CS30 is an O/E bearing number and only supplied to manufacturers under that reference and not supplied through the bearing resellers. It is a special 2-stroke crankshaft bearing designed to operate in the limited lubrication situation of a 2-stroke engine. It has a special heat-treatment of the bearing cage and specific running clearance.
Honda Part #: 91008-KAE-731
Never use the general engineering bearing 63/28 C3 or C4. These get sold a lot on Ebay etc. and you probably get away with it in a crosser.