Integrated cam drive and oil pump assembly for motorcycle engines and the like

An integrated cam drive and oil pump assembly for motorcycle engines includes an oil pump body, which is connected with the engine crankcase, and has an oil passageway with a pump outlet portion communicating with an oil reservoir. A pinion gear is positioned in the interior of the oil pump body, is connected with the engine drive shaft for rotation therewith, and mates with an idler gear. A first cam drive gear is mounted on a first camshaft, and mates with the idler gear. A second cam drive gear is mounted on the first camshaft in an axially spaced relationship with the first cam drive gear. A third cam drive gear is mounted on a second camshaft, and mates with the second cam drive gear. A cam chest return gear has a first portion extending into the cam chest sump to draw oil therefrom, and a second portion mating with the idler gear adjacent the pump outlet portion of the oil passageway, such that oil drawn from the cam chest sump by the cam chest return gear flows from the cam chest sump, through the oil passageway, and into the oil reservoir.