Welcome to Our Community

Wanting to join the rest of our members? Feel free to sign up today.

Sign Up

Speedometer sensor

Discussion in 'Freebies' started by Chopperdave70, Nov 3, 2011.

  1. Chopperdave70

    Chopperdave70 Member

    Joined:
    Oct 29, 2011
    Messages:
    25
    Likes Received:
    0
    Trophy Points:
    0
    Location:
    Kentucky
    My Bike(s):
    Big dog chopper
    First Name:
    David
    In trying to find a speedometer sensor for my big dog i have a new one that does not work in my bike but if it will work in yours and you need one let me know. The one i have is part# BD4122 04R it would not work in my 04 chopper but may in older models.
     
  2. jlohman276

    jlohman276 Member

    Joined:
    Apr 7, 2011
    Messages:
    28
    Likes Received:
    1
    Trophy Points:
    0
    Location:
    juliaetta Id
    My Bike(s):
    03 big dog chopper 107 with magna charger
    First Name:
    Jeff
    do you know if it will fit an o3 big dog chopper with the baker 6 sp ???
     
  3. Todd W

    Todd W Member

    Joined:
    Jan 14, 2018
    Messages:
    15
    Likes Received:
    3
    Trophy Points:
    3
    Location:
    Frankfort In
    My Bike(s):
    03 chopper
    First Name:
    Todd
    My 03 speedo quit last week after ignition went out. I replaced ignition with ultima kit and fired up runs great. But no speedo ??
    Light comes on and odometer is on but when key goes on it jumps down and back to zero and will not work :(
    I got a 2 wire sensor, can anyone explain how the circuit works from sensor to speedo ??
     
  4. Sven

    Sven Well-Known Member

    Joined:
    Mar 4, 2012
    Messages:
    1,624
    Likes Received:
    832
    Trophy Points:
    113
    My Bike(s):
    building one
    I can only go so far explaining. Start with the 2 wire sensor. Is it magnetic or find the little core or short dowel looking thing out of the plastic covering? If so, that makes the AC current. The star wheel off the sprocket nut or said design has 4 corners? So the sweep of the leading edge and trailing edge causes a wave pulse of current up the wire. The faster the 4 bumps pass the magnetic sensor, it heads up the wire off of a leg of an integrated chip (IC). Integrated chip is now on a motherboard. Pulse is sent thru something called 'truth tables.' In other words, a balance of checks and rechecks and bingo the speedo number, the clock number, the radio dial number. Find an EE to design the breadboard so you have a speedo to match the 2 wire sensor. and that's all she wrote on this end. Look up integrated chip, truth tables, electrical breadboard, and for each one, hit photos or the other name that is on the menu bar to see what you're up against designing a speedo from scratch.

    If I were in meguyveer mode, I'd veer over to a simple tach that works off a spark plug wire. Cut a round face out with an eighth inch slit that carves the arch of the tach. This way I can see the needle. I'd write the gear number I'd have to be in with same numbers, then the mph number in a larger number. 65mph in top gear is where at the tach? 40 and 25mph is all I need to fill in the rest.
     
  5. Todd W

    Todd W Member

    Joined:
    Jan 14, 2018
    Messages:
    15
    Likes Received:
    3
    Trophy Points:
    3
    Location:
    Frankfort In
    My Bike(s):
    03 chopper
    First Name:
    Todd
    That was way too much info ,lol
    I quess my question is, should I have power 12Volts on incoming side of the sensor ? I pull up a diagram and it shows a 3 wire for 03 chopper ?? Mine is original and I only has 2 on the small connector and sensor. Black and white on connector side ?
     

Share This Page