Small Engines (Lawn Mowers, etc.): cylinder not firing, engine model type, head gasket leak

Question
QUESTION: I have a 2 cylinder 21hp Briggs and Stratton vertical shaft OHV engine that carbons the one plug up as soon as you start the engine. The other cylinder works just fine. I have good spark and good compression. I also checked the valve clearance. What could be causing my problem?

ANSWER: What is the engine model, type and code number?  What is the valve clearance on each cylinder?  Compression on each cylinder?

Is there an intake or head gasket leaking?

Do you have spark on both coils?

Send me the engine numbers so I can look up parts diagram.

Eric

---------- FOLLOW-UP ----------

QUESTION: The engine model is 40H777, Type is 0242 E1, Code no.is 040220YG. Doesn't seem to have an intake or head gasket leak.Yes there is good spark coming from both coils. Vale clearance on both cylinders is .003 and .005. Compression is 185 on one and 183 on the other


Answer
Rules out compression.  Have you tried NGK spark plugs?  Have you cleaned the carburetor?  May be a restriction in one of the carb barrels.

Does the plug carbon enough foul the spark plug?

Do you have an electronic choke module?  If so, when the engine warms up is the choke fully open?

Eric