Internal combustion engine with mass balance

An internal combustion engine provided with a mass balance means of the second order, the mass balance means includes two balancing shafts respectively arranged on each side of and parallel to a crankshaft of the engine, balancing weight means on each of the balancing shafts, means for directly driving one of the balancing shafts in a direction of rotation of the crankshaft and for indirectly driving the other of the balancing shafts in a direction of rotation opposite the direction of rotation of the crankshaft, characterized in that a lid means is provided for covering an opening of a crankcase of the engine, a bearing cover means is provided for covering a main bearing pin of the crankshaft, the directly driven balancing shaft is mounted on an inside of the lid means, the indirectly driven balancing shaft is supported on the bearing cover means, the driving means includes a sprocket wheel attached to a crank web of the crankshaft, a chain means cooperable with the sprocket wheel attached to the crank web of the crankshaft, a drive shaft means having a drive sprocket wheel on a first gear mounted thereon, a further gear cooperable with the first gear is provided on the indirectly driven balancing shaft, and in that the drive shaft means is supported in the bearing cover means and an adjacent bearing cover for the crankshaft.