The goal of this dissertation is to explore the methods of improving a small portable gasoline-fueled generator by increasing the efficiency and power quality and also reducing emissions. Advanced engine control strategies and optimized after-treatment systems are employed to achieve the goals. The focus of all three papers is a single-cylinder engine with a low power output which EPA classifies as a non-road spark ignition engine with a power output less than 19 kW. Engines that produce more than 19 kW in the same field can be very similar as they have the same purpose, but have much more stringent emissions standards. Emissions standards drive research and development, so great advances have been made in the higher power engine class, but this development is practically non-existent for low power output engines. Low-power engines are typically single-cylinder which adds additional complexities that must be addressed with unique solutions that higher power, multi-cylinder engines do not experience. Small portable gasoline-fueled generators use purely mechanical control systems to control all aspects of the engine and have no after-treatment to reduce emissions. Almost every other classification of engine uses sophisticated electronic control systems to control fuel injection, spark ignition, and throttle position to allow for very precise running conditions. Combined with after-treatment systems, these advanced engines produce emissions that are magnitudes lower than the small generator in this study. These low-power engines are used in a multitude of devices such as lawnmowers, handheld garden and lawn equipment, and pressure washers. There are as many of these devices in the United States as there are vehicles, so by reducing emissions in this class a very large impact can be made.