Kazafog:

Your measurement of 0.7 volts AC on the AC power pin with the CDI plugged in is wrong. You still get good voltage on this pin with the CDI disconnected. This points to the CDI being bad.

The fact that it worked for 5 minutes also suggests that the original CDI was problem, the new CDI fixed it, the new CDI then failed, and your back with the same problem.

This is a good example of why you *must* measure the stator AC ignition power with the CDI disconnected. The CDI can (and does even in normal operation) jack around the AC ignition power from the stator. Thus when there is a problem it is impossible to determine if the stator or the CDI is at fault unless you measure voltages with them disconnected from each other.

Ordering a new coil is fine, but what I really think will fix the problem is ordering a new CDI from a different source.

Armagh:

Your post was very helpful. Thanks for that.

 

armagh,

My first thought was the CDI being faulty, it seems strange to me that the volts on the power supply to the CDI would only measure at 0.7v with the CDI connected.

Does anyone have a good 5 pin CDI they can test for me.

I think its strange that I have 0 ohms between the kill switch and the power supply. The old CDI was not like this, but it didn't work, but it seems as though the cap was stuffed as I cannot measure farads across it. I can measure 0.1 micro farad on the new CDI, though.

If I use a diode test I can see 1.5v from grd (+ve) to the kill switch and 0.7v grd to the power supply pin on the old CDI, but 0.7v on both for the new one and the polarity doesn't matter. It has to be the problem. Now to see about getting it replaced free of charge. Even though the next one will probably also be garbage.

looks as though I bought a new coil for nothing.

 

thanks Lynn,

I was typing a little slow, but as usual it looks as though you are on the money.

 

kazafog, I am almost positive that cap means capacitor, but what do you mean when you use the word stuffed?

...ie , "but it seems as though the cap was stuffed as I cannot measure farads across it. I can measure 0.1 micro farad on the new CDI, though."

 

Kazafog:

Since you're trying to measure the internals of the CDI I thought I'd post the schematic of a 5 pin CDI I took apart and traced out a while ago. This is not necessarilly the same as your CDI - there may be other designs that take the same inputs, make a viable output, yet use completely different electronics inside. Yet this one seems the most common:



The [C]apacitor in the acronym [CDI] is C1. As you can see it is buried in other electronics and would be hard to measure accurately from just the external pins.

Armagh:

I think "stuffed" means "bad", "no good", "kaputt", "spat the dummy", etc. I'm not sure the origins of the term, but I hear it a lot from British and Australian correspondence.

 

that would be aussie correspondence this time around. Thanks for the schematic, it is a fairly complex circuit compared to some build it yourself CDIs I've looked at in the past few days.

Heres a link to one from silicon chip for any interested parties, its a pretty informative link.

Silicon Chip Online - Replacement CDI Module For Small Petrol Motors

 

and yes Lynn was right "bad", "kaputt" etc

 

Oh, I see. The cap was " bleeding stuffed".

Lynn Edwards knows more than just "sparks", doesn't he?.
A "bleedin" genius , he is...

 

second CDI died after 5 min also, admittedly it was from the same source but.... does anyone know a reputable source for the 5 pin CDI boxes?

Also is there anyway that the bike could have something else wrong with it which is killing the CDIs, maybe?

Any ideas would be greatly appreciated. The kids still haven't got the ride this thing and we've had it for 3 weeks or so, very annoying.

 

I don't think there are any reputable sources. They make CDIs (or whatever module) at rock bottom cut throat prices. Think about it. All those parts, assembled, tested, and delivered for $10 USD (it is the most I've ever paid for one of these). They don't want to ship bad product any more than you want to receive bad product. They lose money when they ship bad product. But their business model cant allow for extensive testing. It is too expensive. They come off the assembly line and are plugged into a fixture. They get spark - it works. Ship them. If it is going to fail after 5 minutes, they would never know.

So your source (and Armagh's) has made a bad lot of modules. And the distributors are up to their eyeballs in them. The distributors don't know. The ones they shipped last month were OK. These should be the same. Distributors lose money when customers want their money back. So they go into denial mode. The factory goes into denial mode. They can't afford to do anything but that.

Eventually the problem get fixed and the CDIs (or whatever) work again. But now another rock bottom cut throat company makes a bad batch. The first company is making good ones again. The problem has moved...

This will never change as long as people shop for rock bottom prices without regard for quality and reputation. Would you be willing to pay more (and it might be a lot more) for quality? I expect most people won't.

But for goodness sake, if you have a bad CDI, don't buy another one from the same place. They may have thousands of them (bad ones that is)!