Small Engines (Lawn Mowers, etc.): garden tractor engine hunting, flat blade, speed jet

Question
Eric:
I have a Craftsman garden tractor with a 19.5 hp twin cylinder BS engine that is about 6 years old. I bought the unit brand new and to date nobody is played with the governor or other key components. Recently the engine has started "hunting" with rpms changing constantly. Before I spend any money on repair parts, can you please tell me the most likely causes for "hunting" and what remedies your recommend. Thank you  Bob

Answer
The most common cause of this problem is a dirty carburetor.  If you have an L head twin cylinder you can try draining the carburetor and cleaning the high speed just.  You will need complete access to the engine if you wish to try to perform this without removing the carburetor.  You may  have to remove the hood to access the high speed jet nut on the carburetor.

If you look at the carburetor you should see a nut on the lower portion of the carburetor bowl.  Removeing the nut will drain the gas out of the carb and allow access to the high speed jet.  You can remove the jet with a flat blade screwdriver.  Blow compressed air, from an air compressor, through the jet.  Re-install jet and nut.   Test the engine operation.

The other option, and is the preferred method, is to remove, dis-assemble and clean the carb in conjunction with flusing the entire fuel system.  Usually takes less than an hour with all the necessary tools.

Let me know what you decide to do.
Eric