Got this tip for a friend:
with the motor on the transom, I tilt it up and slip a plastic kitchen trash can underneath (with a small
line lashing the trash bin's handle back to the boat). then I drop the motor back down (bottom of the outboard now pushing the empty can into the water)... then I fill the trashbin with fresh water until it comes neutral in the water.
At this point, I disconnect the
fuel line and then start the motor (gear in neutral of couse) and let the motor run until it stalls (drawing fresh water from the trashbin and depositing the flush water from the cooling water exit back into the sea. This both clears the motor of two stroke premix as well as flushes the motor.
After the motor stalls (from lack of
fuel), I simply tilt the motor up and dump the remaining freshwater in the trashbin back in the sea ( and then store the trashbin onboard for the next trip (under the cockpit
seating).