Looking at the O.S. 91 engine, for example, there are many different designations or model types for this engine. Surpass II with pump and without, ringed, fx, etc... Did a check on the comparison link but still find it confusing apart from the obvious (2 stroke vice 4,etc...). How does one tell what engine they require and is there a site that can explain the evolution and differences of an engine type over the years. What is the difference between a O.S. of 10 years ago compared to now? Hear the new O.S. are kind of quiet...love the sound of my four stroke Saito 80. Looking to build a Sig Four Star 60 or Goldberg Tiger and trying to determine a good engine (and the proper designation). Any help would be appreciated!
Thanks.