In SX Microcontrollers, SX/B Compiler and SX-Key Tool, Tinker wrote:

Being involved in building some hotter motorcycles etc for a while I'll just toss in my 2 cents on A/F ratio's. First part being, that varies drastically by engine design, most of the bikes I deal with would melt holes in things anywhere close to 14.7:1 so thats something to keep in mind, most 2 strokes are considerably richer than that as well as most cars at any kind of load at all.

The 12.5:1 number that John threw out is a good full throttle starting point, and be very very careful taking any gasoline engine above about 13.5 at any condition other than idle. There are a tremendous amount of calculations and variables to deal with to attempt to run something at a stoic ratio. First being what was the original engine designed for?

The project is awsome Marki, keep it going.

My 2 cents on the clock speed thing?  If the chip is stable at 75 I'd go for it. For my own applications I've stopped at 50mhz strictly due to environmental concerns. Sealed enclosure, heat build up etc etc. Keeping in mind Marki's very realistic 14,000 RPM goal... The more clock the better I say, at 20 there's a very sneaky suspicion that its going to run out of power fast trying to do real time processing..

14,000 RPM is 233 rev per second, or 4.29ms per revolution, in end result on each revolution on a 2 cylinder, you need to fire the ignition, control dwell, timing advance, and fire the fuel injector as well as control injector duty cycle. Maybe everything doesnt have to be recalculated for every revolution but odds are the full sensor array will have to be read, stored, and values redone more often than most people think. Under full accel any delay in doing true real time calculations will result in a drift in the air fuel at minimum. So what is acceptable drift? How fast will it drift? What is the rate of accelleration? 

Marki, huge props on this one. Its always been beyond my level of bravery and yours is already up and running!

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