So while the world went crazy this year i had time to tackle one problem that i keep having, crappy CDI modules from China. I've had a few replacements die, some that run but don't run well, and others that never even worked right out of the box. The biggest problem is most of the ones coming out of China that are on eBay and other ATV parts sites are unknown as to whether they are made for AC or DC ignition systems. The Honda ATC is an AC powered ignition system, the AC from the exciter coil is fed directly to the CDI module. The only one i found that was reliable was from Dr.ATV, its a good clone, only costs $20, and i highly recommend just buying one from him if you need one and spare the trouble of buying a few until you find one that works elsewhere.
After i had another one fail on my 200ES this year i started a journey into not only being able to test them, but also build them from scratch myself. Which included de-potting a half dozen OEM and aftermarket CDI units to reverse engineer them, find out what component values were being used in them, and then design and have manufactured my own PCB for reproducing them. And that is where i am at now, the testing stage!
First thing i did was build a tester, for not only testing the CDI units but also for testing ignition coils and even spark plugs. I still have to put a couple finishing touches on it, i'm machining a threaded mount for the spark plug to screw into that will have an acrylic cover over it for safety, but for now its completely functional, and replicates the CDI firing at 1000rpm. Why 1000? So i have an even number i can make calculations from when watching the output of the CDI modules on my scope, for testing design changes like capacitors and SCR's to see how it affects the spark length and time.
Then there is the new CDI PCB i designed and built, i have tested the prototype and the spark is great! I have yet to try it on my 200ES as i am waiting for my order of potting compound to arrive so i can pot it into a box. But its looking very good!
Unlike the originals or their clones i decided to pigtail the connector, the wires may still ingress water over many years like the original potted in place connector did but it gives extra harness length, especially for the ATC200ES, to cut off the original harness connector and replace it with a new one. I suspect that the wires potted in place compared to the original connector will leave a lot less open spaces, and the epoxy should bond well to the wire insulation. Even if the model its going on has the correct rectangular connector instead of the round one i end up replacing the connector on the harness because its corroded or someone had been scraping the pins or bending them hoping for a better connection. So the pigtail on the new CDI just gives some length for everything to reach.
After i get the finishing touches on this done if anyone is interested i can share the schematic of the tester box. I had a small run of PCB's made for the tester, i could possibly build a few more boards and sell them as a partial kit, or i can just share the PCB design and the schematic. I really don't want to get into selling these, it was a lot of work building it and making it look nice in a case. At the most i might sell the PCB and components as a kit and others can take it from there. Besides those parts all that's needed is a couple small transformers and various bits like a switch and some connectors. The transformers are wired back to back to form an isolation transformer, and the PCB pulses the output to generate not only the high frequency AC to simulate the exciter coil but it also creates the pulsed AC to simulate the pickup coil. Its a pretty simple circuit, i found some examples online and tested and prototyped until i got it to where i wanted it. Uses an old school 555 timer IC, no fancy microprocessors or anything complicated. Just connect everything flip on the power and watch the plug fire!