Simon
The solution was simple in the end and all down to the idiot I trusted with the carburettor. Due to circumstances you are aware of and the fact that I don't bend too well these days I have been unable to give it the attention it deserved. Yesterday the Sun shone so the day had come. What was occurring was when I rode it I could get to about 30 and it gasped when trying to go faster. The "engineer" had raised the float level too high causing some petrol to flow but not enough to go anywhere with confidence. Simply when you know and fix it, a bugge* when you don't or haven't the time to look.
Hope fully it will behave itself in the future and I can learn to ride it properly soon.
Den