all checked fuses ok power on starter solenoid relay on both red wires until I plug the connecter on the top then nothing is this relay cactus or should I be looking elsewhere. Can someone explain who it basically works.

    Thanks Shorty

  2. trace where voltage gets to with multimeter
  3. There are four wires on the connecter one red goes to ignition the other red to the rectifier. One to a diode and one too the starter switch. Both red spade terminals have voltage until I plug on the connecter then voltage is not there?
  4. Update voltage on both red terminals until I turn the ignition key to the on position.
  5. Check the wiring to the ignition switch and the wiring to the kill switch for voltage readings.
  6. Have voltage reading on red wire until I turn the key to the on position then nothing at all obviously nothing at the kill switch.
  7. It 'could' be a faulty ignition switch...
  8. Is it possible to check the ignition switch or bypass it?
  9. What is the bike based on?
    Do you have a wiring diagram for it?
    • Funny Funny x 1
  10. café racers are supposed to be unreliable..
    • Funny Funny x 2
  11. It
    Its a 2000 cb250 I do have a wiring diagram, I think it is probably the ignition switch just want to make sure before I order a new one.
  12. Multimeter then, measuring between the frame of the bike (Battery Negative) and the ignition switch, you should have 12volts on the incoming supply and zero on the other side with the switch off and 12volts when on. The CB250 had a second set of terminals to leave the parking lights on I believe as well so from your wiring diagram work out the appropriate wire colours.

    From what you say above you are either:
    1. Measuring across the swicth in which case when the switch closes the voltage will drop to zero as you describe.
    2. There is a high resistance connection that when the switch closes and the circuit draws current the voltage collapses.
    SO if you aren't doing so then make all measurement with respect to the bikes frame, i.e. negative of the multimeter on the frame or battery negative.
    • Agree Agree x 1

  13. Ok as discribed below checked from the frame ground

    Off Position
    Red from main Fuse to ignition =12 volts
    Black wire thats goes to secondary 10A fuses = 0 volts
    Ground= 0 volts
    Black/ White that goes to Kill switch-= 0 volts

    ON Position
    Red from main Fuse to ignition= 0 volts
    Black wire thats goes to secondary 10A fuses = 0 volts
    Ground- 0 volts
    Black/ White that goes to Kill switch- 0 volts
  14. Given those results, I think cjvfrcjvfr is on the right track.

    Check very carefully all the connections starting from battery positive to main fuse, the fuse itself and the fuse holder and then to ign switch.
    Particularly examine the plug-in fuse itself, they can develop hairline cracks which prevent proper flow of the voltage when the circuit is under load, but look OK on casual inspection. For the sake of a couple of bucks consider just replacing the fuse anyway. Also very carefully check the fuse holder and make sure that it is making a good connection with the fuse. These sometimes get heat damaged/corroded and fail.

    If you can, repeat your ign on test, but this time probe with the multimeter all the intermediate points (fuse/fuse holder etc) between battery + and ign switch, you should pick up a spot where you have volts, then the next spot shows nothing, between those two places is your problem. Battery neg is still the reference point for all this.
  15. Im now thinking the battery could be cactis, I pulled it out to put some load on it nothing, whacked it on the charger wont charge. I will replace it tomorrow, perhaps that has been the issue all along.
  16. Ok, collapsed cell then possibly in the battery. It will not show itself until you try and draw load. Bad battery can be a sign of other charging issues so when you replace it check the voltage across the battery when the bike is revving to cruise revs. It should be 13.5 - 14.8 volts. Much more it is overcharging which will kill batteries, much less and it is under charging which flattens and eventually kills batteries. :)
    • Agree Agree x 1
    • Winner Winner x 1
  17. Hopefully thats sorts i,t thanks heaps for the help
  18. How old is the battery?
  19. Not sure definately more than 12months
  20. If only a year or so old its unusual for a battery to collapse so completely. That's not to say it doesn't happen though.

    If you can, run some jumper leads from a car to the battery terminals and see if the bike starts. That would almost completely prove that it's the battery as the problem.