Small Engines (Lawn Mowers, etc.): B&S 10A902 revs up and down, push mower, govenor

Question
As soon as I start my push mower, the engine revs up and down like the govenor is broken. I took off the air cleaner, and can see an arm coming from inside the engine pulling some springs back and forth as it speeds up and slows down. I am reasonably handy - what might be causing this and can I fix this or should I call a local shop?

Answer
Hi Bill,

The usual cause of carb "hunting", is a weak governer spring.  Although it might look fine it may not be and I would replace it.  Another possible cause is a float problem.  If not enough fuel is present in the bowl, then the float cycles open and closed.

Let me know how you make out.
Michael