The invention discloses a crankshaft connecting rod assembly for motorcycles. The crankshaft connecting rod assembly comprises a flywheel. A rotating speed sensor pulse wheel is arranged on the frontside of the flywheel. The flywheel is welded to the rotating speed sensor pulse wheel. A crankshaft is arranged on the front side of the rotating speed sensor pulse wheel. The crankshaft and the flywheel are connected through a key. A main shaft is arranged in the crankshaft. The main shaft is welded to the crankshaft. A main bearing upper bearing bush is arranged at an upper end of the main shaft. A main bearing lower bearing bush is arranged at a lower end of the main shaft. The main shaft is rotationally connected with the main bearing upper bearing bush and the main bearing lower bearing bush. Thrust plates are arranged on the front side and the rear side of the main bearing lower bearing bush. The main shaft is rotationally connected with the thrust plates. A connecting rod is arranged at an upper end of the crankshaft. The crankshaft connecting rod assembly for the motorcycles has the beneficial effect that an oil ring is arranged to prevent oil from being splashed around; a first gas ring and a second gas ring prevent gas from leaking out during work of the crankshaft connecting rod, and prevent low efficiency; the whole structure is simple and firm, and mounting and dismounting are convenient.