about 2 weeks ago my cub which i use to mow around the place and a few acreages in town ,and pull a pickup bed trailer around the animal pens started smoking, to me its black smoke indicating unburnt fuel, maybe a little oil, not much , carb was new last year its the ih type, now today i did all the mantenence i can to a cub, thinking the air cleaner wool might be clogged, causing it to run rich i took it off and cleaned it completely it wasnt clogged, changed the engine oil, as well as the oil in the air cleaner cup, and oil filter,also disassembled and cleaned the carb, nothing in it either,and it seems to be working properly, no choke half on ect, cleaned the fuel sediment bowl, then decided since i had the hood off anyway, id run a compression check, not good, if my gauge [ kd brand] can be believed, 90, 25, 50, and 90, front back , adding a small amount of oil to the number 2 cylinder only brought it up about 5 lbs, rings should have brought it up more right? now at 25 lbs the cylinder should not even fire, neither should the number 3, assuming it takes 90 psi to make a normal engine run, but the cub doesnt miss, and at full throttle if it had bad rings it should smoke like a truck on acold morning, but adding rpm actually takes the smoke away its barely noticable, and i still claim its black smoke, the carb setting is for highest idle speed, which is about 2 turns out from the stop, so what next? would valves not seating due to carbon cause the low readings? but there is no popping thru the stack or intake, and the crankcase breather where the oil dipstick is has some blowby but no more than it always had, i need ideas, here this is a daily use tractor, and im in nm, which means there is no getting a rebuilt cub engine around here, i dont have the measuring tools to accurately do a engine overhaul here, and there is no machine shop for 200 miles. and by the time i pay for that i could just buy another tractor , if i could find another tractor id consider it or upgrade to an a, super a, or even a b,provided it came with a good belly mower, but none west of ia that i can find,