B & S 17.5 hp ohv carb trouble?

I have a murray riding mower with a 17.5 hp ohv engine that wont start. Will run when I pour a little gas into carb. The bowl is getting gas, it just does not seem to be supplying the carb with gas. Any suggestions? I have cleaned bowl, and replaced spark plug. Will carb cleaner help and how is it applied? Fuel lines are in good condition. Someone suggested that I take a small wire and clean ports on carb. If so how and where are these located?

jkh
October 2006