Primer bulb. The primer bulb draws fuel into the carburetor to make the engine easier to start.
Zama carburetor. If the carburetor is clogged, the engine won't get enough fuel. As a result, the engine may not start or may run rough. The carburetor can often be cleaned or rebuilt, but may sometimes need to be replaced.
Base assy. primer
Needle, high speed
Needle, low speed