No Spark...Wiring CDI/Mag/Kill Switch Mess

MrLarkins

HS Math Teacher
Jun 17, 2008
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my cdi (I assume that's the little black box) has one black and one blue...and I connected that black to the motor black and that blue to the motor blue...my kill switch has a black and a red and I grounded the black to the frame and connected the red to the white. and my bike went 300 miles with a working kill switch

now, did this 'fry' my mag or cdi?
 

Jakylpops

New Member
Jul 10, 2008
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I'm not sure, but it is a possibility. That's why I never recommend doing the "white wire kill switch" method.
When you interrupt the CDI circuit with the normal kill switch setup, you are completely rerouting all electricity away from the CDI into the bike frame, so there is no more spark for the engine.
On the other hand, when you stop the engine by shorting out the white wire, the CDI circuit is still in contact and trying to fire the engine, but there is a second circuit formed by the white wire that is now drawing so much electricity that the engine stops running because the CDI cannot draw ENOUGH current to keep firing. I'm not sure exactly how delicate the CDI and magneto are, but I DO know that low voltage is almost as bad for electronic components as too much.
 

MrLarkins

HS Math Teacher
Jun 17, 2008
487
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Arkansas
soo...how should it be wired?

I have a black and red from my kill switch.
I have a black , blue, and white from my motor.
I have a black and blue from my CDI.

Do I do the following?
{black kill switch wire to bicycle frame}
{red kill switch to blue motor}
{black CDI to black motor}
{blue CDI to blue motor}
?
?
that puts the red kill switch and blue CDI BOTH to blue motor...is that right? and the white wire dangles to nothing?
{re
 

Pablo

Master Bike Builder & Forum Sponsor
Dec 28, 2007
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www.sickbikeparts.com
my cdi (I assume that's the little black box) has one black and one blue...and I connected that black to the motor black and that blue to the motor blue...my kill switch has a black and a red and I grounded the black to the frame and connected the red to the white. and my bike went 300 miles with a working kill switch

now, did this 'fry' my mag or cdi?
This is how I am hooked up. This shouldn't destroy anything....who said it will?
 

MrLarkins

HS Math Teacher
Jun 17, 2008
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Arkansas
This is how I am hooked up. This shouldn't destroy anything....who said it will?
noone...but I'm just trying to figure out why my bike all of the sudden won't spark...

I was just be-boppin' along and it died...now there's no spark.

my first thought was water damaged something...but that turned out false...now I'm checking my wiring.
 

Jakylpops

New Member
Jul 10, 2008
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first thing disconnect the kill switch from everything and make sure white wire is not grounding on anything, try to get the engine to fire with just the CDI connected "blue to blue, black to black" and nothing else...still no spark??

check the ignition wire, it just twists into the CDI hole on a little screw that sticks up, same with the sparkplug boot on my engine, make sure those connections are tight and making contact with the ignition wire. If none of this works I guess the next step is open the engine and check the magneto for bad connections or burnt wires, connect a voltmeter to the wiring and turn the engine over to see if it's putting out any voltage...etc.
 

Tj Bunch

New Member
Jun 18, 2008
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Is the mag more prone to burn than the CDI? I would think The CDI would go first, I'm no expert but mine i can't get a spark from anything never even fired engine yet everything tight trying to find what problem is.
 

MrLarkins

HS Math Teacher
Jun 17, 2008
487
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Arkansas
how do i test my mag and CDI

be VERY specific please...what needs to be connected, what needs to not be connected, where do i touch the black and red probes from ohmeter?
 

MrLarkins

HS Math Teacher
Jun 17, 2008
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ok, so i disconnected all wiring...
then I took the CDI and my Ohmeter and stuck the red sensor in the spark plug cap and the black sensor on the blue wire (the black wire I grounded to the frame) and my meter read 1.717 M(ohm's)

when I switched the red and black sensor, the meter just slowly climbed to 30 then read O.L.

is it supposed to be 1.717? the fact that I am getting a reading, does this mean my CDI is good?
 

Pablo

Master Bike Builder & Forum Sponsor
Dec 28, 2007
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CDI pack GOOD Mine
Black to Blue 1150kΩ 7.6 meg Ω
Black to Plug 2.6kΩ 2.17K Ω
Blue to Plug 1150kΩ OPEN


Magneto
Blue to White 327Ω 349Ω
Black to Blue 327Ω 347Ω
Black to White 2.1Ω 2.1Ω
Black to Gnd 0Ω 0.3Ω
Blue to Gnd 327Ω 347Ω
White to Gnd 2.1Ω 2.3Ω
Sounds about right!!
 

jasonh

New Member
Jun 23, 2008
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man, I got nowhere near those numbers last night. I'll have to try again with a different multimeter (if I can find it) and write them down...
 

Tj Bunch

New Member
Jun 18, 2008
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Mr.L and Pablo thank you very much we have a bad CDI I ordered one from Mr. Dax Hopefully will be here soon.
 

Pablo

Master Bike Builder & Forum Sponsor
Dec 28, 2007
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man, I got nowhere near those numbers last night. I'll have to try again with a different multimeter (if I can find it) and write them down...

I don't follow? Just remember you will get differences by reversing the leads due to diodes.....don't sweat so much a reading difference 1.2 Megohms vs 1.7 meg....or in the other direction....that it's open.....that said I don't remember the slow climb to 30 ohms and going open...
 

jasonh

New Member
Jun 23, 2008
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No I was getting like 1200 instead of 327 and stuff. Like I said, I'll have to verify tonight if I can find my other multimeter.
 

Tj Bunch

New Member
Jun 18, 2008
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Ok Guys I hope this makes sense:

Blue wire to Plug.....1.89k
blk lead on blue red on plug.

Blue wire to plug reversed 40K then OL
red on blue wire black on plug end


Balck To Blue Open
blk lead red

red lead blk 1.88K

Black wire black lead red to plug end 9.32k

Black wire Red lead black lead to plug 9.42K

I think that makes sense (at least to me it does) But then again I answer the little voices I hear........:)
 

jasonh

New Member
Jun 23, 2008
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ok I figured out what was going on last night and why my readings were funky, and I'm actually surprised by the results. I was getting funky readings because of the way I was pressing the leads to the wires - with my fingers. Looks like I was reading my body resistance, lol.

CDI:
plug end to black: 2.5k ohm
blue to black: 0.8m Ohm
plug to blue: 0.8m Ohm
the other way: no reading

Only discrepancy was when I had my multimeter on "2M" it read 0.8, which should be 800k. When I put it in "200K" mode it read 138k. Weird.

magneto:
blue (mine is green) to white: no reading
blue to black: no reading
white to black: no reading.

So this would point to bad magneto, not CDI like I thought. I took an VAC reading off the green to black wires, and got about 2v AC just spinning the tire by hand. I couldn't get a reading off the white wire, even though last night I swear I saw 4vAC

edit: ok I think I'm off on how I wrote the CDI stuff down, but I think it's good.
 
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MrLarkins

HS Math Teacher
Jun 17, 2008
487
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Arkansas
well, I just said &%@!# it and bought a new CDI...if that doesn't fix the problem, I'll buy a new Magneto

I am tired of trying to figure out if mine is good or bad