Scooterotica

The brass tube visible through the main carb body.

My question is can it be easily removed in order for the carb to be bored out.

Cheers

remove float bowl and needle atomiser can be unscrewed with flat bladed screwdriver.
PS the tube that u can see is the top of the atomiser.......

I understand your original question, the atomiser screws into a brass housing (diffuser) which protrudes into the venturi, I have successfully removed these in the past by filing (narrowing) the (unwanted) atomiser, reducing the diameter so that it will pass through the carb casting/rim in its original location.
screw the modified atomiser into the diffuser tube and knock it gently, you will see the diffuser drift away from the carb body.
have done this in changing 4t and reedvalve varients of the phbh over to the diffuser which the normal AV atomisers require.
hope this makes sense and helps

Yes the spray tube / diffuser is just a push fit.
If you converting a four stroke carb have a read of this
http://scooterotica.org/forum/viewtopic.php?f=7&t=10032
Russ

Cheers for that, so the atomiser diffuser is simply an inteference fit and can simply be drifted out and pressed (twatted ) back in.

yes