1980
In 1980, it was a Yanmar 2QM15. This is a very durable, two cylinder, raw water cooled engine that develops a peak of fifteen horsepower, fourteen horsepower on a continuous basis. This engine came from a series that were lightweight in their day, but a good bit heavier than the engines that came after. They are legendary for their simplicity, longevity, durability, noise and vibration! Someone once told me that they were based upon an engine that pumped water on a continuous basis into rice paddies in Japan. I don't doubt it, but it could be just an amusing story.