My experience with motors in general popping through the carb is generally a timing issue. But not sure about this on my mower. Its a 20hp B&S V-twin. Basically, I was cutting "the field" last week. After the field kicked my ass all week (broken belt, fresh air intake broke, wheel fell off, flat tire) I finally got back up there it fix it (flat tire) The mower sat in the field all week (10days) with no front tires and on an incline. Not steep enough for the tractor to roll on its own. Machine ran perfect until I got the tires on and fired it up. First, I rolled it down the hill and let it sit for close to an hour. Just incase the oil was somewhere it should not have been. When I went to start and run it, it instantly ran like ****. Spitting and sputtering and popping through the carb. With the mower engaged, it ran smoother, but still popped through the carb. What is the first thing I should look at and then anything else. As in a next step thing. Thanks for any input.