Hi Steve,
It has to be the needles or the the float itself or the pin that the float pivots on. It will be dirt related, so either the needle has gum on it or its slot, or the float could be punctured or its pivot needle is gummed up stopping it from going up and down correctly.
As I say I had this issue myself and it took me nearly 100 miles of very varied riding with wide open throttle for the problem to cure itself. Always use fresh petrol. I found that Tescos 99 ron helped. You have to work the petrol tap, open for the bowl to fill up, then closed to empty the bowls, then open again etc etc…………….if that doesn’t work then all you can do im afraid is carbs off for a proper clean. Its a very common problem for all honda’s of the period.
Regards,
Nat.