I DRAINED THE TANK - CHANGED THE OIL BECAUSE IT HAD GAS IN IT -- IT IS BACKFIRING THROUGH THE EXHAUST -- I CLEANED THE CARB BOWL ETC COULD THIS THING BE OUT OF TIME I WAS NOT CUTTING GRASS JUST HAULING TWIGS IN THE CART IT STARTED SMOKING BLUE SMOKE AND THEN JUST CAME TO A STOP ANY SUGGESTIONS ON THE TIMING I NEVER HAD THE MOTOR APART THIS TRACTOR HAS LOW HOURS ON IT