Just purchased 2 Optima 900 CCA Marine Batteries, installed if I go to full throttle on the Riptide Saltwater 80 the throttle gets really hot as well as the cord. Is their a maximum amperage rating that you can use so you don't damage the unit.

Maybe the pin is sheated on the prop...or something is caught in it..
check the prop.

check make sure its not wired backwards to batteries

Many times on the battery lead, actually the part that tightens to the battery, has a circuit breaker. You will notice a small reset button on each positive lead....of course there are two for a 24v system. Reset each one!

what handle, there is no handle.

max is 56amps on 24v system

1. possibly a broken connection to the motor where the propeller is located. 2. Also could be a bad motor. 3. Look for a fuse location for a possible blown fuse to the motor. 4. motor brushes could be the problem.

possiblty a shorted power transister in the speed controller.

I have minnkota riptide i had to take the handle off and a little spring & white plastic piece poped out of the handle i just wanted to see where it goes

Parts can be purchased from this dealer...There are schematics on the site for review....
http://www.northlandmarine.com/MinnKotaQuickRef.htm

If it is a bow mount model, then you basically need a bow mount bracket attached to the bow of your boat. If one didn't come with the outboard, you will have to buy one from the same manufacturer or an after-market one suitable for your boat. If in doubt, consult the local boating or marine store or wherever you purchased the motor or the bracket from.