Remove spark plug. Put rope in spark plug hole to block piston to prevent engine rotation , and then insert the correct hex wrench in the center of that cup and unscrew.
#3
primerbulb120
Rotate the crankshaft until the piston is at the bottom of the cylinder, then stuff it full of clean rope or clothesline through the spark plug hole. You can use a large Allen wrench to unscrew the starter clutch, or just use an adjustable wrench or a pair of channel lock pliers (which is what I'd do because I'm too lazy to spend time looking for the right size Allen wrench.
