i did - it was set to factory settings - 7mm before it opens the valve i understand measured from the gasket but this ran too rich. so i brutalised it much lower and the idle was a little less smokey but theres a lot of judder and missing beats under power - presumably from lack of fuel.
that the black smoke is still there and it is happiest with the mixture fully tighened i'm thinking more fundamental problems.
i'm moving house at the moment so i'll take the carb off again perhaps tomorrow and have another play but theres a definate clinking noise (top end) now so maybe this engine has given up.
i'll re-check the float when i take the carb off.
cheers
toby