overheating

Any idears 115 yamaha 4 stroke less than 10 hrs run time running on ears from bottom at 12-1300 rpm in yard overheats alarm goes on. Shut down would not restart for 20 min.
Run other 115 2 stroke yami 5x plus as much. Both are run along exact same route. We have only 2 narrow channels. Flush with same hose ears ect. Max on water run speed 25 mph 1/2 plus NO WAKE ZONES Beats me??? Idears

[jergofish]

It sounds like you need to replace your impeller.

[Putershark]

Either impeller or sticking Thermostat. I would first try flushing the engine for 10 min or so by using the flushing port making sure the all the drains are clear and then try again Either way, sounds like some pretty low hours to have such issues unless the engine has been sucking up a lot of sand and junk into the cooling system and if not, then I would think that a defective thermostat would be considered a warranty issue.