Re: Yamaha or Suzuki/Johnson
My guess is you will find few companies willing to design a competitive 4-stroke engine from scratch without any previous experience. The tooling and design costs are much higher with the high output 4-strokes because of the higher number of moving parts and tolerances. Its cheaper to buy one from somebody who has experience. Even the Big 3 auto makers in the USA bought their small overhead cam engines from foreign automakers for years (some still do) rather than retool for the more modern engines right away, and the volume of small cars far exceeds the number of outboards sold. Suzuki, Honda, and Yamaha have years of experience producing high output 4-stroke motorcyle and auto engines in addition to direct experience with 2-stroke outboards. I am going to go out on a limb and guess that it is actually easier to design and tool a new E-tec, which is really just a new fuel induction system for a 2-stroke, than it would be to design and tool a 4-stroke of comparable output.