For most gensets, simply changing the orifice and a few adjustments will allow the conversion.
Here are links with instructios and video:
http://www.thegoodsurvivalist.com/how-to-convert-your-generat ... read more
In most homes, the neccesity of new windows does not usually crack the top 3 in terms of energy efficiency improvements.
You can usually get more efficiency mileage and bang for your remodeling dollar ... read more