This report documents the basic evaporative emission assumptions and calculations currently used in EPAs draft NONROAD2004 emissions model. This includes diurnal and hot soak evaporative emissions as well as crankcase emissions, running losses, and resting losses. An appendix also has been included with this report that contains the previous version of this technical report. Separate reports from the EPA Nonroad Engine Emissions Modeling Team address refueling emissions and adjustments of basic evaporative emissions for different ambient temperatures and fuel volatilities. These technical reports are provided to allow better understanding of the appropriate uses and limitations of the modeling results, and to allow informed comment on the modeling methodology. Comments are encouraged concerning other possible modeling approaches and any newer test data that may be available.