Two-stroke engine for a portable handheld work apparatus

The invention is directed to a two-stroke engine for a portable handheld work apparatus such as a motor-driven chain saw. The engine includes a cylinder housing and a crankshaft journalled in shaft bearings. The cylinder housing is closed by a crankcase cover. Half shells are formed in the cylinder housing and the crankcase cover to accommodate the shaft bearings. Overflow channels are formed in the wall of the cylinder and lead from the crankcase to the combustion chamber. The overflow channels are open at their ends facing toward the crankcase cover and interrupt the support surface of the half shells formed in the cylinder housing. An adequate support of a small crankshaft bearing is ensured for an arrangement of several overflow channels. This is achieved in that the half shells are configured with a significantly larger diameter than the outer diameter of the shaft bearing and a support shell is seated in the free space between the half shell and the shaft bearing. The support shells close the gaps in the support surface of the half shells.