How can I remove spilled oil from my lawn mower motor ?

While removing the lawn mower blade for sharpening I tipped the mower to the wrong side and the oil must have spilled into the motor as it only runs at about half-power now and stalls and sputters constantly. Is there anyway to flush it out or will it eventually burn itself off the parts ? It must not have leaked into the carburetor as it doesn't smoke when running. There is no service centre near me and I must do all my own repairs.