Thanks , I will refit the carby and try the pump test have removed the old gasket which fell apart , reading on other forums it seems to be a common problem , if the bowls are leaking engine runs lean on those cylinders resulting in rough running , apparently if both are leaking engine runs smoother but lacks power , I will check the data , the map gauge stops at 40 , when it passes 37 it starts to die . If I leave the bowl off and hold the float leaver up then turn the pump on would that should show if the needle and seat is leaking.