Massive Electromagnetic interference from Magneto or CDI ?

Discussion in '2-Stroke Engines' started by relaxxx, May 23, 2008.

  1. relaxxx

    relaxxx Member

    I thought my digital Speedometer was junk because it was always going crazy and resetting. I noticed it only did this when the motor was running and I thought it was the vibration affecting the button cell battery connection.

    It got worse after I added a toggle kill switch after reading about how the throttle kill switch can damage the magneto. I decided to take my multimeter and see if the motor running was inducing a voltage in the speedometer wires somehow. As soon as my meter got within two feet of my idling motor the display went completely berserk just like my speedometer.

    I have never seen anything that wreaked such electronic havoc! Now as I consider how I might shield my speedometer, another thought crosses my mind, is this dangerous to my body? I've heard of cell phones causing brain tumors and cell phones don't scramble a multimeter from 2 feet!

  2. relaxxx

    relaxxx Member

    I don't think ferrite filters are going to help as the speedometer scrambles even if it's not connected. Plus that doesn't filter myself or anything else from this nasty EMI. I think I'm going to try wrapping the wires and CDI in aluminum tape and a grounding wire. I'm just wondering if I need to do the spark plug wire too. I'll wrap the CDI wires first and test with my meter.
  3. relaxxx

    relaxxx Member

    Well everything I tried was a miserable failure!

    I ended up scrapping any kill switch altogether. I shortened the CDI and spark plug wires by moving the CDI. I covered all wires and CDI in aluminum tape. I found a ferrite donut from a power supply and wrapped the Speedometer wire around, didn't help at all. I even wrapped the speedo cable in aluminum tape, no difference!

    I decided to see what other devices were affected by this motors EMI/EMP. My fist pick was a LCD tetris game. As I brought it near the motor I expected to see the LCD display scramble like my multimeter. Instead it died within a split second of being withing about a foot from the motor! It is stone dead, cooked, fried, no power, no nothing, junked!!!

    If anyone thinks EMP's killing electronics is science fiction, I have now seen it first hand, from my 80cc 2-stroke!!!! Needless to say I did not try anything else.

    I am really not happy about this. I work in technology. I planned on riding this to work sometimes carrying sensitive electronics. Having electronics anywhere near this thing is not looking good.
  4. datz510

    datz510 Member

    Mabye try retrofitting a shielded spark plug wire. From what I understand, these ignitions have unshielded wire going to the plug which would definitely cause interference.
  5. Might also try a resistor plug. That is what they use in cars nowadays to cut interference I believe.
  6. adamtheha

    adamtheha Member

    Are you kidding man? That's crazy, I never knew there was so much energy coming from this thing! I don't want to be exposed to that! I might have to look into it a bit more.
  7. jared3377

    jared3377 Member

    Myself, I haven't found a solution...

    I haven't been at this MB thing too long, but I'm ready to give up on digital speedos. The last speedo I bought was a wireless-Cateye that cost me $30; it worked for a while but went kaput, and I don't know anymore. I've even tried the ferrite core thing--put about three of them on mine and it helped but the speedo still reset every so often.

    I really like the digitalness of it all and don't really want to go to analog, but I can't see any other way--and unfortunately the analogs go wacko after a few hundred miles too because of the vibration (and sometimes they don't register the speed above a certain mph...

    I feel your frustration, and please let me know if you find a solution... I've heard some folks on this site that have no problems whatsoever, yet I've had nothing but trouble and really believe it is the Electro Magnetic Interference...

  8. eljefino

    eljefino Member

    I've heard of the fuzz knowing a car was hot rodded with non-stock ignition by the buzz in their police radios. Just something to think about.
  9. relaxxx

    relaxxx Member

    A resistor spark plug or cable is supposed to reduce EMI but also will reduce performance. Since I already have my CDI , plug cable covered in hard to remove tape I'm going to try adding a steel shield over the CDI and plug cable. Going to cut it from old computer case metal, probably even a few more layers of it around the CDI. Aluminum tape just doesn't cut it.
  10. KiDD

    KiDD Member

    MY most favored parts of my body sit very near this EM source.
    I listen to my cellphone mp3 player while riding and I don't get any interference.
  11. relaxxx

    relaxxx Member

    My metal shield was also a huge waste of time. Did not help one bit. The only thing left for me to try is a resistance spark plug. I might just try adding a resistor in line with the cable. 3-5K ohms should do the same job.

    I'm just glad I found out before I brought my MP4 player, PDA, GPS, DS lite or anything else near the bike! Now if only I could leave my prostate home I'd feel a little better about it.
  12. stude13

    stude13 Active Member

    imagine the interference in your huevos.
  13. KiDD

    KiDD Member

    Not that I want children...
  14. BSA

    BSA Guest

    I think people are getting a bit to worried about the CDi's interference. It really isn't likely to harm your health. EM interference causes health problems under high voltage power lines ETC. Having a ham radio transmitter in the area would create more EM radiation. Are all the HAM radio enthusiasts dropping dead because of EM, or is Ham rado enthusiasts incidence of EM radiation related disease any higher than the rest of the population. I don't think so.

  15. kerf

    kerf Guest

    Just to be sure, lining your underwear with aluminum foil couldn't hurt. But it could lead to a rash.:grin:
  16. datz510

    datz510 Member

    What about trying to find a better CDI unit than what we have? There has to be other CDIs available that would be cleaner electrically as well as having better shielding.

    Personally, I only had problems with a wireless speedo. The CDI cooked that pretty quickly. I returned it and then got a cheap $9 Schwinn wired digitial speedo which has been working great for around 100 miles now. I do keep the wiring away from the CDI unit and have it run entirely on the front leading edge of my fork down to the sensor so as to maximize the shielding effect of my frame.
  17. BSA

    BSA Guest

    A good alternative to a CDi would be good old contact points, coil, and condenser, like the russian engines. It would make it easier to mess around with retarding the ignition ETC.

  18. loquin

    loquin Active Member

    There are no documented cases of health problems caused by cell phones or other electromagnetic devices (other than extremely high frequency devices like microwaves.) Nor has any testing which purported to show a link between health problems and electromagnetic devices ever been able to be reproduced by independent testing.
  19. datz510

    datz510 Member

    I looked around and there are lots of options for us for aftermarket ignitions. They aren't cheap, but if you want to have a clean ignition system and are worried about EMI and RFI from the cheap CDI ignition, they would work:

    These are made for model aircraft, so would have to be clean as far as interference goes in order to function in such a situation.
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