Hi guys , not in business just mow at home . I have 2 acres of grass and I have a craftsman 17hp OHV Briggs & Stratton mower . M#311707 . Second year I've owned it (Its 90s model ), and I changed the oil before the first cut this yr . It died on the second cut this year (wifes been push mowing , phew) .Anyway , it ran , then when I engaged the mower deck or put it under and type of load it ran real ruff and blew a THICK white smoke...like thick enough the fire dept might get worried , no lie . It would then stall . I did a compression check at it reads 80 . I'm no mechanic , don't know where to go from here . I am mechanically inclined though and do my own vechicle worked..swaped engines ect , so I should be able to handle this . I was planning on maybe getting a rebuild kit , guessing piston rings , and the thick white is oil burning ? Figured I better ask people who know what thier doing before I do anything major . I did peek under the valve cover , and took the rockers off to spin the valves thinking maybe a piece of junk goit under one , weather I have them on correctly or not now is unsure . I doubt it because I cant keep it running now . Any help would be great .