Re: Carb Trumpets
I understand that even short carb trumpets can improve torque in the mid ranges, 1/2 inch ones fitted inside the Filter housing. There are various styles available from Moss.
You should double check that you have the gaskets between the carbs and Air Filter the right way round too as if fitted upside down, and they will fit, the two breather holes above the mounting holes get closed off and this will cause the problem you describe. Hope this helps..