Progress report:

I have my Ryobi 33 just about broken in now, a CDI ignition from c_moore, and a coil/spark lead from C&H. I have interfaced it to a PIC 16F84 chip, which I programmed to demonstrate that the PIC could control the spark. After I get my Ryobi back from my friend who is machining down the magneto/flywheel to give adequate prop adapter support I will be embarking on demonstrating a computer controlled spark advance. I've upgraded to a PIC 16F628 chip since the old 84 chip is being phased out. The 628 costs less, about $4.00 from Mouser Electronics, and has twice the programming capability. It also has analog input capability which could be used for future expansion such as for engine temp input.

To give him a plug, the stuff I've gotten from c_moore is great and it does the job. He has also been most helpful.

My first integrated test run should be within a week. I'll keep you all posted as to the results.