Suzuki DF6 not cooling properly?

[Tropical]

I just bought this motor, it's about a year old and has seen some reasonably heavy use.
The tell tale was barely squirting, and squirting intermittently so I changed the impeller.
Still not squirting, so I ran a wire up tell tale hole, it was clogged with salt.
Unscrewed the adjacent flushing screw (pilot hole) and also poked out a bunch of salt.
Now the telltale is squirting a steady stream, and pilot hole gushes.
But when I put my hand on the cylinder head its extremely hot after about a minute, especially on the plug side. This is after I put the pilot hole screw back in, of course.....(to the point I definitely can't keep my hand on it)
I'm wondering if there are further blockages in the water jacket, and if so how to clear them?
Other than that the motor is running great, starts on first pull, idles smooth etc.

[Slim jim]

Is the water out of the tell tale hot after a few minutes. If yes then water is going through the jacket. If not then the thermostat might be blocked or stuck.

[Tropical]

Well I spoke too soon, I went back out and ran it for a few more minutes, revved it in gear, then the tell tale stopped again. So unscrewed the pilot hole screw again, seemed clear, started it again with pilot screw off and lots of water. Then started to squirt from tell tale again.
Water temp was kind of cool, where is the thermostat on these so I can check it?
Thanks

[Slim jim]

Not sure on that, you'll need to find a workshop manual. There will be one on the net somewhere.