I have posted a few times on this tractor and am scratching my head and confused. I was running good and through all your help determined it was “wet stacking”. Ran for awhile and it went away. Got it out the last cutting of hay to use and it ran great until I got home. It started to run rough almost like it had a pulling cam. Started to smoke and really blow out out the exhaust. I decided to do a compression test and had 300psi on cylinder 1 and less than 100 on 2 so I stopped there and decided to pull the head and see if I had a problem with the rings. I have it apart and have found nothing but cylinder 2 exhaust valve to be very oily. I’ve attached picture. Everything looks normal. Going to have a local machine shop go through the head and see if I have a bent or sticking valve or gas valve guides. Can a worn out guide cause a backfire sound ? I know it can cause the oil I’m seeing if it’s bad enough. I think the rings are ok since theee was no fuel in the oil.