No thermostat?
 

I have a 2007 yamaha 70hp. 230 hrs. 2-3 years ago I had to pull the head and clean the water jacket in the head and replace the thermostat because the jacket was completely clogged. I checked today and the thermostat was gunk'ed up and rusted and the housing for it in the block was gunking up again. I cleaned it up and ran it on hose with no thermostat and it has a lot more flow. The thermostat opens supposedly at 120 degrees. I'm thinking if I run without the thermostat with more flow I won't get all this build up in the water jacket. I never run more than 4 miles one way and figure maybe put the thermostat back in the late winter when the water temp. really drops. Anyone running without a thermostat ??? Anyone know if it will hurt anything to run without one??? I know of 3 other 3 cylinder yamaha's that had this happen so it must occur often and all I can see is because of a lack of water flow thru the thermostat.

I ain't had one in my motor for the last 5 years or so.

I messed up and put in wrong place . Sorry...