Investigation of hydrocarbon sources and reduction in small four-stroke spark ignition engines

The purpose of this dissertation is to understand all of the unburned hydrocarbon emission mechanisms and to determine where the best gains can be made. In-cylinder emission reduction should be maximized before assuming that catalysts are the proper solution. The results discussed throughout this dissertation will reveal that several emission reductions can be achieved through methods that are more easily applied to small utility engines. --Introduction, page 3-4