An engine likes to run around 25-30 deg BTDC. Put something on the rear crank extension with deg marks. Remove the spark plug and spint the engine with an electric starter, use a timing light on the rear and move the flywheel around until you are sparking at 25-30 deg.
A harder way is degree the flywheel, spin it and see where you are sparking. Move the flywheel and re degree it until you are sparking at the right time.