Troy-Bilt Bronco rebuild

All right I'm rebuilding an old mower that didn't run I reran the lines cleaned out the gas tank put a new carburetor on it and it started up but it stinks really bad could it just be maybe some spilled grease on the exhaust or clean out the cobwebs or I mean but it's stunk bad and it's kind of just smoking pretty good so I don't think it's just cobwebs ideas? It's a Kohler motor color courage I do know I'm going to have to take off the valve cover and put a new seal on it because it is leaking oil pretty bad I had to do that on a old Cub Cadet I had to other than that I really can't figure out what the smoking or smell is it's can't really identify it be honest with you and good smell like grease burning but why would it smoke that bad?

I changed the oil and filter before I even attempted to start it just for simple fact I had no idea how long it had been sitting there. Oil in the exhaust could very well be the culprit. It definitely was not a burning belt but I'll do as you say just to make sure. Gotta change all the belts anyways. Also the cover has been off thruout the process. I happen to be a little O.C.D. so the first thing I did was clean it up. Knock the cobb webs out and so on. I'll throw anything you got at it. And I already added seafoam to the crankcase. And fuel.