Or electrickery - that's normal with the Rotax air cooled 2-strokes, just need a bigger one. Had this on a 40hp single carb engine on a microlight, the RPM needle just about flickered down from 3,000 at idle when you turned carb heat on - or in other words the power loss was trivial.
(It's the bit between the carb body and the air filter - about $300 a pair from Aircraft Spruce I believe).
Needless to say, I never saw any icing with this.
G