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?

Pull the main cover off and make sure there's no nests now in there...  
 
I gather what your smelling is not burning V-belts or idler pulleys?
You may want to remove every belt from the engine and run the engine just to confirm that.
 
An oil change wouldn't hurt.    Oil that may have leaked out over time and into the muffler
would take time to burn off.  
 
Do the above and let it run.  Some Seafoam in the oil and gas wouldn't hurt..
 
A customers machine:

 
 
 

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.

Sounds like you got a good plan..
 
The more I thought about it, I thought a frozen spindle, idle pulley (some are plastic), etc
would be your issue. With the belts off, spin and "feel" all of those as they do tend to wear and bind up.  Most folks don't check until too late.  
 
Plz post back on your progress.
 
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I'll definitely post updates about it for sure. I am in the middle of a little family emergency so I'm having to pause on it for a couple but whenever I take the next step I will let you know how it goes. Thanks for the advice

Weeks*