1995 Yamaha 130 2 stroke overheat/water pressure?

[ChippRiverRat]

I would like to thank you all in advance for any insight given. i have a 1995 yamaha 130 2 stroke i have completely rebuilt the powerhead on(all 4 pistons/rings de-glazed all cylinders, new bearings and seals, new gaskets, cleaned water jackets, washed block after honing, cleaned heads). i have also changed the impeller. it starts up and runs great(have 20 hours now) but when i rev past half throttle and get going above 32mph on a light 18ft welded skiff i get the temp alarm. i also have brand new temp sensors, thermostats and i have made sure the popit valve was not sticking. it seems like when i rev past a certain RPM my tell tale loses pressure and is not a completely solid stream anymore. i slow down to idle and its right back to a solid stream and within 20 seconds the alarm stops. it is not the oil alarm as the oil alarm and fill work exceptionally well. i am a month into this rebuild and this is all that is haunting me! it runs allday if i stay below 32MPH once i hit 32 it drops water pressure and overheats. :grumpy: Thanks!

 

[99yam40]

sounds like it is sucking air into the water pump.
maybe dropping motor a hole or looking for something disturbing water to the water pick up