A good read to learn about 2-stroke theory is "TWO STROKE TUNERS HANDBOOK" by Gordon Jennings. It's not in print anymore, but you can download it and print it. This book is the bible of two-stroke engine design/modification. I guarantee you that Eduardo Picco, Mario Rossi, etc... has a copy of it and refers to it on a regular basis. The book was written in the 70's and is greatly responsible for the leaps and bounds that have been made in two-stroke technology over the past 30 years. Now of course the book was written with the assumption that you were modifying your Maico 490 (it's a motorcycle) , but the principles are the same, just on a smaller scale. For anyone wanting to broaden their understanding of how these engines work it is highly reccomended.