Sunday, December 12, 2010

Peugeot Coil Success!


After about the 4th time re-wrapping this son of a gun I finally got it to fire and damn, is this thing kickin! I'm going to re-wrap all my coils from now on. I got too carried away with the excitement of everything finally working so i completely forgot to take enough pictures but I can at least explain what happened and what i did and all that jazz.
From Puegeot coil re-wrap

So the first time, i did this pretty sloppy, twisted together wires a bunch of the connections, wound the core sloppily and fast just to see how things would work. I used the 'black' wire that was connected to the 'ground' of the coil as my new live wire coming out of the magneto, to keep the grommet. I attached the hot off the coil to the purple wire in the puegeot stator which goes to the points/condensor. I also unhooked the brown wire that goes to the little brown resistor thing... no idea what that does. The other side of the coil was grounded soldering the magnet wire to the tab. I also had to replace one of the phenolic circles that border the coil with a couple rounds cut from the top of a tupperware.

I attached an old italian 1 wire coil to the mounting tab on the swingarm- perfect fit! I ran a ground strap from the mounting bolts on the coil to the frame. I used a nut on the intake manifold but it would have been much easier to tie into the grounding strap that connects the engine to the frame (dark blue w/ spade connector). Might do this later if there are connection problems.

The first winding gave me about 4 ohms of resistance through the coil. I was shooting for a replica of the Puch coil by matching the diameter of the wire after winding- which is 24ga and gives 2 ohms. Like i said, this was a pretty sloppy winding job, so i pulled all the wire off and started again. It was a lot nicer job this time, and had me at 2.6 ohms but still not perfect and even-like.

At this point, i took a second and shored up all the connections, soldered everything together, and did a much more careful job of setting the points and flywheel position to get the right dwell, because i was worried that might be a problem. I checked and re-checked my resistances. Still no spark. I was getting frustrated because i cant afford gas to be driving a car all over for another week, so i tried putting a Puch coil in... that didn't go so good either, long story but its really not a very good solution to this problem at all, you have to drill the holes out pretty big to get the right air gap, and space it with washers, and its a pain to drill because its a laminate... plus the curvature of the core is wrong for the larger diameter flywheel on the puegeot.

So i bailed on that idea and went back to winding again. I took the wire off that gave me 2.6 ohm. This time i was very careful and went a lot more slowly and wrapped it nice and even. I also used a lot more tension to keep the wrappings tight and the wire straight. I started with the side with the tab (right hand looking at the stator) and soldered on the base of the wire. The center of the core had previously been wrapped with electrical tape, but in hindsight cloth tape like you put on hockey sticks might have been better, the electric tape is too mushy. You need to start with a very sturdy base to make sure the wire lays evenly or it will be all messed up. The ends are the hardest to keep even so be extra careful. Then i wrapped it clockwise holding the 'ground' end in my little drill holder magiggy.
From Puegeot coil re-wrap

I dont know how many wraps or how long of wire i used, sorry, i should have been paying more attention, but it ended up about 3/4" diameter. I was measuring it by the resistance.

At the end of the wrapping i slipped some shrink wrap over the hot lead and wrapped the whole shebang with a tight cover of electrical tape. The coil probably should be potted with epoxy, but seeing as this is an experiment i wanted to get it working before setting things in stone, er, epoxy.
From Puegeot coil re-wrap

Once everything was wired up perfect-o i replaced the flywheel, set the points, and spun it with a drill to see if it was sparking. Holy crap! The spark is like nothing i've ever seen on a points system. Super hot, making a sharp crack, and almost like a flame thing where it comes out of the wire. It can jump over 1/2" as opposed to the old ignition that could barely jump .016" spark plug gap.

Once i got the bike all back together ( I also had to fix my busted exhaust pipe flange) it fired up just by pushing the pedal by hand. Barely one turn over, cold.

I brought it home and rode it to work today, took a little bit of persuasion to get it to fire, what with it being 8 degrees out and all, but it lit up pretty easily and is running much, much better in the low end. The acceleration from a dead stop, especially under load, is amazing. The hill in front of my house that i couldn't get up before, i can now ride up from a dead stop.

This is an awesome mod, and if you have the patience to do it right it would be pretty easy, it took me 4x as long because i was being impatient and sloppy. I still have to hook up a tail light, brake light, and (probably) some sort of voltage regulator to get the whole system up to 12v spec after gutting the electronics, so i'll keep updating this post as things come along.


  1. very nifty. I was trying to figure out how to utilize the stock stator/coils/ etc. on my 103sp. i'm too broke to afford a new cdi set up. womp womp.

    great job!

  2. I'm going to do another one of these over holiday break, so i'll take better pictures and re-write this for clarity.

  3. I can't follow all this crazy technical electric talk :( Waiting for the step-by-step later!

  4. What does the resistance of the coil correspond to? I know you can figure out inductance by number of rows/layers of wire, but don't know what the resistance means.

  5. resistance correlates to wire length.