When I got this tractor I was told it needed injectors. Supposed to have new rings and pistons. Ran but really allot of black smoke sometimes white mixed in and reduced power. I put in some new injectors. They were Kubota injectors. Looked and fit the same. The part number was even the same except the last digit Kubota 15271-5302-0 Kioti 15271-5302-1. They look the same, measure the same, fit and run but I have the same issue same with running very rich. The new ones even run richer than the old ones. Looking for a next step to try? Anybody got any suggestions what to try next. Any way to lean it out? Working on cars and trucks all my life. Not much experience with diesel and next to nothing on tractors.