Today I checked the supply. With pump on, fuel arrives into the engine bay no problem. If I connect the brass splitter and the 2 pipes going to the carbs, fuel prioritises one side and doesn't supply the other, but if you block the end of the flowing pipe, it swaps over and then both run fine. Then I refitted the carbs after emptying the float bowls and turned pump on again. After pumping the throttle a few times and running the pump for about 30 secs, I removed the tops off the carbs and the right one was full and the left empty! So would this basically mean after using whatever fuel gets into the left carb, that one stops and I'm basically running on 2 cylinders.....hence no power?

How can I get it to feed both sides all the time?