who was it that posted about the speedo on e-bay?

Discussion in 'General Questions' started by motorpsycho, Sep 24, 2009.

  1. motorpsycho

    motorpsycho Active Member

    a few days ago there was a post about speedometers. someone posted a link to a digital, battery powered speedo on e-bay for $2.94 (from hong kong).
    i'm just wondering if they got it to work (whoever it was said that he bought 3 of them).
    well, i bought one and i did get it to work...until i started my motor.
    as soon as i start the motor, the speedo wigs out, resets itself, and then all the numbers lock on 8888888.
    it works fine without the motor running, and i tried several different things to isolate it from touching anything on my bike. i even went as far as taking it completely off my bike and holding the entire thing in my hand. sitting on my bike i can fire the motor up with the speedo in my hand, and it does the same thing as when it is attached to the bike. (resets, and all #'s lock on 888888).

    i was just wondering if the other guy got his to work, and if he had the same problem that i am having.
    since this thing is battery powered, and is totally encased in plastic, i can not figure out why it messes up when i start the motor. I even went as far as totally disconnecting my cdi box from the frame thinking that it is sending current out to the frame.
    for some reason, it seems like my entire frame is "charged" when the motor is running. i had the same problem when trying to hook up a headlight to the white wire....but that's a whole different story.
    all of my wiring has been soldered, sealed with heat shrink, and wrapped in plastic convolluted tubing. no bare wires are touching anything, and my motor is isolated from the frame with rubber pads.
    i can not figure out what is causing this.
     
    Last edited: Sep 24, 2009

  2. The magneto must be sending strong "radio" type electro magnetic waves out. I'm not sure how to isolate a device from such signals. Any radio savy types might be able to help with this problem
     
  3. Shadeslay

    Shadeslay Member

    Normally a shielded plug wire will do the trick.
     
  4. Porkchop

    Porkchop Member

    Is the speedo a wireless unit ? I haven't read of problems with wired units. I have a wired Schwinn and have had no problems.
     
  5. motorpsycho

    motorpsycho Active Member

    well as far as being wireless...yes and no.
    it is battery powered, and the battery is housed inside the speedo head.
    the sensor that leads to the front wheel is wired to the speedo head and there is a magnetic pickup on the spokes.
    even if i remove the entire unit from the bike and just hold it in my hands while i'm on the bike with the motor running, it will re-set itself and lock up.
     
  6. Dilly Bar Rob

    Dilly Bar Rob Member

    Yes a shielded plug wire should solve this. Even just an automotive grade (resistor) plug wire may be enough to cut the RF interference to a reasonable amount. There is a reason why they don't use copper wires (anymore) to the spark plugs in cars....


    When I lived in europe one of our neighbours drove an old "Trabant" car - 2 cylinder aircooled 2 stroke, 600cc, fiberglass body, points ignition with 2 coils and unshielded COPPER wires to the plugs... If you were watching TV off of an antenna & he was out driving the picture would go crazy a LONG time before he drove by. Electric spark is THE ultimate RF interference creator.
     
  7. Al.Fisherman

    Al.Fisherman Active Member

    It was I that posted about the speedometers on E-Bay. I have the same problem as you mention. I'm working to solve the issue with a resistor plug wire as mentioned. The plug wire that comes in our kits are in fact wire. Might only be about 5 strands the thickness of a hair but wire none the less.
     
  8. motorpsycho

    motorpsycho Active Member

    i have a bunch of extra resistor plug wire left over from when i made the plug wires on my 55 pontiac. how do i get the resistor plug wire hooked up to the cdi box?
     
  9. Shadeslay

    Shadeslay Member

    Just screw the wire on to the cdi. There's a screw in the center, so it just threads on.
     
  10. motorpsycho

    motorpsycho Active Member

    ok, that was easy. the way the cdi looked, it looked like the wire was molded into it and sealed.
    i unscrewed the wire and put on a nice peice of red accell 8 mm superstock resistor plug wire in place of the old wire. it took me about 10 minutes to do it.
    i'll see if that makes a difference tomorrow....it's too late at night to run the motor right now
     
  11. Stink Bike

    Stink Bike Member

    I had the same problem so I am now using a good old fashioned mechanical speedo like the one's from before computers.
     
  12. motorpsycho

    motorpsycho Active Member

    yeah i tried a mechanical speedo as well. it only lasted about 2 days. (this was a new "retro" style speedo which is 98% plastic.) and at 60 k/mh, the plastic gears in the drive mechanism broke. well, it read 60 k/mh...not sure how accurate it was, but i was hauling butt when the speedo drive busted.
    the gears in it were literally disintegrated, and melted. i don't think it was ever meant to go as fast as i made it go. i'm petty sure that it was designed for a peddle only bike that might hit 30 k/mh tops.
    if i could find a cheap old mechanical speedo with metal gears, and that is built like they used to make 'em, i think it would last.
     
  13. motorpsycho

    motorpsycho Active Member

    well i put a sheilded, resistor plug wire on my bike and tried the digital speedo.
    it still does not work when the motor is running.
    it does the same thing that i described before.
    this stinks because i REALLY want to know how fast my bike is.
    i'm trying to establish a baseline speed average before i add some hop up parts to see how much of a gain /loss i will get as far as speed goes. i'm wanting to add an expansion chamber and a high flow k&n style air filter.
     
  14. Al.Fisherman

    Al.Fisherman Active Member

    Dang...hate to hear that about the spedo...well there are going to be 3 happy kids around here when I give them away.:devilish: I'm going to try and see how far the wire will stretch away from the pickup and see if it settles down. Could be vibration, or electrical field causing the problem. I have a mechanical spedo but would really like to see these things work. Nothing ventured nothing gained...at least they were cheap enough. Have 25 miles on it so far....all around the .7 mile circle I live on.
     
    Last edited: Sep 26, 2009
  15. motorpsycho

    motorpsycho Active Member

    yeah that's the way i feel too. heck , the speedo was only $2.94 including the shipping from hong kong. i took mine all the way off of my bike except for the sensor, and laid the speedo head on the ground. it still locked up. since the sensor on the forks with the wire coming out of it was technically still touching the bike, i am thinking that it has to do with what you say. the electrical field around the bike. i can remove the entire speedo including the sensor and all that, hold the entire unit in my hand while sitting on the bike with the motor running, and it still acts up. the only way i can get it to work is without the motor running.
    but it's no big loss at $2.94...but i was really hoping to make it work.
     
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