I have a 2000 Yamaha 115 V4 2 stroke carbed 50:1 premix that keeps sounding the temp alarm whenever I exceed 4500 rpm after about 20 seconds of running at that range. If I stay below 4500 rpm, then no alarm sounds. In May of this year I had my heads cleaned and gaskets replaced after hearing the same siren. Problem was a leak in the head gasket letting air into heads. I have not had the problem since then until now. I have continued to freshwater flush after every use since then so I am hoping the heads are not gunked up again. Since the issue has come back I have changed the entire water pump kit and housing and the entire pressure relief valve (spring, both gaskets, and plastic valve). Yet I am still getting the same alarm, but he engine is not running hot. My next thought was to change my thermostats, thermo gaskets, and the thermo switch assemblys. Or is there some thing I am missing? Should I change all of these things I mentioned? I priced all of them for $130 at my yamaha dealer. Any help is appreciated. Thanks!
