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Help electrical bike problem

Discussion in 'Technical and Troubleshooting Torque' started by Noggin, Jan 31, 2013.

  1. 2008 honda cbf250- 10500km's- 3/4 tan of fuel.

    Today after riding home from work (1hr) in the sun. An hour later i hoped back on the bike to go out but when i put the key to the on position the dash flashed like normal for a second then just cut off and i could not start the bike at all, nothing happened when switching from off to on (can't be a flat battery as i didn't leave the lights on).

    So i jump started it, i noticed the lights on the dash would flash on and off and the dash and headlight at low revs were dim, at high revs it was like normal. I went around the block and 100m up the road the speedo needle got stuck at 60hm/h and the rev needle got stuck around 5000 revs, the indicator light would flash really fast or just stay on. When i turned off the bike the dash lights would go off and i would have to jump start it again to get it going.

    Last week i got extremely wet on the way home when i was 15 mins from home, but i have ridden it to work for the last 2 days (1hr each way to work so 4hrs) and it has been fine.
    Took the battery out and is still reading 13v.

    Anyone have any idea what it might be, my guess is something got wet. And here i was thinking bikes can be ridden in the rain :rolleyes:.
    Thank you,
  2. Measure the battery voltage when it is connected and the motor reving. It may be charge circuitry i.e. Regulator Alternator.
    You may be right though and it is water in one of the connectors. A good place to start though is to know the battery and charge circuitry is intact then move on. Check the connectors to the key switch to see if it is tight, disconnect and reconnect it to see if it is loose.
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  3. As CJVFR says first check is the battery.
    If it will start with a jumper battery, but not start on ots own my bet is the reg/rec has gone and the bikes battery is now flat (and possibly stuffed too)
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  4. #4 Noggin, Feb 2, 2013
    Last edited: Feb 2, 2013
    Okay thanks for the help, took the battery out and tried it on a mates bike and its flat/ probably stuffed. Tried his battery on mine and the dash lights came on like normal, but when i go to start it tries to turn over once but then i get a ticking noise from around the 'magnetic starter switch', so i can only assume it's that.
    How would i go about testing the 'magnetic starter switch'?

    Edit: I'll get the battery tested tomorrow at battery world tomorrow to make sure i need a new one.
  5. The Starter Solenoid is what you probably mean. Are you sure it is this clicking in and out or if it is an even repetitive sound then it could be the starter motor not engaging. A lot of these problems can be bad battery connections, make sure the battery terminals are clean and that the main connections to the battery are tight.

    From what you describe I would say you have a charging problem and possibly a stuffed battery.
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  6. My mate wasn't able to stay for long so i could only do the quick simple tests :-(. Can you use a car battery in place of the bike battery so i can continue the testing?
  7. Yes, you need a good solid high current connection to the battery. Use car jumper leads, connect the negative to the bike frame and connect the positive and insulate it using rags or tape so it doesn't short out on the bike frame.
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  8. #8 Noggin, Feb 3, 2013
    Last edited: Feb 3, 2013
    Okay, so i wasn't too keen on scratching back the paint on the frame to get a good connection with jumper cables, so today i got a new battery and it starts right up :].
    How many volts should i be seeing with the bike is reving? on a brand new battery it is showing 13.5v when on idle (1000rpm), at 3000rpm it's 13.76 and rises by .01 every few seconds or so. When the bike is off it's 13.08.
    Thank you very much for your help so far cjvfr (y)

    Edit: the voltage on the battery seems to be going down slowly when i have the bike off and no lights or anything on. It's at 12.98 now, so every minute or so it goes down .01v
  9. Roughly 12,5 at "rest" for a charged battery and between 13.8 and 14 or so with engine revving.

    if the rest voltage drops to below 12.3 or so you've probably got a constarnt drain (like an alarm or something), To check it, disconnect the negative battery connection place multimeter on AMPS DC, and put aone probe on the battery terminal and one on the (disconnected) connector. if it shows more than about 20mA it would be wise to plug in a charger when you leave the bike overnight.
    This is very simplified advice, if in any doubt gte an auto elec to check it out
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  10. +1 to Ducfreak, you don't seem to be getting in to the battery charge voltage range so your battery will just get flatter and flatter.

    You may have a current drain somewhere as well but faulty regulators can exhibit this kind of drain. I would be suspicious of your regulator given the voltage you are getting when reving the engine. You can disconnect it and see if you still get a drain and do the current check test as described by Ducfreak.

    Be careful to change your multimeter back to voltage when you finish or you can damage your meter if you start testing for voltage then.
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  11. I let the bike run for a bit and the voltage at idle plateaued at 14.4v, then i let the bike rest for 5.5hrs and ended up with 12.83v which was going down extremely slowly over time (roughly .10v/hr since turning it off). Anything sound suspect there?
    I haven't done the drain test yet but will in a minute.
  12. All sounds spot on, i'd say the battery had just died.
    Just keep an eye on the batt volts for a day or 2. BUT definitely sounds sweet now.
    You may have had a loose battery connetion initially that led to the stuffed battery or it just died :cry:
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  13. Did the battery drain test and it came up with around 15ma but decreased quickly if i kept testing prongs connected.
    I'll check it frequently over the next few days and see what happens.
    Massive thank you to cjvfr and Ducfreak, you both helped me so much (y).
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