If your carburetor is already plugged up you will have to clean it first to be effective. Seafoam will help keep your carburetor clean and also act as a fuel stabilizer. Yes it's effective at removing varnish but like I said if the passage is plugged it can't flow through to do it's job. The passages in the carburetor are extremely small and easy to plug with contaminated fuel. Very important to use clean fuel.
I purchase premium gas with no ethanol and add 1 ounce of Seafoam per gallon as a stabilizer and fill my scooters from that gas container.
Chevron Techron is a excellent cleaner as well. Another thing they do is help remove carbon deposits on the top end of the engine.
