After a few week of breaking parts, (Crank shaft then gearbox), I am back on my tuning mission.
My Genny seems to be running fine power wise but its still over heating and then cutting out after 3-4 mins and 180C (356F) with the body off!!!!

That was with the base settings of flush on LSN and 3.5 turns out on HSN.
I tried richening it up HSN 1/4 turn but still cuts out maybe a little later.
Then another 1/4 turn richer, again I get a little longer, but I could hear and see it was not running well and struggled to pick up revs.
So then I tried to lean it out 1/4 turn from where I started, (Base setting), and it flew, even shifting into second during the first 1sec of wheel spin but the temperature was really rising fast. At this point I was out of fuel so game over for the day. :-(

I know an air leak has been suggested, but during my rebuilds I stripped the entire engine and carb and found the carb was quite well seated.
I did not try sealing with Vaseline as I though it was a tight enough fit not to need it.

Maybe I was wrong, but it must be some air leak to be giving me this much trouble.

I am using 25% fuel and an A3 OS plug.

Any suggestions please.