If you need to buy a Harley CV carburettor for whatever reason, make sure that the carb is complete with its enrichment device - this screws into the carb body -  as often you'll find the whole enrichment device has been robbed to fit a Mikuni HSR 42 oir similar.

Parts needed for the enrichment valve are:

27580-88 Cable Guide
27582-88 Cable sealing cap
27581-88 Cap
27315-88A Spring
27583-88 Starter valve

just under £20 from your favourite Harley dealer.