I am kinda new to the big motors that have jackplates and i had baught a new(too me) bass boat this spring and it has a jack plate and i was wondering how much of the motor should be out of the water and how should i set it for max speed ?right now the stabilizer is at the top of the water when i got it trimed up

The type prop, boat weight and location of water pickup in LU determine how heigh you can run the motor.  

You don't want to go high enough to make the water pressure drop below the manufactures recommended minimum.  You have to watch for that in turns also, don't want to be frying a motor.

Three blade props will normally run higher than four blades.

The deeper you run the prop the better the hole shot, the higher you run the prop (to a degree) the more speed you get.  That's why so many that want the max from their boats are switching to hydraulic jackplates.

The more bow weight you run, the more leverage you need to lift it so you have to run a little deeper.  The rake of the prop, cupping and design play a major part in what height you run.  

Key points to watch for when playing with height.

Don't let water pressure drop below min.

If boat loses lift, it's too high

If motor gains rpm without gaining speed, you're cavitating.

If motor blows out in turns, it's too high

The lower the motor the more the boat is subject to chine walk.

A lot of these can greatly improved by having the prop tuned for the boat as well, if it hasn't been already.

Just make sure you mark where it is, the previous owner may already have it dialed in and you are just re-inventing the wheel.

thanks for the info ben,where i got it now i think is a good spot ,i might not be getting max speed but it rides good  and goes a little over 60 and thats fast enough .