Bike runs bad with lights on

Discussion in 'Electrical' started by pitbull883, Oct 15, 2013.

  1. pitbull883

    pitbull883 Member

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    My 2001 883 runs bad with the lights on. It runs fine without the lights on, but when I turn them on it sputters a bit. I have about 12.6 volts at the battery with the engine off, and about 14.5 with it running. It doesn't seem to fluctuate with rpm changes. The idle speed changes when turning the light on and off. The bike has a new coil, new ignition switch, and the battery is about 2 years old, and I use a battery tender. I am suspecting a wiring problem because the wiring seems a bit butchered. Any advice would be appreciated. Thank you.
     
  2. Hoople

    Hoople Account Removed

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    Your saying you have 14.5 volts at the battery during idle speed?

    If the voltage reading at the battery with the engine running at idle is 14.5 volts,, is that with the lights on or off. Also need to know what the voltage at battery is with engine running at idle with the lights on.

    Also, the coil has a white/black wire primary wire going to it. What is the voltage at that wire with the engine running at idle with lights on..
     
  3. pitbull883

    pitbull883 Member

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    I will check that and report back here later.
     
  4. Jack Klarich

    Jack Klarich Expert Member

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    Have you load tested that battery and checked the cables?
     
  5. pitbull883

    pitbull883 Member

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    I checked it after my ride home from work.
    At idle, at the battery, I have 14.4. At idle with the lights on, about 13.4.
    At the coil at idle about 14.4. At the coil with lights on, about 12.4.
    It also seems that the brake light affects the idle.
    I will check the cables, and all other connections when I get a chance. I should be able to have the battery load tested at work (I work at a car dealer).
     
  6. Hoople

    Hoople Account Removed

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    Is all this accurate=> The bike is a 2001 that has a carb. The coil has been replaced for this problem and it didn't help. The ignition switch has been replaced for this problem and it did not help. The ignition system is factory stock and the bike still uses the factory integral timing plate. Overall, the ignition system is factory stock.



    Does the bike perform poorly (mis-fires) under wide open throttle in 2nd or 3rd gear. Since it's dual fire, have you metered out the spark plug wires just to see what the values were. If you can, slide one spark plug boot down the wire a bit to expose the metal clip. Now with the bike running, pull the wire off the plug and see how much gap (in distance) you can reach before the engine stalls. Don't get zapped by the spark. Can you pull a 3/8" spark gap before the engine dies.
     
  7. pitbull883

    pitbull883 Member

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    Yes, you are correct about the parts that have been replaced.
    As far as I know the ignition is stock.
    A little more about the bike: The bike itself is a 1988. As far as I can tell by the VIN, the engine is a 2001. Also, like I said the wiring is kinda hacked.
    The carb is an S&S shorty E.
    I had a problem last year fouling plugs. I replaced the coil thinking it would help that. The ignition cylinder was replaced in the spring when I first noticed the problem when the lights on. At first this drew my attention to the ign cylinder, and at that time I noticed that the key was very loose, as was the back part of the cylinder. Figured whether it helped or not replacement was a good idea.
    Also last year I found out that the lights didn't HAVE to be on to ride the bike. The first notch you can run the bike lights off, the second and the lights come on. I stopped riding with the lights on, and I have not fouled a plug since. Coincidence? I don't know, but it's all starting to sound related.
    It seems to run fine under WOT in 2nd and 3rd gear. Actually in all gears.
     
  8. Hoople

    Hoople Account Removed

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    Injected bikes will offset idle RPM due to small outside engine loads but carb bikes do not. But I wouldn't expect much of a alternator load due to turning on just the brake light bulb.

    Try this in order to narrow down the issue. Get a 3 foot piece of 14 gauge wire (can be thicker but not thinner) that has an alligator clip on each end.
    Clip one end to the stud on the coil that has the white/black wire going to it. The other end will clip onto the battery... directly to the positive terminal of the battery. You may see some arcing as you connect the wire.

    Start the bike. Does the idle rpm still change exactly like it did before when you put the lights on.
    (You are bypassing the engine kill & ignition switch so the bike won't shut off until you remove the jumper wire.)

    If the fouling of your plugs was being caused by an electrical issue, I would think performance issues would also happen at WOT.
    Do you know if the heat range of the plug is correct (your using what the book calls for).

    Also try to perform that spark gap test (spark gap) in order to see how much reserve voltage you have in the ignition system.
     
  9. Jack Klarich

    Jack Klarich Expert Member

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  10. Hoople

    Hoople Account Removed

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    PitBull, you may want to hold off testing with the jumper wire until you can confirm the schematic for your bike. My diagrams for are totally different than what Jack shows. Major differences from 1988, 2000, 2001.

    There are more wires and modules on bikes earlier than 2001. I go totally by schematics.
    Jacks diagrams are totally different than what I am looking at. So I have no clue which diagram to use at this point since the frame & harness are from an '88.