Berkebile 2+2 Instant Gum Cutter case keeps well-maintained engines working better and lasting longer. This product reduces harmful emissions and can increase fuel economy which puts more money in your pocket and less in fuel and costly repairs. It also has the following benefits: 
Cleans automatic chokes, carburetors, choke linkages, and PCV valves & hoses 
Removes varnish, gum, & other deposits instantly 
Oxygen sensor safe 
Extension tube supplied for pinpoint application 
Application 
Carburetors & Chokes: Always start cleaning with engine cold and ignition off. Remove air cleaner. Spray and flush exterior surface of carburetor, allow to dry. After area is dry, start engine and spray short bursts into carburetor throat, flushing automatic choke and throttle (butterfly) plates. Stop spraying and restart engine if it stalls. Increase engine speed slightly until all liquid is drawn off. 
PCV Valves: Always start cleaning with engine cold and ignition off. Disconnect crankcase side of PCV valve. Insert extension tube into valve unit, spray a small amount of product inside, and shake unit several times to make sure check valve is loose. Flush immediately with water to avoid harm if on auto finishes, paints, or plastics.