Abstract: A four-stroke internal combustion engine is provided that is capable of use in many power tools, including those power tools subjected to tippable applications. The engine includes an oil reservoir and a crank chamber separated by a divider. The divider includes a slot that allows lubricant to move from the oil reservoir into the crank chamber and from the crank chamber into the oil reservoir in response to pressure fluctuations of the engine. The engine can include an insert positioned within the slot to at least partially restrict the slot thereby modifying the lubricant communication between the crank chamber and the oil reservoir through the slot. The insert can be wedge-shaped and at least partially define a passage such that when the insert is positioned within the slot the transfer of lubricant between the crank chamber and the oil reservoir occurs through the passage.