Its been a while, but I believe that the 18-27 is timed just like the 80.  There is an inspection plate on the bell housing which will swing open and expose the fly wheel.  The flywheel is marked with a timing mark which is firing position for #1 cylinder.  Make sure #1 is on compression stroke.  Line up the mag for firing position for #1 cylinder and install.  The second spot on the governor shaft is to install the pulley to drive the generator, if the optional lights are installed.  Hope this helps, or e-mail if any questions.  Terry.