first off welcome to the site
and sadly, there is NO way to fully be sure all Crap that went into a motor once sunk comes out ,
other than split cases and hysically clean things out!
as its NOT just water that gets in when sunk and its the crap that tends to eat parts in a motor more than the water, neither one is good in a motor, but?? getting water out is ONLY half the game here!
MANY folks , do flush with other things like diesel fuel, kerosene, and of course motor oil
but all that does is MAYBE get some stuff out, its NOT 100% by any means and what I call a gamble, some times you win, many times you don't
its just part of the game when you ride an atv like its a boat
for most folks, a few flushes are all they do and away they go, as odds are, sooner or later they will again SINK it, so they don;'t bother doing it RIGHT by tearing down motor
they just run till it needs motor work and rebuild and repeat the game
as they say, you have to PAY to PLAY
NOT what you want to hear I am sure
but honest info here and above !
a RIGHT way and then a GAMBLES way
feel; lucky LOL