I have a Merc and what I say might not apply to a Yammi, but....I would seriously hesitate before tilting the engine while flushing.Water in the cylinder once and you will cry big $$$$. If you are looking for a confirmation on how long it takes, from dry motor to when it starts peeing, then you can do the following : put some kind of tank, full of water, to cover the water pump aspiration inlet of the motor and run it like that.Pay attention to how long it takes for water to come out of the pee hole. ( you can effectively do this also in the sea, with someone starting the motor and you watching the pee-hole). Then, when you flush with the muffs, always make sure you have plenty of excess water flowing out of the muffs, and a high pressure.You might want to manually tighten the muffs a bit .Make sure they are double muffs, one ' ear' spitting water , the other plugging the water intake grid on the motor. Question: can you flush your Yammi directly from a flush port , without using the muffs?That way you can double check if the pee hole is not obstructed by sand, silt etc. CAREFUL , if and when you flush directly from the port, not to use excessive water pressure, as doing so might force water through passages in the cylinder head where you do not want it to go. CAREFUL, if the pee hole is indeed plugged up stop the motor and proceed to clean the water path to the pee hole: usually , just disconnecting the little tube to the pee hole, sand will come out. So , recapping: With MUFFS, full pressure, make sure the muffs are tight around the water ports With FLUSHING PORT, just the pressure specified ( 4 to 5 psi should do) Good luck