Replace John Deere L120 Engine?
I'm having serious smoke problems coming out of the exhaust on my JD L120 riding mower. Constant white smoke that gets worse under load with much knocking and pinging, black smoke at severe loads. I'm considering working on the engine myself as a learning project as I have all the manuals which very clearly explain how to tear the engine down, check the boring, rebore if necessary, replace the rings, etc. It would be a hobby project to get myself some mechanical skills as I had fun rebuilding the carb (although the black smoke indicates I probably need to do some adjustment).
Trouble is, I need the mower this season and am willing to purchase a new engine for it but I'm having a hard time figuring out which engines I can use as replacements. I found a great deal on a 25hp Intek that looks exactly like my 20hp Intek and there are numerous new engines on eBay.
How can I determine with certainty if a particular engine will drop into my L120 chasis? I believe my engine is a 407777 0131YC (from memory so may not be exact), but how can I use the Model and Type information to look for replacement engines that will fit?