RobH wrote:You could cross-check the float heights between the good and bad carbs
Have you tried swapping the floats from your friends carbs.
Both floats 16013kv3950 and float valves 16011km9711 are still available

Hi Rob - thanks for your reply. I have cross checked float heights, but I did not try his floats in my carbs. I am however using the floats that came in the carb assembly I just got from Japan that are exhibiting the same problems. I guess it's possible that both sets of floats were bad - though seems unlikely.