Hi I am Rick
Ok my mower is a Craftsman 30" deck Model # 917.280330 sn# 030309A002530 Engine Briggs and Stratton Model # 31C707 Type # 0603B1 Code # 081205ZE
My self I am a certified aircraft mechanic, I restore old cars for a hobby, I started keeping my lawn mowers running when I was 10 years old and have been doing so ever sence I am 64 now. I also keep my motorcycle and boat running. Ok now about my mower what i mean about run rough at hi rpm is it fires right up runs very smooth from idle to about mid throttle from there to full throttle it runs rough rpm up and down and pops out the exhaust. I have checked the key on the flywheel to crank it is fine I adjusted the valves I did it cold and I set int. valve at .004 and exh. valve at .006 I removed the carb disassembled it I found nothing but I cleaned it out with carb cleaner and blew it out with compressed air. Put it back on fired it up and check for any leakes around carb and intake found nothing. I did a leak down test I did it on a cold engine got about a 20% drop. I put in a new spark plug and a new gas and airfielter. also gas is fresh.I was going to post a picture of my mower but i can not figure out how. thanks in advance for any help.