Just to throw another spanner in this.... my preference is to concentrate on the TCI ignitions. I think it may be possible to reverse engineer them and provide a resource for repairing them. My TCI igniter failed this spring. I tried the usual repairs for it and after no success, bought a Pamco kit. I have noticed that the camshaft based advance is not as good as the old TCI. The timing is just slightly more wobbly. I would like to go back to the TCI eventually.Perhaps this suggested project needs to be broken down into a few steps:
If you can solve the Pick-up/ElectronicTiming advancer circuit then there are many choices available for cloning the ignition unit which drives the coils.
- Pick-up (Crank driven vs Cam driven - choice of sensor)
- Electronic Timing advancer
- Ignition unit to drive the coils
I suggest two options:
- XS with points could just use an off the shelf coil driver - Points only handle a few milliamps so do not need regular adjustment, but make sure your oil seal is good.
- XS with TCI could just fit a Boyer Bransden
...possibly one of the tantalum caps attached to it are bad...
.Personally, I believe the Czech make very good products, like Brno and CZ firearms,.
Sorry Paul. I meant to send a better reply, but ran out of battery juice on my tablet last night. Damn technology! Anyway my first goal is to try to understand the existing TCI modules. You have provided some interesting bits of info in that regard. I traced out the circuitry of my busted module(as best I could) and will do the same on the six wire unit. Sometimes, when you trace it all out and look at it with fresh eyes you find new clues. With those schematics and lists of substitute parts, hopefully people can repair more of their own igniters. The next step will be to map out the advance curves. I have seen some idealized curves on the internet, but can’t imagine how these crude little igniters could ever do those idealized curves. The curve you suggest seems more likely. I have some ideas on how it should/could work but nothing firm yet. Anyway, probably won’t do anything till winter. Too much good riding weather right now.Sleddog83, good idea. But we need to identify which TCI to go with. The XS650SH TCI contains a proprietary IC (Quad Comparator incorporating a mystery circuit) which is no longer available. I believe one of the later XS models has a quad package with a modern equivalent available. But then these XS TCIs have very little in the way of a timing advance ramp. It is more of a switch from idle advance to max advance at something like 1800rpm. A bit primative but still a step forward from running the bike at full advance over the entire rpm range including idle.
I think Boyer is a good choice but as you and others have pointed out a crank based trigger is usually better/more accurate than cam based. Not being a racer I was happy with the Boyer system which I believe ramps up the advance in 50rpm steps.
The XS TCIs also have a no longer available switching transistor. However there is reported to be a suitable modern alternative with good characteristics resulting in a very good spark (ST901T - used in many small modern electronic ignition systems). I have tested the ST901T and it does work.
No all the diodes are good. I am referring to c9 and c13. They are blue with a white top. No discernible writing. This is from a sk model(83). I did post a picture of this board elsewhere on this forum. They look a bit like tantalums.I wonder if the reference to Tantalum capacitors refers to the following diodes D1 - D4?:
View attachment 146415
I have never heard that name before. I remember seeing those on some of the old RADAR equipment I used to work on,( back in the days when we actually fixed things). Any idea what values these particular caps should be?We called them "Dipped Egg" tantalums.
I recall that the problem caps were yellow, or butterscotch colored.
View attachment 146453
I did come across some of this info in the past. The vision TCIs use some of the same components. Good info on darlington transistor substitutes and good general theory info on TCI systems.Maybe you guys can find some sense in these links...............some iof the links from the first link dont work any more but it does have some PDF files, for resisters and graphs, that download....
http://www.jetav8r.com/Vision/TCIRebuild/TCI_Rebuild.html
Found a link to RidersofVision.net and in Technical there is more on the TCI's and CDI's......
http://ridersofvision.net/
Under technical
http://www.jetav8r.com/Vision/IgnitionFAQ.html
... Any idea what values these particular caps should be?