looking for good lower end for testing custom Cdi units

GoldenMotor.com

moosinatrix

New Member
Sep 2, 2009
124
0
0
Houston, TX
Hi I'm building custom Cdi units for use with the ht and most bikes, scooter s and atvs. I currently am in need of a bottom end in good shape that i can use to test my Cdi and dial it in.
My first model will be a simple box with 3 factory presets (fuel-saver, low-end torque/hill-climb, and top speed) for use with a wide variety of ignition coils.

From there i how to evolve it to a fully table Cdi with 5 programmable presets. Tunable via android/i phone app, and eventually i will offer a mini programming computer that will allow for full analysis and tunability on the go.

Comments and suggestions welcome
If any one has a bottom end to donate, sale, our trade for a box, let me know.
 

crassius

Well-Known Member
Sep 30, 2012
4,032
158
63
USA
I made a nice one with timing marks out of half a crank & half a case from a bad bottom end - with a head bolted to it that had the spark plug threads chewed up.

not really necessary to use good parts on these
 

rohmell

Active Member
Jun 2, 2010
1,531
6
38
New York
We have been experimenting with an Arduino-based CDI controller, is yours based on Atmel, or maybe PIC, or FPGA?
 

moosinatrix

New Member
Sep 2, 2009
124
0
0
Houston, TX
Rohmell, im not gonna lie i haven't made it that far yet. I'm still building the fist unit and then i have to test it and tweak it until i have the 3curves i want. I was looking at the arduino kits at fry's today. But honestly i don't know how I'm gonna do the tunable ones yet as I'm still learning. Most of the knowledge i have now comes from your roll you're own Cdi thread and bits of knowledge found through google. What spawned the tunable box was the pi rasberry mini computer. If i could get them to build me portable unit to fit these needs it would really catch the eye of the racing and performance community.
 
Last edited:

crassius

Well-Known Member
Sep 30, 2012
4,032
158
63
USA
with every three motors out of the box running significantly differently, I believe I'd still be happier using a test mount that read off a timing scale as I varied the speed of the electric motor I turned it with.

Once the CDI unit had good profiles that were selectable, seems then it might be tuned to each particular motor.

Not saying this is the only right way, but a way I've worked for several years.
 

rohmell

Active Member
Jun 2, 2010
1,531
6
38
New York
Probably the easiest to start with is the Arduino, the Nano is pretty small.

You could use a lookup table so that at a certain rpm you have a certain pwm output to the SCR, etc You could add an almost infinite number of points on the curve, limited only by Arduino's memory.

Another good thing is that you can extend the duration of the trigger to the ignition coil for extended, multiple sparks, similar to how the MSD ignitions operate.

The only negative is that you would need a battery, no self-powered option here.