COOLING FIN STRUCTURE FOR VEHICLE-MOUNTED INTERNAL COMBUSTION ENGINE

摘要

An internal combustion engine (10) mounted on a two-wheeled vehicle has a forwardly tilted or substantially horizontal cylinder, and a cooling fin structure (31) including parallel cooling fins (30) extending in the direction of advance of the two-wheeled vehicle is formed on the upper surface of the engine. Reinforcing ridges (34) are formed integrally with the surfaces of the cooling fins (30), and the reinforcing ridges (34) of each cooling fin (30) are adapted not to be connected to the reinforcing ridges (34) of adjacent cooling fins (30) and to the adjacent cooling fins (30). The reinforcing ridges (34) are alternately arranged. Also, the reinforcing ridges (34) are arranged so as not to be superposed on the reinforcing ridges (34) of adjacent cooling fins (30) in a view in the longitudinal direction of the cooling fins. Bottom walls (35) between adjacent cooling fins (30) extend in the direction of advance of the two-wheeled vehicle. The construction makes earth and sand less likely to accumulate in the cooling fin structure, so that the cooling fin structure can be easily cleaned and cooling performance of the structure does not deteriorate.