Rollover engine problems

[shrek18]

Hey all,
Got a couple quick questions I want to bounce off the small engine gurus. I have a 2000 ish Deere M665 z track with the 25hp v twin kohler. Its been a great mower but a week ago I rolled it over on its top while mowing a ditch. While crawling out from under it the unit got shut off within 5 sec of the flip. I rolled it back over and let it sit. It started and burned some oil for a bit but it cleaned up after 5 min. I had to add 1/4 quart to get it back full of oil. Ever since the roll over I notice any time on the side hill of the ditch or going up a slope it bogs down hard and looses power. I has stalled twice now since the last mow. I did notice it has been loosing power even on the flat ground and just mowing grass thats 2 inches taller than the setting. I did see the air filter was coated in oil so i ordered a new one but Im at a loss. It still lacks power. I run 91 non ethenol BP gas thats fresh. It has had a recurring issue of when it idles it acts as if it is loading up, like the choke is on. It starts blowing black smoke and it takes a while for it to come out of it, maybe 10 sec. I noticed that got worse since the rollover. It has 750 hours and has been maintained by the manual. My next move was going to be take the carb off and clean it and replace the gaskets. Is there anything else you guys would do?
I appreciate any input.
Thanks,
Paul

 

[Rivets]

Removing and rebuilding the carb is the first thing I would suggest. If that doesn’t solve the problem the next thing I would look at is the valve clearances. Rolling the unit can do many weird things to an engine. Wouldn’t be the worst idea to do a complete tuneup at this time, plus check to see if oil got into the fuel pump. Might have ruptured the diaphragm.

 

[shrek18]

I

Removing and rebuilding the carb is the first thing I would suggest. If that doesn’t solve the problem the next thing I would look at is the valve clearances. Rolling the unit can do many weird things to an engine. Wouldn’t be the worst idea to do a complete tuneup at this time, plus check to see if oil got into the fuel pump. Might have ruptured the diaphragm.

I am fairly certain that my engine has hydraulic lifters. when it started to smoke and load up a couple years ago I went to adjust the valves and there was no way to adjust them. I will probably do the plugs as well. Thanks

 

[SHB]

You might check to see that both cylinders are firing. Had a Koehler v-twin that would just about die when engaging the blades, bog down in grass over 2”. Found problem by pulling plug wire, one had no effect, the other killed it. Problem was the stud the supported the rocker arm on the left cylinder had worked loose.