Small Engines (Lawn Mowers, etc.): Briggs & Straton Motor hard starting, briggs straton, air leaks

Question
I have a Briggs & Straton 3.5hp 148cc lawnmower motor. Model #92902 type 2133-01 code 82030201
It is very hard to fire. Seems like lots of compression. When you finally get it started it runs for about 5 minutes and then runs rough and stalls. Then it is very hard to restart.
Changed oil, new spark plug, new gas, clean air filter.
Am I looking at a new carb or something simpler?

thanks
brad

Answer
Two possibilities.  The first could be points but based on your code number you should have electronic ignition.  Briggs started putting electronic ingition on is 1981 but it is possible your engine had points.  You can tell by looking at the ignition coil located under the top sheet metal cover.  If you see any wires running under the flywheel then you have poins.

Most likely the problem is the carb.  The aluminum carb body tends to warp over time.  This causes air leaks between the tank and carb.  You can remove the tank and carb, dis-assemble including removing the fuel pipes and running a flat file across the carb bottom in several directions will tell you if it is warped.  High spots will be shiny where material is removed and low spots will be dull.  You can try to true the carb...sometimes works sometimes doesn't.
If you really want to keep the mower then you might consider upgrading the carb with a used or new one.  Try your local mower dealer to see if they have any used pulsa-prime carburetors.  
Let me know if this helps.
Eric