Small Engines (Lawn Mowers, etc.): Surging Engine, honda gcv160, valve clearance

Question
Have a Honda GCV160 5.5hp on a piece of RR equipment. The engine surges regardless of throttle setting. The only way to keep it operational is to run with almost full choke and the engine does run better under load. I replaced the old carb with a new one, flushed out the fule line and tank, but the engine still surges. Could the problem be the gasket, spacer or a minute hole in fuel line. This is pushing me past my normal level of insanity. Thanks for any help.

Answer
I would check the gasket(s).  Make sure the gasket holes are not too small or too larges.  I have incorrect gaskets on several engines...this can drive you crazy!!!

Make sure the spacer is not warped.  A little Permatex 2 non-harding will usually seal any minor warping.

Have you checked the valve clearance?  Is the intake valve sticking?  Does it run the same way with the air filter removed?

Eric