A portable working
machine comprising a tool unit (1) with a disc guard and a circular tool (3), and a
machine unit (2) with a
filter system (10), an
internal combustion engine (11) with an engine cylinder (13) with bore (12) having a centre line (30), a
crankshaft (14) and a
crankcase (15), a
fuel tank (17), a
muffler (18) with an entrance port (46) provided in the rear side of the
muffler and facing an exhaust port (47) of the cylinder, handles (19, 20) controls (21, 22) and supports (23, 24) on the underside of the
machine unit for allowing upright positioning of the machine on a flat ground. The cylinder bore (12) is inclined forwards in a direction towards the tool unit, such that the centre line (30) of the cylinder bore forms a tilt angle larger than zero, in the direction, to a perpendicular to any or both of the following lines: (a) a
base line (33) which is a line coinciding with a horizontal surface on which the machine is resting in an upright position, when the supports on the underside of the machine unit contact the surface, and (b) a tangential line (33′) extending from a
peripheral point of the tool, on the lower part of the tool when the machine has an upright position, to the bottom side of a rear support of the machine unit.