Bearings represent one of the main responsible of friction losses in internal combustion engines and their lubrication performance has a crucial influence on the operating condition of the engine. In particular, the conrod small-end bearing is one of the most critical engine parts from a tribological point of view since limited contact surfaces have to sustain high inertial and combustion forces. In this contribution an analisys is performed of the tribological behaviour of the lubricated contact between the piston pin and the conrod small-end of a high performance motorbike engine. An algorithm is employed based on a complementarity formulation of the cavitation problem. A comparison between two different approaches to simulate the asperity contact problem is performed, the former based on the standard Greenwood-Tripp theory and the latter based on a complementarity formulation of the asperity contact problem. The influence of different physical and geometrical parameters is discussed in order to provide preliminary guidelines for the correct design of the coupling. In particular, the clearance between the conrod small-end and the piston pin, the surface roughness and the stiffness of the piston pin are considered as design variables. A model validation is performed by comparing the results with those obtained adopting the commercial software AVL Excite Power Unit.