CDI questions not covered..I think..

[Mick77]

I have been trying very unsucessfully to find replacement capacitors for my CDI (91 B4 american).  I have tried everywhere I can think of but no one has the ones I need.  I managed to find two of the
47uF/35V, but the 10uF/50 is the problem.  One guy has some of them, but instead of the 105c heat rating, they are 85c rated.  Will those work?  Are we talking environmental temperature like under the seat, or are we talking about operating temp, since it looks like one is operating at 35 volts and the other at 50??  I'm lost and in need of assistance, and am kinda lost when it comes to the intricacies of circuit boards   I want to ride so bad and gas is going up again, someone help... please?

[Chris H]

Hi Mick,
The important bit is the uf rating, this should be the same no mater what. You can change the volts rating but if you go smaller than specified you may or may not get problems, its just the max V that they can run to. You can put higher values for Volts in but the cap will be phisicly bigger as the V gets bigger. Its the same with the temp, its an overall temp so if the board runs hot due to components and then the board is in a hot eviroment it all stacks up. I dont think under the seat will run 85c and while its apart you could always rebuild into a finned alloy box.

[Mick77]

  So the ONLY place in Austin that has the 85c caps just happens to be closed on saturdays... which also happens to be my only day off.  With Memorial Day on Monday, it will be Tuesday before I get the caps, and wednesday evening when I get to see if they solve my problem.  In the downtime, Chris, do you have any suggestions as to where to start on said finned alloy box?  Sounds like a really swell idea.
Thanks also for the *excellent* clarification on the cap specs, I'm sure that will help anyone else as much as it helped me.

[tomacGTi]

I ordered some caps ahwile ago from Digikey.com.

They had the correct spec caps as well as higher temp rated ones.

[Chris H]

Ive posted a picture of the best way to split your cdi box, if your careful you dont need to chop it in half, you can cut a small piece out of the box underneath where the cables go in and gently prise the box apart.




Chris

[Mick77]

.... yeah, that looks like it was a much better idea than mine.... but we live and learn i suppose .   I'm dangerous with a dremel.  Although, to my credit, I DID try and pry it from that exact spot, only to have the plastic start breaking away.  I kept hearing little cracking noises that freaked me out, so I opted for surgery.