DIY (Custom) ignition controller(TCI/CDI) for most XJ Bikes

First of all, Hello!
I am Friedrich, 19 Years old and from Germany.
I am currently an apprentice, becoming an Electrician for Devices and Systems.
I bought a cheap XJ900 58L Engine about a month ago to put it into a GoKart. Yes, it will be vastly overpowered. xD
While looking into all of the other parts I need, I found that the TCI is quite expensive (80-130€).
Reading a bit about the XJ900s ignition system I thought "That thing cannot be too complicated to build myself".
A few days later I started testing to read the VR coils and then started designing the PCB.
Within 1-2 Weeks I ordered the PCB for the project.
The PCBs arrived, but I haven't assembled them yet.
It is based on the widely available Raspberry Pi Pico microcontroller, so changing things in the firmware wont be too hard.
Parts costs are quite cheap, so I thought maybe people would be interested in buying them?


The big advantage compared to the original is, that you can create a completely custom timing advance curve. So there would be no need for those tacky, sketchy timing advance "slot hole" mods anymore.
You can also software define a rev limiter.

I have not assembled the PCBs yet, and I also still have to program most of the firmware. I am also currently rebuilding a Carburateur battery I got for relatively cheap, so I cannot test it yet.

The TCI should be compatible with probably most if not all XJ bikes, but since the Timing Rotor Plates are shaped differenly on almost all XJ Bikes, some images of the Plate, Engine codes and Model Years would be greatly appreciated.

Is there Interest in it at all, or am I just doing all of it for myself?
I am also thinking about open sourcing it when it is complete.

Any feedback will be greatly appreciated.
Greetings from Germany, Friedrich!

 

Hi @criscrafter. Welcome to the group.

That is great work you are doing.

There have been other people considering the same or similar project. Would not hurt to collaborate.

 

Hi, welcome. I bought an Arduino with the goal of doing similar to you, right now it's still in the box...
So are you embedding the raspberry pi on your board, or adding a board to the raspberry pi?

 

Most interested and may buy one in preparation for when my own TCI unit turns its toes up.

 

I sent a lengthy reply to you, but it is being witheld and needs Moderator approval.

 

Since the moderators don't seem to care about approving my message, I will post it again in two messages, only @ing one Name per message. Because I think that was the Reason for my message being widtheld...

Hey @Minimutly ,
I am using the Raspberry Pi pico which is basically a faster Arduino with more pins.
I will just use off the shelve Pi Picos and solder them onto my PCB. You can see the location on the left side of the PCB where the many pins are.
I thought about putting all the components of the Pi Pico onto my PCB, but the cost savings would be slim(0,50-1€ per TCI) and the production time and complexity would increase dramatically.

 

@Dave in Ireland That is awesome to hear!

With that, it would also be interesting what you think a fair price would be?

I will definitely keep you all updated in this thread.

Greetings from Germany, Friedrich

 

Interested in the cost of these.

 

Parts cost would be relatively low when building more of them. Probably 20€ or less.
There is also some assembly time(if done manually 1-3h each) and I want to add a 3D Printed Case.
Also, development will take quite a bit of time. Hardware development is relatively fine, Software will be more complicated.

I would think that I would maybe take 80-100€ for a complete one incl. case. Not really sure of it yet tho.

 

The improver in me (aka someone who can't leave anything alone), would say that it needs 3d to make it better, instead of a simple replacement. Load measurement using a shared, or damped inlet vacuum would really liven up the low load end of the XJs power curve...

 

That would definitely be possible, but I am not sure if or how well I am able to program it. I think it would be doable tho.
I am also not sure where you would measure the intake vacuum.
In a car engine you would measure it behind the throttle body, but since the XJs got indivitual throttle bodies in the 4 carbs, the vacuum would be kind of pulsed.
I can look into it for a V2, but for now I want to get this one working.

Edit: I am dumb and completely ignored the "shared or damped inled vacuum"

I will look into it.

 

I also thought about adding a Throttle Position Sensor, but at that point I could just go as far as adding electronic Fuel Injection by using the Throttle body of a Yamaha FZ6 which you can sometimes find for 30-60€ and just completely ditching the Carburateurs.
But that takes the project too far and also every TÜV(german MOT) inspector would instantly see it and take the bike off the street.
I have put connections on the main connector that will allow me to connect external sensors like a vacuum sensor or a throttle position sensor. They also allow me to connect a small external OLED display for diagnosis or to show the RPM very accurately.
I have also put connections for a small OLED display onto the PCB, so I can make it visible outside of the case.
I am very happy to answer any questions that come up.
I am currently moving from my old room into the attic, so I cannot work on the project currently.
What will also not help is that I am rebuilding the Carburateurs right now, so if something wont work I will not know that easily if its the Carburators, or my TCI.
Well, I guess I will see...

 

I just got around to populating one PCB, and everything I can test right now has been tested sucessfully.
I have to wait for another Raspberry Pi Pico from China, because the USB-C knockoff I have right now, has got a different pinout than the original.
Unterneath you can see one picture without the Pi Pico plugged in, and another one with it being plugged in.


I will still have to find ignition coils somewhere for cheap, because this whole thing is on a really tight budget.

Just asking again, a few pictures from the different ingition trigger plates for the different XJ Models would be really interesting and helpful.

I will update you on any news there are.
Greetings