Is the heat riser working? The evaporation of the fuel as it passes into the intake manifold has a pronounced cooling effect- - - -that's why gas-engine airplanes use "carburetor heat" on takeoff and landing to assure there's no stall due to carburetor icing at critical moments in the flight. The heat riser is supposed to route exhaust gas under the carb base to minimize the tendency to ice, but unless the ice also forms on the inside of the carb, it won't seriously affect performance.
Jerry

"It is better to be silent and be thought a fool than to speak and eliminate all doubt!" - Abraham Lincoln
Cringe and wail in fear, Eloi- - - - -we Morlocks are on the hunt!
There is nothing noble in being superior to your fellow man; true nobility is being superior to your former self. - Ernest Hemingway
Love your enemies and drive 'em nuts!