Ignition Breakthrough/secret of the white wire

Tohri

New Member
Aug 28, 2010
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People's Republik of Massachusetts
okay, so a month ago I bought a puch cdi high rpm box off treatland, to rebuild my aging Star Fire. Just today I had a revelation on how to get it to work, and in retrospect, it's bloody simple and I shoulda realized it sooner.

The wires coming off that box are Black: Kill, Black/white Ground, Red: Hot off magneto, and white, which is the hall sensor wire.
HT motors have a black, blue, and white. The puch CDI wires up straight to a HT magneto, Black to Black/white, Blue to red, and White to white.

Yep, that's right. The white wire does serve a purpose. The Puch CDI is a much nicer unit, though the timing in the low end seems like it might be somewhat retarded. An adjustable timing magnet would be ideal for this mod.
 

rohmell

Active Member
Jun 2, 2010
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New York
Have you tried reversing the blue and white wires from the engine?
I would think that the function of the white wire would be more of a 'hot' and the blue serving as the trigger function.
 

DuctTapedGoat

Active Member
Dec 20, 2010
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Nampa Idaho
It's purpose is twofold.

The first is to check it on the tach.

The second is to run as an accessory wire to power <7v electrical accessories.
 

Tohri

New Member
Aug 28, 2010
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People's Republik of Massachusetts
It seems to be working fine as a pickup wire for this moped CDI as well. I toyed with the idea of getting a standalone pickup, but that may be over-engineering a solution based on how small our Magnetos are. I would imagine there's a reason most mopeds have an inside out magneto arrangment, probably to get more precise timing on the hall pickup for TDC.
 

happycheapskate

New Member
Nov 26, 2009
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Rockwall TX
I have been using the white wire to power a head light and LED tail light since I built the bike. Good to hear you can use a Puch CDI. Good job. I've heard of people substituting a Puch cylinder and head on Happytimes. That is interesting of hearing you hooked a tachometer to the white wire. Did you use a digital one or old fashioned one? I saw some digital tach/hour meters for about $30, that run from a wire wrapped on the spark plug where the boot slips on, and to the frame/ground.
 

Procratinathan

New Member
Sep 17, 2012
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St. Louis, Mo
My HT didn't come with a blue wire on the magneto. Is this a manufacturer mistake or do some come that way? Anyway, I can't get it to start and I think this may be the problem. lil help!
 

bigbutterbean

New Member
Jan 31, 2011
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Lebanon, PA
I also run a headlight on the white wire, it is custom made with a built-in voltage regulator. I got it from wonderful creations on ebay. It works great, its 270 lumens and reflects off of traffic signs several hundred feet away. I dont do much night riding, and this light is plenty bright enough to run to walmart or the convenience store if needed. There really is no secret to the white wire, it is actually meant to run an accessory. I think what people miss is the idea that you need regulation. Why do you think scooters use regulator/rectifiers in their charging circuit? because they charge the battery off the magneto. Same for mopeds. Its not a secret, just something most people dont realize. The white wire can also be used to wire a kill switch. I have run this way in the past, but this time I wired my own on/off switch to the cdi so I could run my headlight on the white wire.
 

Goat Herder

Gutter Rider
Apr 28, 2008
6,248
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N.M.
When I ran a light off of my white wire I just continued to use the white wire for the kill switch too as I had done for ever before without a light.. Never hurt a thing. There is not any amperage in this circuit so nothing can burn up. I mean if there were enough amperage there then a big ol 1000 lum light would be in short order lol.
 

bigbutterbean

New Member
Jan 31, 2011
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Lebanon, PA
When I ran a light off of my white wire I just continued to use the white wire for the kill switch too as I had done for ever before without a light.. Never hurt a thing. There is not any amperage in this circuit so nothing can burn up. I mean if there were enough amperage there then a big ol 1000 lum light would be in short order lol.
There isnt much in this circuit, but magneto-driven circuits are inconsistent by nature, being controlled by the rpm's of the engine. Regulation is necessary to protect any equipment that is powered by the white wire. I am even considering installing a rectifier between my engine and my headlight, which already has a built-in regulator. Even if regulation/rectification weren't absolutely necessary, it doesnt hurt anything. But the voltage in the white wire does spike, and it doesnt take much to overload a circuit that isnt built to handle it. I paid $22 for a 270 lumen with a built-in voltage regulator, and that is much less expensive than even some battery-operated bicycle headlights.