Small Engines (Lawn Mowers, etc.): 3.5 B & S Generator surging, engine model type, govenor

Question
I have a Coleman Sport 1850 with a B&S engine. The engine runs great, starts on the first pull but surges constantly. Is this the govenor? No adjustments on this engine except the idle stop.

Also, how do you set the govenor?  

Answer
Most likely the problem is in the carb and not the governor.  What is the engine model, type and code number?

How long has this problem been happening?
Has the unit sat for a while?
When was the last time the generator ran correct?
How often and how long do you use the generator?

Let me know.
Eric