Derbi CDI installation step-by-step
June 11, 2009, 3:58 am
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So derbi owners have pretty much always only had one ignition choice: stock (points or for some the electronic ignition found on the ds50). Now I’m going to show how the CDI treats sells can be adapted to fit your derbi. This is going to be for piston port bikes, but the same procedure will work for pyramid reeds, and should work for flat reed as well, just ignore the coil flip.

Buy CDI here

Ok, so you got your CDI which has a new stator, flywheel, cdi box/coil and maybe a regulator. This was on my race bike, so I pulled the lighting coil just to clean up the wiring a tad. Your going to need a dremmel or files to slightly modify the stator, a m4 tap and appropriate sized drill bit, and maybe some lock-tight.

The first obvious complication is mounting the stator in place of the old one. You’ll notice the diameter is a tad smaller, and you want it centered as well as possible for the best pickup to be sent to the box. So you are going to have to slightly enlarge the center hole (towards the lighting coil). Next you need to enlarge one of the screw holes so you can use two screws to hold the stator to your cases. I ended up using 2 screws, one just to the right side of the main ignition coil, and the one right above the lighting coil (see photo). The one above the lighting coil needs to be enlarged about 5mm to the left. You may need to pull the lighting coil off to mount the stator to your cases, but you can just re-install it once mounted.

Basically the lower screw is tightened and the plate shifted as far counterclockwise as you can get, so just enlarge the hole above the lighting coil so you can rotate the stator to that position and screw in the bolt. This position (with the pickup relocated) got me right at 1.8 mm btdc)

So now the stator is lined up, but the case is getting in the way of you wires out of the stator. You need to dremmel open the little supports for the crank bearings/seals (see photo). I believe you will only need to open up 2, the one just above the lower screw hole, and the one to the left of it.

With those done, the stator will just bolt on with the cables out of the way. You will still need to relocate the pickup (tap and locktight) and possible flip your ignition coil. I am running a za50 cdi box (counterclockwise spin), and had to flip my coil (note the position of the blue wire from the coil to see which direction). If you have an e50 box, I don’t think you will need to flip it, but always check with a timing light to make sure it sparks through the range.

So thats it, just a little modifications and this wonderful and cheap cdi works, and quite well at that. It really brought my bike to life, and is a nice departure from points. Now your only issue is figuring out where to mount the cdi box and coil. Also note, on one of our 5 piston port derbis, the cases were super weird with extra large supports for the crank bearings, thus not allowing the flywheel to fit inside. You could likely dremmel everything out, but I’d be careful.


2 Comments so far
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Cool blogpost, did not thought reading it would be so interesting when I read the title with link!!

Comment by loyakeTholo

Awesome write up.

I used this method to wire up my pport.

I actually had one of the mutant cases that have little strips of aluminum blocking the flywheel.

It was a lot of dremeling but I did manage to get the flywheel on without making contact.

Comment by Tate

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