Marktur
Member
Had to reset my speedo this morning 4 times on the way to work...
Massive Electromagnetic interference from Magneto or CDI ?
- Thread starter relaxxx
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Might try skinning the outer bundle of insulation off the pickup wires, and twisting them along their length. (Then tape back up.)
Each time they cross each other their radiation field collapses. When wires are going to something important like an airbag, or real close to something you don't want interference... like the compass on a ship, the wires are twisted. Your speedometer uses a hall effect sensor on the wheel to induce a current on the signal wire. The computer sees this, and counts the rotations (with the circumference you programmed... and displays a speed. Induce a current on the signal wire via radiation from other sources... and it goes bonkers.
A hall effect sensor is probably what is triggering your ignition! Great fun.
First off... Do you have a magneto, and a CDI box? Or are they an integrated unit right at the flywheel with a ground wire and a spark plug wire. As already mentioned, if its one magic black box a carbon core plug wire and resistor plug will help quite a bit. While you are at the auto parts store and grab a condenser and splice it into the ground wire too... A condenser is a capacitors... capacitors store, energy... they also absorb voltage spikes! Voltage spikes and electromagnetic radiation interference are similar beasts.
If however, your CDI box is elsewhere, and the flywheel magnets are generating current, like on an engine designed to power a light or recharge a battery. The flywheel is the Armature, and the power feed is coming off the stator. In the power wire you can put a resistor, to lower the voltage going to the CDI. Lower voltage in, lower voltage out... less voltage... less interference. (This is a cut and try method... to much resistance and it'll cut out at high RPM's.)
Wire mesh sleeves around the spark plug wire have been used in the past. They ground the sleeve to the frame... ancient car technology.
Good luck.
Each time they cross each other their radiation field collapses. When wires are going to something important like an airbag, or real close to something you don't want interference... like the compass on a ship, the wires are twisted. Your speedometer uses a hall effect sensor on the wheel to induce a current on the signal wire. The computer sees this, and counts the rotations (with the circumference you programmed... and displays a speed. Induce a current on the signal wire via radiation from other sources... and it goes bonkers.
A hall effect sensor is probably what is triggering your ignition! Great fun.
First off... Do you have a magneto, and a CDI box? Or are they an integrated unit right at the flywheel with a ground wire and a spark plug wire. As already mentioned, if its one magic black box a carbon core plug wire and resistor plug will help quite a bit. While you are at the auto parts store and grab a condenser and splice it into the ground wire too... A condenser is a capacitors... capacitors store, energy... they also absorb voltage spikes! Voltage spikes and electromagnetic radiation interference are similar beasts.
If however, your CDI box is elsewhere, and the flywheel magnets are generating current, like on an engine designed to power a light or recharge a battery. The flywheel is the Armature, and the power feed is coming off the stator. In the power wire you can put a resistor, to lower the voltage going to the CDI. Lower voltage in, lower voltage out... less voltage... less interference. (This is a cut and try method... to much resistance and it'll cut out at high RPM's.)
Wire mesh sleeves around the spark plug wire have been used in the past. They ground the sleeve to the frame... ancient car technology.
Good luck.
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Marktur
Member
First thing I need to do today is to shorten my blue wire. It's run all the way up to the handlebars because I used to use a kill switch there. I will shorten it to the minimum length needed from engine to black box. Then I'll see what happens and do things as suggested one by one.
Thanks for the input!
I'll let you know if I can make my speedo problem go away.
Thanks for the input!
I'll let you know if I can make my speedo problem go away.ok, just tried replacing the chepo wiring that runs between the sensor at the wheel and the computer on my ebay cheapy. Exactly the same issue. Strangly enough though, it appears to only be an issue when the motor starts. whilst it's running it's ok.....
KiDD
Member
Wow Zach, that is some first post. Very informative!
RdKryton
Active Member
Great reply Zach
Please stop by the Intro Forum and tell us a little about yourself. It looks like you have much to share and we need all the help we can get. lol
Jim
Please stop by the Intro Forum and tell us a little about yourself. It looks like you have much to share and we need all the help we can get. lol
Jim
jared3377
Member
My CDI/Speedo Prolems fixed...?
Well, today I gave the electronic speedo one more shot.:???: Even though I think it's still too early to tell (put 3 miles on it after installation), I have some confidence that this time might work... I've been through 2 speedos, $20 & $30 a piece, and decided to give it a go after reading another post about this.
You can see pics below, but I basically did the following:
I'll keep you posted on whether it still "freaks out" any more, as I'm crossing my fingers every time I start it for a while! In the pictures below you can see the speedo and the kind of ferrite core filter I got a while back in my first attempt to avoid speedo freak outs.
Happy Trails,
Jared
Well, today I gave the electronic speedo one more shot.:???: Even though I think it's still too early to tell (put 3 miles on it after installation), I have some confidence that this time might work...
I've been through 2 speedos, $20 & $30 a piece, and decided to give it a go after reading another post about this.You can see pics below, but I basically did the following:
- Bought a cheap "Trails End" speedo at Target ($10)
- Wrapped a layer of electrical tape around the entire speedo wire for extra insulation; ALSO wrapped elec.tape around the handlebar and fork right before attaching the speedo and sensor (for insulation, vibration, and non-slippage)
- Mounted the speedo on the RIGHT side of the handlebars this time (to keep it as far away from the CDI/Magneto area as possible)
- Attached the wire to the fork along the RIGHT side all the way down to the sensor (keeping the furthest distance from any electrical-interference)
- and, Wrapped the excess wire and through a ferrite core filter before attaching to the underside of the handlebar (below speedo)
I'll keep you posted on whether it still "freaks
out" any more, as I'm crossing my fingers every time I start it for a while! In the pictures below you can see the speedo and the kind of ferrite core filter I got a while back in my first attempt to avoid speedo freak outs.Happy Trails,
Jared
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I've been thinking about one last desperate and drastic modification:
Going to the hardware store's electrical department for some parts. Encasing the CDI in a heavy steel utility box with solid cover plate. Replace the spark plug wire completely with shielded coaxial cable with an inline 5k Ohm resistor And have the cable come out of the box inside a steel flex cable to the plug. Also going to ground the box to the motor mount bolt.
If that doesn't work I might even try replacing the Speedo cable with dual coaxial.
Going to the hardware store's electrical department for some parts. Encasing the CDI in a heavy steel utility box with solid cover plate. Replace the spark plug wire completely with shielded coaxial cable with an inline 5k Ohm resistor And have the cable come out of the box inside a steel flex cable to the plug. Also going to ground the box to the motor mount bolt.
If that doesn't work I might even try replacing the Speedo cable with dual coaxial.
KiDD
Member
Try using Cat-5 cable's twisted pairs... just my .02
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