Few things are more frustrating than pulling fruitlessly on the start cord of stubborn outboard, or paddling your dinghy (and the $1,000 outboard strapped to its stern) back to your boat. The gradual shift away from two-stroke engines to the more durable four-stroke variety has reduced the liklihood of these moments. But the four-stroke portable engines (December 1 and March 1, 2003) we’ve tested over the last three years 4- and 8-horsepower models are big and heavy. The 8-horsepower engines, which can exceed 80 pounds, can’t even be considered truly “portable.” The 4-horsepower models (about 55 pounds) are easier on the back, but it’s still no fun to wrestle these…