Im flumoxed

[unfazed]

Carb icing only happens in temperatures of around 4 degrees or less. It can happens from startup on the fazers until they reach operating temperature, but not after as the carb heaters prevent it. Some of the fazers came from the factory with a blockage in the coolant circuit in the carbs and are more prone to it, but is easily fixed.

Since the issue happens during a run of a few miles in excess of 70mph and drains the carbs it is most likely the pump that is misbehaving.

Bypassing the pump on a full tank of fuel is the easiest way to check a faulty pump if you do not have special pressure testers.