hey guys - thank you very much for all the help. The engine had a professional rebuild and rebore with new seals etc. it had two new reeds put in one i noticed was upside down so i have turned it over, and then the bike started. i have checked the float height and is okay. It seems when you open the throttle the engine sounds like it 4 strokes and stutters, but is fine just on tick over although it sounds like it is hunting for fuel a little bit. I wonder if these knew type carbs, which seem to use different jets to the old ones and do not even have a inlet anymore for the old style oil pumps, may not suit the TY250's? A friend said to me a delauto carb from a gasgas works okay, but i have had no experience of this?! Any more advice would be greatly accepted..
Thanks again
Brian