The fuel lines conveying fuel from the fuel to and from the engine compartment are made from a semi-flexible plastic material.
 Within the engine compartment, the original installation used soft rubber fuel hose to complete the connections to the fuel filter and carburetor. 
The original installation encased the engine compartment lines in a black plastic sheath.  The sheath is a good idea, it protects from the heat and potential chafing from moving parts.  Instead of a plastic sheath, I found some heat-reflective tubing from Summit Racing.  I don't know how much difference the reflective coating makes, but I must encase the fuel lines in something, so I might as well protect them from the heat as well.
Up near the carburetor, I used new fuel supply hose to connect the new fuel filter. I heard a story of one CX that burned because the hoses loosened from the carb connection, so I used two hose clamps at the carb for supply and return.