A two-cycle engine heaving a pair of disk wheel shaped counterweights attached to the crankshaft. The rims of the first and second counterweights provided with a plurality of parallel grooves arranged continuously around the circumference of the rims and extending from an outer edge to an inner edge of the rims. The grooves are angularly disposed with respect to an axis of rotation of the crankshaft and in a direction against the direction of rotation of the crankshaft. The grooves of the first counterweight are aligned with the grooves of the second counterweight whereby the corresponding grooves form a “V” configuration.