If you are thinking of boring out your Amal TT to a new choke diameter - i.e taking a 1 1/16" bore out to 1 5/32", then you will first need to remove the Choke Tube. We can supply this little but important item in case yours gets damaged or has already been damaged - as they should protrude slightly from the bottom of the choke body, up into the air flow.
Amal TT and RN racing carburettors have always been less common to find than normal road carbs, and the outer choke tube was normally stamped with the choke size (i.e. the diameter of the inlet tract), which should also correspond to the size quoted for your given model of engine. Amal 10TT/RN were originally supplied in a variety of bore sizes from 1 1/8" to 1 3/16" (and a few were made for the Works factory teams at 1 1/4" I gather, as well as specials for Vincent Black Lightnings and similar). Below that 15TT carbs were made with a smaller throttle slide, that allowed up to 1 1/16" choke. As can be expected - some sizes are more sought now than others - particulalarly the larger sizes, which were often fitted to 500cc Norton SOHC and DOHC engines. It is possible to bore out the body of a TT carb to these larger sizes, but often this requires also boring the central alloy choke that is bolted into the carb body (that the throttle slide fits over) - but to do this requires removing the small brass choke tube that is threaded into the alloy body - and are very easy to damage on removal (and often stuck fast).
I do not profess to be an expert on doing this - but I have done it a few times and I know the secret to removing an old one is to make a small tubular adaptor with a screw head, and a hole through it centre for a 2" x 1/4" bolt. You then put the bolt through the adaptor and the the old choke tube (which will be in situ in the old mixing chamber) and tighten it up. Put the mixing chamber in the oven until spit hot (to loosen off the old choke tube) then unscrew the adaptor and hopefully the old choke tube will budge. The small bolt ensures the screw head is kept tight against the choke tube. However, invariably this can get chewed, in which case having a new one is handy!
See photographs for my own adaptor for doing this.
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