A power cutter comprising: a housing; a two stroke internal combustion engine mounted within the housing; a throttle switch by which the engine can be accelerated when the engine is running; means for providing aerated petrol for the engine; an air intake for providing air for the petrol supply means; a petrol tank for providing petrol to the petrol supply means; an exhaust through which the exhaust gases generated by the operation of the engine are expelled from the engine; an engine controller which controls the operation of the engine; an oil tank is for providing lubricating oil for the engine; an oil pump (130, 700) to pump lubricating oil from the oil tank to mix it with petrol, a sensing system which determines whether sufficient lubricating oil is being provided for mixing with the petrol in accordance with predetermined parameters, wherein the sensing system provides an indication to the engine controller of when the lubricating oil is not being provided in accordance with the predetermined parameters, the engine controller placing the engine either in an idle mode or switching it off when the sensing system indicates that the lubricating oil is not being provided in accordance with the predetermined parameters' characterised in that: the power cutter further comprises a support arm mounted on the housing and which projects forward of the housing; a blade mounting mechanism (70, 90, 86, 92) rotatably mounted on the end of the support arm and which is capable of being rotationally driven by the engine when the engine is running; and an air filtration mechanism to filter the air drawn in from the air intake for the petrol supply means; and in that; a blade mounting mechanism (70, 90, 86, 92) rotatably mounted on the end of the support arm and which is capable of being rotationally driven by the engine when the engine is running; and in that; and said sensing system determines whether sufficient lubricating oil is being provided in to the passageway for mixing with the aerated petrol in accordance with the predetermined parameters. a housing; a two stroke internal combustion engine mounted within the housing; a throttle switch by which the engine can be accelerated when the engine is running; means for providing aerated petrol for the engine; an air intake for providing air for the petrol supply means; a petrol tank for providing petrol to the petrol supply means; an exhaust through which the exhaust gases generated by the operation of the engine are expelled from the engine; an engine controller which controls the operation of the engine; an oil tank is for providing lubricating oil for the engine; an oil pump (130, 700) to pump lubricating oil from the oil tank to mix it with petrol, a sensing system which determines whether sufficient lubricating oil is being provided for mixing with the petrol in accordance with predetermined parameters, wherein the sensing system provides an indication to the engine controller of when the lubricating oil is not being provided in accordance with the predetermined parameters, the engine controller placing the engine either in an idle mode or switching it off when the sensing system indicates that the lubricating oil is not being provided in accordance with the predetermined parameters' characterised in that: the power cutter further comprises a support arm mounted on the housing and which projects forward of the housing; a blade mounting mechanism (70, 90, 86, 92) rotatably mounted on the end of the support arm and which is capable of being rotationally driven by the engine when the engine is running; and an air filtration mechanism to filter the air drawn in from the air intake for the petrol supply means; and in that; a blade mounting mechanism (70, 90, 86, 92) rotatably mounted on the end of the support arm and which is capable of being rotationally driven by the engine when the engine is running; and in that; and said sensing system determines whether sufficient lubricating oil is being provided in to the passageway for mixing with the aerated petrol in accordance with the predetermined parameters. the power cutter further comprises a support arm mounted on the housing and which projects forward of the housing; a blade mounting mechanism (70, 90, 86, 92) rotatably mounted on the end of the support arm and which is capable of being rotationally driven by the engine when the engine is running; and an air filtration mechanism to filter the air drawn in from the air intake for the petrol supply means; and in that; a blade mounting mechanism (70, 90, 86, 92) rotatably mounted on the end of the support arm and which is capable of being rotationally driven by the engine when the engine is running; and in that; and said sensing system determines whether sufficient lubricating oil is being provided in to the passageway for mixing with the aerated petrol in accordance with the predetermined parameters.