loudhvx, look inside

Thanks for that info. Me and my buddy had it mostly figured out today, but you added a little more info. (We're both mechanical engineers, and he just finished his masters degree)

I agree about the throttle position, especially on the BS34's. Since the carbs are vacuum operated, the slide really depends on manifold pressure. I spose I could just get a MAP sensor.

Oh, and we switched to arduino today haha. I think as far as the input goes, I just want to end up with a more or less digital pulse that I can run a count on to get RPM.

What ignition are you running? I'm sampling the rpm from the tach output on my Dyna 2000. Easy peasy.

Ahh yes, Arduino...

I just got done building a signal sampler to measure current versus time on ignition coils. It stores the values in real time, then I download them to a PC using a serial port as text, then I run the text into a Qbasic program to graph it. The hard part was learning how to write bitmap files from scratch.



This is the data I use to determine dwell requirements of various coils.

Previously, I did it using text. It's so much more telling when you see it in a graph.

I also just finished a ballistic chronograph using some scrap parts from work and an Arduino based microcontroller.



Testarossa,
I think you'd really like messing with the arduino platform of microcontrollers. It really lets you do things with software based control that would otherwise take piles of logic chips to do in hardware. I've only been messing with it for 6 months and the ideas just hit you non-stop on what you could do with it.

Excellent! I'm so glad that I responded to this thread. I had not ever heard of an Arduino before this. Just a brief bit of research on the internet has my interest. I can see the possibilities are likely endless. Thanks guys. BTW the DIY chronograph is cool. Right up my alley.

testarossa wrote: What ignition are you running? I'm sampling the rpm from the tach output on my Dyna 2000. Easy peasy.

Yeah I have a dyna-s, so none of that for me.

Arduino is cool, but if you want more power there are PIC's as well. Go to a site called sparkfun, they have lots of stuff on there at reasonable prices.

Just ordered all my diodes and whatever, this is gonna be fun!

There is one issue with the Dyna S, and that is the pulse will be very very short. As long as the datalogger can handle that everything should be fine. If not, then it may need a capacitor added to artificially increase the pulse width.

The arduino has a 20MHz clock, so it should be fine, as long as by short you don't mean less than one twenty millionth of a second.

Everything is on the way now, woot. This is gonna be a pretty slick setup. Datalogger and RFID keyless ignition all in one, for under $100. Gonna have an SD card to write the logs to too, pretty cool. I think the sensors I'm gonna run are just MAP, RPM, and AFR. Should give me enough reference to tune the thing, and no hassle making a TPS mount.

How are you planning on sampling for the MAP sensor? I had wanted to do that on my bike, and even bought the appropriate sensor, but never did anything with it. Sounds like a cool setup.

It goes into a port on the microcontroller, theres a few analog to digital converters on it. So the MAP will read from 0-5V, corresponding to certain pressures. you send that signal into the board, and in this case its a 10 bit ADC so it'll give back a value from 0-1024, in integer increments. All I need to do is have a formula in my code and it'll spit out a pressure in PSI. The AFR is the same, the Innovate MTX will output a value form 0-5V as well that I'll input to my board. I'll set all of this to report every half second or so to the log file, and I'll end up with a RPM value, with a corresponding AFR and pressure every half second. Then I'll graph it in excel for interpretation. I may go with smaller or bigger timesteps based on what I get back.