Books on 2-strokes... the 3 best (that I know of) are written by these guys.
Gordon Blair (a British engineer)...don't remember title.
Graham Alexander Bell (also a Brit engineer)...Titled ::2 stroke engine theory and performance (or something like that...been a long time)
Gordon Jennings (an outstanding American engineer though he never went to college) Titled..The 2-stroke Tuners Handbook
.......Sadly , Jennings died here just a few days ago... he was an outstanding 2-stroke engine researcher and engineer. Who among other things was consulted on GM's Orbital 2-stroke engine design program at it's beginning.... he told them stuff that they didn't believe (they were all 4 stroke engineers).... 2 years later they were having all the problems he told them they would...
....He also was the designer of the small 2-stroke engine made for the US Army for their small (8 HP?) radio controlled battlefront video spy plane...which were designed to fly over enemy positions while transmitting video back to base ...(while being shot at)... they were used in Desert Storm.
There are many articles on engine tuning and theory by him at this site....... http://www.macdizzy.com/2stroke.htm scroll to the bottom and look at the index of technical articles... Gordon Jennings.. a great mind!!
In a correctly running engine the charge burning is completed within less than 10 degrees of crank rotation (remembering from a long time ago).. which is looong before the exhaust port opens..which is well before the transfer ports open.. so the charge would never light the fresh intake mixture (in that case).
But exactly why it "four strokes" while too rich is a good question.
And Ron.. Tony was talking about the transfer ports, not the intake port.. the intake port is in fact wide open as the spark plug is lighting the mixture at TDC.