It´s only a two stroke. It has 2 spark plugs , the airflow intake adjuster is on the carburetor on the battery side(small screw with coil spring). Throttle adjusts on handlebars by the brake. If it misses and sputters with new spark plugs you might have a plugged carb. It is a single carb. with a single needle. Make sure to put additives in the gas. New gas every 60 days or it will gunk up the carb. IF you take the carb. apart , as long as you keep track of how you took it apart, is really simple to put back together. It has a single needle valve. Clean it out make sure no chucks are in the holes. And put it back together. Since it is a single carb. you don´t have to reset them. I´ve found it to be one of the most common problem with the bike(most bikes).