Small Engines (Lawn Mowers, etc.): craftsman 10hp riding mower, compression test, exhaust valve

Question
the mower was dormant for a few years sears mod.# 502.255060 engine #143426072ser20500 about 12 years old.i disassembled and cleaned the carb.,new plug it runs fast and slow but constantly pops from the exhaust.carb adjustments do not stop the popping.plug gets sooty black. upon acceleration carb spits fuel with air filter off. any ideas will be appreciated.
daryl lucas
d340@optonline.net

Answer
Hi Daryl,

Fuel spitting from the carb indicates a leaky intake valve.  Exhaust popping could be an exhaust valve.
You could do a compression test to confirm this.  Then check the valves.  They may be lacking clearance, sticking or need reseating.

Let me know how you make out.
Michael