ok some good news, after a soak in the phosphoric acid i drained the excess and left it overnight. It did not rust but did leave some black deposits which apparently is a conversion of any remaining rust. Then i swilled it out with the acid again which left it clean, so following the advice on the real bike post earlier i washed it out with water (tap water sorry Julie!) and then dried it thoroughly with a hot air gun then swilled with diesel. put it back on bike and went for a short ride, and it does seem to be running well. Thanks to all the advice especially Ash for the suggestion of the phosphoric acid.
