speedometer won't work w/ engine on

Discussion in 'General Questions' started by crowvise, Aug 3, 2010.

  1. crowvise

    crowvise Member

    Had bought a $20 wallyworld "bell" speedometer. read fine w/o motor on. W/ motor on reads 56-62mph at comparable 12-15mph motor off reading. my 1st guess is the magneto and/or cdi was affecting it. 2nd guess vibration was a factor. Any similar experiences? Whats a decent, cheap speedometer. will the digital ones work on these bikes?
     

  2. Stan4d

    Stan4d Banned

    Is this a wireless speedo you are talking about? There is usually too much interferance for those, though some have found the sweet spot where it works.
     
  3. crowvise

    crowvise Member

    yep it is wireless. I returned it. But still want to know.
    Still 56-61mph pre break-in would have made my motor the :poop: :worship:
     
  4. AussieSteve

    AussieSteve Active Member

    You'll have trouble with a lot of speedos, even wired ones. Avoid the 'Sunding' brand from eBay, they reset every time the engine is started.
    I use a Cateye wired speedo now and have had no problems at all.
    Many people recommend the Schwinn speedos, too.
     
    Caplain likes this.
  5. TOTAL CARNAGE

    TOTAL CARNAGE Member

    I have two of the Schwinn speedos. Both the same. One works fine, one resets every time the engine is started.
    With the one that resets, I have moved it to the rear wheel, well away from any rf noise.....no good. Made the wire shorter.....nope. Shielded the wire and speedo.... :shout: .......saved it for a bike WITHOUT a motor....Yea!
    I guess you just have to get lucky. Some work, some won't. Even within the same brand.
     
  6. GearNut

    GearNut Active Member

    The ignition system creates EMI also known as RFI. This will affect all kinds of electronic gizmos ranging from bicycle speedos', radios, cel phones, cheap digital cameras, ect.
    As you ride your bike down the road it can easily affect the radios in the cars that you ride by. If they are listening to broadcast radio and not a CD or MP3 player they will hear a buzzing in the speakers at the same frequency as your spark plug is firing.
    http://en.wikipedia.org/wiki/EM_interference
     
  7. RedBaronX

    RedBaronX Member

    I bought one of the retro looking ones, and I can't get the danged thing to fit on my hub AND get the wheel back into the fork... I am generally a smart person, but I can't stand being thwarted by a really basic piece of machinery...
     
  8. AussieSteve

    AussieSteve Active Member

    At least if you do get it to fit, you won't have interference problems with a mechanical type.

    Like you, TOTAL CARNAGE, I tried shielded leads etc with the 'Sunding' speedo, but could never get rid of the problem. Sounds like it's the luck of the draw with Schwinn speedos too.
    With a wired speedo, running the wire down the front brake cable helps. That keeps it further away from everything.
     
  9. Bob Mac

    Bob Mac Member

    Try the resistor plug. That's all mine needed. I was ready to junk it until then
     
  10. GearNut

    GearNut Active Member

    Resistor wires, resistor spark plug caps and resistor plugs were all invented to reduce the effects of EMI/ RFI.
    Some ignition systems are designed to use all of the above, but I think it is overkill.
    I also would not recommend trying all of them at once on these cheap CDI ignitions.
     
  11. Bob Mac

    Bob Mac Member

    I just put the res. plug in and it worked fine
     
  12. crowvise

    crowvise Member

    where do you find a resistor plug(auto parts store-but make model?)? How much does one cost?
     
  13. crowvise

    crowvise Member

    You think a faraday cage built around the cdi would help?
     
  14. Bob Mac

    Bob Mac Member

    The plug is an ngk-bpr6hs I bought it from bikebandit.com
     
  15. GearNut

    GearNut Active Member

    No. It would have to encompass the CDI box, spark plug wire and spark plug; if we are talking stock components here.
    Just using a resistor plug should be quite sufficient.
    FWIW, it is a good idea to replace the junk stock spark plug wire anyways, regardless of the spark plug used. In doing so you can utilize a spark plug wire with a resistive core and get two problems solved at once.
     
    Caplain likes this.
  16. crowvise

    crowvise Member

    ok. Please recommend plug wire w/ resistive core. Approx price?
     
  17. crowvise

    crowvise Member

    I'm currently using on of the ngks recommended in one of 2 pre-build checklists. Don't remember which one but it was the only one 'Advance Auto' could order for me off the ngks listed in the pre-build thread.
     
  18. Bob Mac

    Bob Mac Member

    Yamaha and honda use these plugs in their bikes so any cycle shop selling these brands would be your best bet to buy. They run around $2.50 each. always buy a spare
     
  19. GearNut

    GearNut Active Member

    Any automotive ignition wire with a 90 degree bend is better than the factory wire.
    99.9% of the wires sold in auto parts stores are resistor core type, The center conductor of the wire will look black or dark gray, like a pencil lead, and seem to be made of flexable plastic. It is called graphite suppressor core wire. Ask the counter person for a single distributor wire or you may be able to get a good used one from a repair shop for free.
    Or if you would like to support a paying vendor advertising on this forum, you could just get this:
    http://www.sickbikeparts.com/catalo...ducts_id=39&osCsid=vreiovl471agi8fqvuj2kc6ra4

    You do not need both a resistor plug and a resistor wire to combat EMI though.
     
  20. Lazieboy

    Lazieboy Member

    Emi

    My MP3 player turnes it self off when too close to lawn mower and MB. Works in back pocket when mowing, dont use it when riding MB.
     
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