And the winner is Keith Page!!! Thanks Keith. I tried everything else conceivable as discussed in previous posts but the high temps remained until I changed to the larger radiators - thanks for the lend of your radiators Riley, much appreciated.
The 6200RPM max issue is still current though. I tried all ideas put forward, checked the carbies (simple concept aren't they?) including pulling all jets and needles. All is as it should be with 165 main jets, needles under the white plastic spring cups, and the slides operating through the full range and in syncro with one another. I think I might have to accept defeat on this one:see no evil:Maj Millard says if the carbies are correct then look elsewhere - meaning the propeller, and has been suggested, I could source a known propeller to check what that would do on my setup. I'll see....
Thanks everyone for your contribution, I'm gonna let the situation sit for a while now, and enjoy a bit of flying without too much tinkering. Although I need to acquire the larger radiator assembly as the one I used this weekend is on loan from the very generous Riley. Thanks again Riley, I appreciate your help and good humour in allowing me to use your radiators for this little diagnosis exercise.
Pud