Okay, my interest is with 1970's motocross bikes, so this book is excellent in terms of approach and discussion. It makes some very sensible, easily readable, tuning tips and ensures that you tackle the obvious ones first, ie easiest with best performance improvement. Lots of experience and practice shows and knowledge of 70's and 80's two-stroke racing engines is obvious.
The book is based on practical know-how and experience. It has some theory (and mathematical equations), but is also full of common sense. Great read and lots on insight