Go down to a Harbor freight store or the like in your area and buy a small arbor press. I would not take the chance and beat a precision bearing out or in with a hammer. You run the risk of damaging the cage or the races. They need to come out square and go in square to the case. When I build or rebuild an engine I use a light oil to pre-lube the bearings so that they don't run dry during the initial running of the engine. I also use the same oil to lube the cylinder walls. Good luck!