Small engine primer bulb. The primer bulb draws additional fuel into the carburetor to help start the engine.
Champion Spark Plug (RCJ7Y). The spark plug ignites the fuel and air mixture in the engine's cylinder to power the engine. If the spark plug is has fouled (if the tip of the spark plug is burnt or damaged), the engine may not start or may run rough.
Small engine carburetor gasket and diaphragm kit. If the engine runs rough, then the carburetor may need to be cleaned, rebuilt, or replaced.