A crankshaft and piston arrangement (10) for a combustion engine, comprising a piston (12) pivotally connected to a crankshaft (18) by a connecting rod (14), and balance means (24) comprising a connecting rod (26) and a balance arm (32, a, b, c) pivotally connected thereto, the balance arm being connectable at an end remote from the connecting rod to the engine and wherein the balance arm provides a balance mass thereby to balance vibrational forces created by the movement of the piston (14).