I bought a used Honda 217, 19cc and it pulsed in idle. I read all that I could on the internet. Cleaned the carburetor, new plug and air filter, bought a tac at Northern Tool, went from the small in line fuel filter to a regular filter, adjusted the idle arm to 3400rpm, and still had no joy. I then ordered a new carburetor on e-bay and installed it. The Carburetor fixed the problem. The old carb might be fixable if I took it apart, but just cleaning the small holes and such did not do the trick...the new carb did. It now starts on first pull, idles smooth and steps up to the blade spin without much hesitation. Cuts great with the dual blades.