Small Internal Combustion Engine and Garden Tool with the Same

A small internal combustion engine includes a housing and an internal combustion engine body arranged in the housing. The internal combustion engine body includes a cylinder， a crankcase， a piston arranged in the cylinder， a crankshaft arranged in the crankcase and driving the piston， and an oil pan arranged at a bottom of the crankcase. The oil pan has an oil pan inlet， and the housing has a housing oil inlet. A hose connected to the oil pan inlet and the housing oil inlet forms a fluid passage for lubricating oil to flow from the housing oil inlet to the oil pan. A related garden tool includes a power source assembly that drives a working assembly to operate via a power transmission assembly.