Water intake

Where does the water enter on a 1980 -1989 4 stroke Honda 100 10hp. motor.
Where do you hook the desalter up at?

There is a little brass screen (that may have been painted over by now) under the rear of the cavitation plate. There is no "flush port" per se'. And, even if there was, I advise not to use them but to put any cleaning "solution" through the engine by running it in a bucket. If you take the prop off, you can run a fairly concentrated form of whatever you have in mind through the cooling system from a 2.5 gallon or larger bucket and then rinse by placing the motor in a trash can full of water and running it again.

There is a product called PRESTONE SUPER RADIATOR CLEANER that removes deposits fairly well using this method. You just need to be VERY careful not to overheat the outboard since the volume of liquid you are dealing with is very small. It is a time consuming and tedious task. And, if the outboard is really crusted up bad, I know of nothing that works all that well.