I have a 16hp BS V and can't get it to idle up. Its been sitting a while and initially it started up and ran but smoked a lot. The oil seemed to be thin and possibly adulterated so I changed it and changed the spark plugs. Now it starts fine but won't really get to full throttle. No smoke now. What is interesting is one muffler is hot, and the other is not. Can anyone tell me what is going on?

Check and see if you have fire on both cylinders , if so check compression on both sides and compare.
Luck