thanks guys,i have checked all hoses several times,and run engine and checked with propane around manfold and carb,no difference in rpm,will try carb cleaner and check float levels,could leak be on internal flanges inside engine, [taken manifold off and checked all mating flanges and fitted new gaskets all ok],but i checked this by blocking breather and seeing if it sucked on my hand when covering the oil filler hole,all ok?would a pressure regulator help on fuel line,reduce pressure from 6psi to 4.5psi?