Most small 4-stroke gasoline engines use what is called splash lubrication.
On horizontal-crankshaft engines, a dipper on the bottom of the connecting rod scoops up oil from the crankcase for the bearings. In this engine it is also able to splash oil up to the valve mechanism. Alternatively, an oil slinger can be driven by the camshaft.
A similar system is used in most small vertical-crankshaft engines. Oil is also splashed up to the valve mechanism.
