Originally Posted by dan_vector

I think the Novarossi carbs have remained fairly constant in the last few years. The main changes are usually to the spray bar length and bottom needle length. The carb throat is the same for the flash as the latest engines.

Have you changed the orings in the Carb on the flash? The carb could be drawing in air when it gets hot. You can also look at bearings in the engine that can cause havoc with engine consistency.