14.5 Briggs starts but run rough and backfires through the carb.

[glassdiigger50]

Hi everyone I'm new to the forum and I hope someone can help me out. I have a 14.5 HP Briggs motor that runs rough and backfires through the carb. I adjusted the valves twice and checked the flywheel keyway and it was fine. I also checked the pushrods to make sure they were seated in the cups and were not bent. Things I have not done, check the plug or the coil but I think they are ok because it starts right up, but I do have to turn the key a couple of times to get it to turn over like it has to much compression. I have not cleaned the carb, checked for bent valves or carbon buildup or checked the head gasket. I hope someone can help me or give me some more ideas. Thanks.