I have a 1971 Triumph Tiger (single carb.). Is there supposed to be any kind of heat insulator on the carburetor or the intake manifold? The bike is hard to start after sitting for 5 minutes or so. After that it starts fine. Seems to be boiling the fuel out of the carb. when sitting. Would installing a phenolic spacer .100 thick help it? Thanks.

I always add a insulating gasket either between the head and
manifold or between the manifold and carb.  If there is room I
add both.  I use 1/8 inch thick fiber gaskets.

John