Accepted Answer

The carburetor. If the machine has a choke, close it slightly and it should smooth out. That will verify the problem is a lean fuel mixture. You can clean the carburetor and sometimes it will correct the problem, however, honda carbs are a little finicky. If cleaning it doesn't work, they are surprisingly not too expensive, around $35 usually.

When you close the choke and the engine runs better, the fuel air mixture is lean due to the carburetor not letting enough fuel through the passages. Assuming you have full fuel flow to the carb, the carburetor is likely to blame, remove the bowl and spray carburetor cleaner up the main nozzle into the intake, and any other holes you see. It is also helpful to run a strand of copper wire through any hole you find. If this doesn't fix the problem, you may need to remove and soak the carburetor in a stronger carburetor cleaner, reassemble and test. Provided you have good flow to the carb, if it doesn't repair the problem, replace the carburetor.
If you do replace the carburetor, make sure you pay close attention to the gaskets and spacers, honda sandwich's the carb between all kinds of stuff, and it makes reassembly a three armed job.
Let me know how you make out!

Expert:	Chris Huber
Pos. Feedback:	100.0 %
Accepts:
Answered:	7/24/2009

Small Engine Technician

20 years experience. Briggs and Stratton Master Service Technician. Dealer for most engine lines.