Download free of charge from http://www.rotax-aircraft-engines.com/desktopdefault.aspx/tabid-49  Click on this link, scroll down the page and in the search boxes select the engine type.  Select document type Installation Manual (Heavy).  Click on the search databse button.  A list will appear further down the page, select the appropriate document from this list - the file name (d*****) is highlighted in the 8th column - double click to open it, or right click to save it to your computer.