This is the RB30 carby mod I was talking about.
Start by removing the air filter from the top of the carby. Then undo the 4 carby base bolts (nuts actually), one of the nuts you will have to lift the carby up a bit to get it right off. The carby can then be moved to one side without having to disconnect anything else. Be careful when you lift the carby and try not to damage the base gaskets.
The bit you need to modify is the heating element in the spacer directly under the carby. Disconnect the wires going to the heating element and carefully remove the spacer. This is what it looks like when you first remove it.
Carefully drill out the pins surrounding the honeycomb element, and push out the element. The can looking thing on the other side just pushes out.
And what you're left with should look like this...
Installation is the reverse of removal.
Tony