That's one reason you see the engine builder decals covering the outside of the starter.
Keep in mind that you are limiting the air entering the fan (fins on the flywheel) so not only the wind resistance is affected, but also the cooling ability. Fold the edges of the tape back so you can easily remove small pieces if need be on a caution or last minute on the grid before the feature. More heat can help seal up the cylinder and rings, help with more complete combustion, other small advantages, but it can also cause serious damage to your engine (ie ex guide, head gasket, cylinder head warpage, etc.)
Is the benefit worth the potential cost?
That's a question best answered between you and your engine builder.
Biggest advantage is the drag on the fins of the flywheel. If jetted correctly and kart isn't locked down, heat is easy to control. This is mostly utilized in the plate classes as they need every ounce of HP they can get.