Hello yes tried turning HSN further counter clockwise (richen) but no diff. Engine is not being starved of fuel until has built up some heat (after approx 5 min running at full throttle). Cooling head has good water flow, so that can not be the problem.
Could it be that it is actually too rich and it is actually bogging down at full throttle rather than running lean. Will try and get actual head temp readings and also try adjusting HSN is opposite direction (lean).
This problem has got me stumped as engine runs great until it builds up some heat. Let it cool down start again and runs fine once more until heat builds up again.
Have an electric pump, might connect it up to cooler head and do some test runs to see if head runs cooler and stops engine cutting out. But I guess I need to first get hold of a digital temp reader.