Diy Cdi

[cicone]

i sure hope this was the problem---test parameters are more in line, though a bad thrystor probably wouldn't show up---if it's something else i'll be a little bummed---however, the experience ranks right up there!!! this is the board prior to soldering, all pieces with the yellow cap loosely in place to
allow viewing of the rest of the board :think:

 

[canyncarvr]

This may be too little too late.......but...

Skipro is right on about flux. It IS corrosive. Organic types used in most tin/lead mixes aren't too bad but you still don't want it left on the board. 60/40 is common. It's something like 67/33 that works the best due to its eutectic characteristic, but it's hard to find. Don't worry about that part.

Isopropyl works good for removing flux. It MUST be 99% to work worth a diddle, though. 70% does more harm than good, 97% is pretty much useless. The 99% stuff may be behind the counter at your local pharmacy. They may ask what you want to use it for. I use it all the time. Use an acid brush (natural bristle) to gently wash the junk off.

There are also 'flux removal' aresols you can get from most supply houses. Be careful with it. It eats some plastics, but it works good.

Soldering generalities: Lots of heat real fast.

Not enough heat not fast enough heats up the components and damages the laminate and conductors.

Use a damp sponge to wipe your tip with before you make a connection. Use a small bit of solder to make a heat bridge between the board and lead you are soldering...flow the solder onto the joint until a filet is formed with slight concaved slopes.

'The bigger the blob..the better the job' is a well worn phrase applied to soldering that (obviously?) tells you how NOT to do it.

When you're done with a joint, coat your iron tip with solder to keep it from oxidizing before putting it back on its holder.

Yes, I was at one time a card carrying Avionic Module Repair certified tech (AMRIP). 100 lead flatpacks under a microscope kinda stuff.

 

[cicone]

been away

Never got it to work right. it ran, but not good. Most of the parts are easily identifiable, but a few caused the trouble. What is the value of the big yellow cap?? I don't know(relied on what Jag posted). The large diode by the SCR, no markings so not sure there either. And as you can see in my rebuild vs. the original, replaced what now i believe was a high speed switching diode with a regular one. The other resistors, diodes and capacitor were clearly marked. Also had to go on Jag's call on the thermister....since I bot a replacemant CDI on ebay for $30, i've abandonned the project, though I'm sure I was just a hair from success. Good luck and remember ebay. A lot of fun none the less. By the way, she still runs like a bat outa hell!

 

[cicone]

been away...P.S.

Don't make the mistake I did and tear apart what was/is likely a perfectly good CDI because I was sure the coils I was getting from Electrex were good....later it turned out they were all junk and Electrex stopped selling them. Do yourself a favor and spend $40 and get a GREAT coil from Ricky Stator. Unless you're positive the CDI is bad...and I don't know how you could be...try the new coil first and save yourself the fun/pita of figuring out the details on the diy project. My $.02 worth.

And good luck! :laugh:

 

[canyncarvr]

Not to beat too dead a horse....but....

The Electrex tirgger coils have been figgered to be junk for quite awhile. IF they run, the timing is off, kickbacks, hard starts...all sorts of hassles.

On the other hand..I have heard nothing but good things about rickystator's products.

I'm repeating what you said to make the point...again...for emphasis, even!

Cheers!

 

[03KDXHOPPER]

I didn't know CDI boards had thermistors on them... Wonder what they're doing there.... I've never torn into one (probably lucky for the CDI). A note on the capacitors--Voltage rating is important as you have noted, but equally important is the temperature rating. Go with the higher temp. The caps usually fail earlier. In the ol' tv station, engineers used to spend hours and hours upgrading the dead 85 degree caps to 105 degrees...

 

[cicone]

The thermistor alters the timing as it's temperature changes.
As the bike runs the CDI must heat up slightly in order to effect this. At least, that's my take on it. You guys have rekindled my interest in the project. Perhaps I'll make some adjustments and post on it.

 

[03KDXHOPPER]

That would make sense. I guess when I moved the CDI and removed the airbox lid, it was o.k. where I put it.

 

[tedkxkdx]

http://www.electrexworld.co.uk/htcd...-honda-kawasaki-suzuki-ktm-yamaha-1865-0.html
I have several of these and they are made in Italy as I recall. They are good units, $67, and replace the CDI and Coil. They work on all KDXs as they have a simple ignition curve.
I ran it on my kdx for several months but discontinued its use since I was using an ICAT and the icat was making it arc to ground. With original equipment it does not arc.
If I was not running an icat, this unit is the best way to go. And carrying a spare, once you already have this set up, is good insurance for the cdi or coil failure you may see on the trail.

 

[reepicheep]

Count me in... and I have an Electrical Engineering background. I've only worked professionally on the software side, but ienjoy the electronics as a hobby.

Does somebody have a schematic for the CDI? And a good high level description of what it does?

Lately, I have been playing with PIC microcontrollers. These are little 16 pin integrated circuits that cost maybe $3 each, but that actually contain a full microprocessor. They have lots of different flavors, some with 8 discrete (0 or 5v) inputs and outputs, some with analog inputs and built in A2D converters. Very cool things... like electronic duct tape.

So what does a CDI do... and maybe more interestingly, what *should* it do? I have analog inputs to work with, so I can cheaply sense temperature, airflow, RPM (off the top of my head). I can less cheaply test pressures (expensive sensors), throttle position (would need to scavange it from some other bike like a Buell), humidity (again, probably an expensive sensor). I could probably even rig up a ping sensor of some sort... though I don't know offhand how those work.

Of course, I have to get my KDX un-takenapart first... but I think I have actually reached the point where I am ready to reassemble now... there is precious little left to take apart. :nener:

 

[reepicheep]

Funny how I find my own threads...

My KDX is back together, and running funny at high RPM's. It probably is NOT the CDI, probably a bad ground or bad coil, but I'm still interested in the project, and have a brand new microcontroller programmer burning a hole in my pocket ;).

How about a replacement CDI module that could sense temperature, and perhaps even have buttons for setting altitude and octane? And that varies with RPM? And custom configurable ignition curves? Heck, maybe even a servo controlled KIPS that also detects throttle position.

I can handle the electronics side, but don't have anywhere near the engine knowledge and experience.

Heck, maybe I'll create a PIC device that piggybacks the stock unit and builds a map of what stock actually does...

 

[mudpack]

Now, THAT sounds interesting, 'cheap.

 

[Porkchop]

reepicheep, Pal,.... you're too damn smart for your own good, you have my respect.
keep up the good work, it's very interesting to follow. Best Regards, Porkchop...