Massive Electromagnetic interference from Magneto or CDI ?

relaxxx

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Joined
May 2, 2008
Messages
96
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!
 

relaxxx

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Joined
May 2, 2008
Messages
96
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.
 

relaxxx

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Joined
May 2, 2008
Messages
96
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.
 

datz510

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Joined
May 9, 2008
Messages
204
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.
 

adamtheha

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Joined
Apr 28, 2008
Messages
72
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.
 

jared3377

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Joined
Mar 26, 2008
Messages
213
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...

Arrrggghhh!:censored::censored::censored:
 

eljefino

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Apr 13, 2008
Messages
249
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.
 

relaxxx

Member
Joined
May 2, 2008
Messages
96
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.
 
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