RE: 4-STROKE engine is equivelent to what 2-stroke
Jon:
The FA-82 is a departure for Saito, it's the most "Oversquare" of the line. Where the other Saito singles are happy never getting over 10K rpm, the 82 comes alive at 10K. The FA-80 does very well on a larger plane than the FA-80 would be happy with, on a smaller faster plane the FA-82 would be the better choice.
Can't really call an equivalent for any of the 4s engines, just generalities.
Bill.